case study population biology

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Case Study: Loggerhead Turtles and Population Models

This case study focuses on survivorship curves and population models by examining a case about loggerhead turtles. The case starts off with a story about how beach visitors must follow certain rules to not disturb native turtles and nesting behavior.

Students watch a video that shows how biologists moved sea turtle nests after the BP Oil spill in 2010. From there, students learn about reproductive strategies (R -strategists and K-strategists), logistic growth curves, limiting factors and carrying capacity.

This study can be substituted for a traditional lecture on the topics, though instructors will need to pause and discuss certain concepts throughout the case.

Sea Turtle Reproductive Strategy

Type III survivorship curves are characterized by high mortality rates early in life, followed by increased survival as individuals reach maturity. This pattern precisely describes the survival trend of sea turtle hatchlings:

High Mortality in Early Life: Sea turtle hatchlings face numerous challenges as they emerge from their nests and venture into the ocean. Predators, both on land and in the water, pose significant threats. Birds, crabs, fish, and various other predators prey on these vulnerable hatchlings, resulting in high mortality rates during the early stages of their lives.
Increased Survival as they Grow: The survivors that manage to overcome these initial threats and reach a larger size exhibit a notably higher chance of survival. As they grow and develop, their survival rates increase, and they become more resilient to certain predators and environmental challenges.
Stable Survival in Adulthood: Once sea turtles reach adulthood, their survivorship tends to stabilize, and their mortality rate becomes more consistent.

Grade Level: 10-12 | Time Required: 1.5 – 2 hours

HS-LS2-1 Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.

HS-LS2-2 Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

HS-LS2-7 Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.*

Other Ecology Case Studies

The Wolves of Isle Royale

Are Invading Bullfrogs Harmful

Investigating Sea Turtles and Sex Determination

Shannan Muskopf

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Population Ecology

Over twenty-five percent of all amphibians are in serious danger of going extinct. Why are some species more vulnerable to extinction than others? How can current rates of individual survival and reproduction be projected into the future? The Earth’s human population has doubled in less than fifty years, and will reach seven billion in 2011. What challenges do we face with this unprecedented growth? What factors might most effect the rates of this growth into the future? Population ecology is the study of these and other questions about what factors affect population and how and why a population changes over time. Population ecology has its deepest historic roots, and its richest development, in the study of population growth, regulation, and dynamics, or demography. Human population growth serves as an important model for population ecologists, and is one of the most important environmental issues of the twenty-first century. But all populations, from disease organisms to wild-harvested fish stocks and forest trees to the species in a successional series to laboratory fruit files and paramecia, have been the subject of basic and applied population biology. An organism’s life history is a record of major events relating to its growth, development, reproduction, and survival. Life histories vary tremendously from one species to the next. Why all the variation? For example, why do some organisms die immediately after reproducing (some salmon and bamboos, many insects, and all grain crops), while others live on to reproduce repeatedly (most plants and vertebrates)? The study of population ecology includes understanding, explaining, and predicting species distributions. Why do species inhabit particular areas, and how are they prevented from establishing beyond their range limits? Such range questions have become popular in the last decade or so in response to concerns about climate change. To develop a rich understanding of population ecology, begin with this introductory overview, and then explore the other summaries you’ll find below.

Aging and Its Demographic Measurement

Allee Effects

An Introduction to Population Growth

Climate Change and Avian Population Ecology in Europe

Density and Dispersion

Game Theory, Evolutionary Stable Strategies and the Evolution of Biological Interactions

Introduction to Population Demographics

Population Dynamics of Mutualism

Population Ecology at Work: Managing Game Populations

Population Ecology Introduction

Population Limiting Factors

The Breeder's Equation

How Populations Grow: The Exponential and Logistic Equations

Environmental Constraints to the Geographic Expansion of Plant and Animal Species

Case Study: The Glorious, Golden, and Gigantic Quaking Aspen

Survivorship Curves

The Population Dynamics of Vector-borne Diseases

Global Atmospheric Change and Animal Populations

Semelparity and Iteroparity

Causes and Consequences of Dispersal in Plants and Animals

Disease Ecology

Ignoring Population Structure Can Lead to Erroneous Predictions of Future Population Size

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Enrich your students’ educational experience with case-based teaching

The NCCSTS Case Collection, created and curated by the National Center for Case Study Teaching in Science, on behalf of the University at Buffalo, contains over a thousand peer-reviewed case studies on a variety of topics in all areas of science.

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Lionfish Invasion: Density-Dependent Population Dynamics

Populations
Models & Simulations
Graph Interpretation

Resource Type

Click & Learn

Description

In this Click & Learn, students explore mathematical models that describe how populations change over time and apply these models to the invasive lionfish population in the Bahamas. They also use data from other species to learn how density-dependent factors limit population size.

The Click & Learn includes realistic and actual data from lionfish and other case studies. It provides opportunities to use the logistic growth model, graph data, and interpret figures from published scientific research.

The accompanying worksheet and “Case Studies Handouts” document guide students’ exploration. Some of the questions in these documents are identical to those embedded in the Click & Learn.

The “Resource Google Folder” link directs to a Google Drive folder of resource documents in the Google Docs format. Not all downloadable documents for the resource may be available in this format. The Google Drive folder is set as “View Only”; to save a copy of a document in this folder to your Google Drive, open that document, then select File → “Make a copy.” These documents can be copied, modified, and distributed online following the Terms of Use listed in the “Details” section below, including crediting BioInteractive.

Student Learning Targets

Describe invasive species and their impacts on ecosystems.
Define carrying capacity and explain how it relates to density-dependent population growth.
Use discrete-time and continuous-time logistic equations to model population dynamics.
Interpret data and graphs to describe how the population growth rate varies with population density in a logistic model.
Compare realistic field data to projections from models.
Use data from case studies to explain how various negative density-dependent factors regulate population size.

Estimated Time

carrying capacity, growth rate, invasive species, logistic growth, marine biology, mathematical population model, oceanography, population estimate, population regulation

Primary Literature

Green, Stephanie J., John L. Akins, Aleksandra Maljković, and Isabelle M. Côté. “Invasive lionfish drive Atlantic coral reef fish declines.” PLoS ONE 7, 3 (2012): e32596. https://doi.org/10.1371/journal.pone.0032596.

Côté, I. M., and N. S. Smith. “The lionfish Pterois sp. invasion: Has the worst‐case scenario come to pass?” Journal of Fish Biology 92, 3 (2018): 660–689. https://doi.org/10.1111/jfb.13544.

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Version history, curriculum connections, ngss (2013).

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AP Biology (2019)

SYI-1.G, SYI-1.H, SYI-3.D; SP1, SP4, SP5

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Ap environmental science (2020).

Topic(s): 3.4, 3.5, 9.8 Learning Objectives & Practices: ERT-3.E, ERT-3.F, EIN-4.A, SP1, SP2, SP5, SP6

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Common core (2010).

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Class 12 Biology Case Study Based Questions PDF Download

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In the pursuit of academic excellence, Class 12 Biology students often encounter case studies that challenge their problem-solving abilities and critical thinking skills. These case studies serve as valuable learning tools, allowing students to apply their theoretical knowledge to real-life scenarios. In this article, we will delve into the significance of Class 12 Biology Case Study Based Questions and provide a downloadable PDF resource containing a collection of such questions. So, let’s explore how these case studies can enhance students’ understanding and performance in the subject.

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Case study-based questions simulate real-life situations, encouraging students to analyze, evaluate, and apply their knowledge to address specific problems. By engaging with these scenarios, students develop a deeper understanding of the subject matter, making their learning more meaningful and relevant.

Table of Contents

Case Study-Based Questions for Class 12 Biology

These Class 12th Case Study and Passage-Based Questions will help you to score 95% in Your Board Exams.

Class 12 Physics Case Study Questions
Class 12 Chemistry Case Study Questions
Class 12 Biology Case Study Questions
Class 12 Maths Case Study Questions

Books for Class 12 Biology

Strictly as per the new term-wise syllabus for Board Examinations to be held in the academic session 2024 for class 12 Multiple Choice Questions based on new typologies introduced by the board- Stand-Alone MCQs, MCQs based on Assertion-Reason Case-based MCQs. Include Questions from CBSE official Question Bank released in April 2024 Answer key with Explanations What are the updates in the book: Strictly as per the Term wise syllabus for Board Examinations to be held in the academic session 2024. Chapter-wise -Topic-wise Multiple choice questions based on the special scheme of assessment for Board Examination for Class 12th.

Case Study-Based Questions Benefit Class 12 Biology Students

Comprehensive learning.

By incorporating case studies into the curriculum, Class 12 Biology students gain a comprehensive understanding of complex biological concepts. These case studies encompass a wide range of topics, from ecology to genetics, and offer multifaceted learning experiences.

Application of Theoretical Knowledge

Theoretical knowledge becomes more valuable when students can apply it practically. Case study-based questions bridge the gap between theory and application, empowering students to connect classroom learning to real-world situations.

Engaging and Interactive Learning

Case studies have an inherent appeal, as they present intriguing problems that captivate students’ attention. This engagement enhances their motivation to learn, making the subject more enjoyable and meaningful.

Tips for Effective Utilization of Case Study-Based Questions

Collaborative learning.

Encourage students to discuss case studies in groups. Collaborative learning promotes teamwork, diverse perspectives, and a deeper understanding of the subject matter.

Teacher Guidance

Teachers play a crucial role in guiding students through the analysis of case studies. Providing insights, posing relevant questions, and facilitating discussions can significantly enhance the learning experience.

Regular Practice

Integrate case study-based questions into regular assessments. Regular practice helps students become more comfortable with this format and boosts their confidence in tackling complex problems.

Class 12 Biology Syllabus for 2024

Check the complete syllabus below along with the new exam scheme.


	Reproduction	16
	Genetics and Evolution	20
	Biology and Human Welfare	12
	Biotechnology and its Applications	12
	Ecology and Environment	10

Detailed Syllabus:

Unit-VI Reproduction

Chapter- 2: Sexual Reproduction in Flowering Plants

Flower structure; development of male and female gametophytes; pollination – types, agencies and examples; out breeding devices; pollen-pistil interaction; double fertilization; post-fertilization events – development of endosperm and embryo, development of seed and formation of fruit; special modes- apomixis, parthenocarpy, polyembryony; Significance of seed dispersal and fruit formation.

Chapter- 3: Human Reproduction

Male and female reproductive systems; microscopic anatomy of testis and ovary; gametogenesis-spermatogenesis and oogenesis; menstrual cycle; fertilisation, embryo development up to blastocyst formation, implantation; pregnancy and placenta formation (Elementary idea); parturition (elementary idea); lactation (elementary idea).

Chapter- 4: Reproductive Health

Need for reproductive health and prevention of Sexually Transmitted Diseases (STDs); birth control – need and methods, contraception and medical termination of pregnancy (MTP); amniocentesis; infertility and assisted reproductive technologies – IVF, ZIFT, GIFT (Elementary idea for general awareness).

Unit-VII Genetics and Evolution

Chapter-5: Principles of Inheritance and Variation

Heredity and variation: Mendelian inheritance; deviations from Mendelism – incomplete

dominance, co-dominance, multiple alleles and inheritance of blood groups, pleiotropy; elementary idea of polygenic inheritance; chromosome theory of inheritance; chromosomes and genes; Sex determination – in humans, birds and honey bees; linkage and crossing over; sex-linked inheritance – haemophilia, colour blindness; Mendelian disorders in humans – thalassemia; chromosomal disorders in humans; Down’s syndrome, Turner’s and Klinefelter’s syndromes.

Chapter-6: Molecular Basis of Inheritance

Search for genetic material and DNA as genetic material; Structure of DNA and RNA; DNA packaging; DNA replication; Central Dogma; transcription, genetic code, translation; gene expression and regulation – lac operon; Genome, Human and rice genome projects; DNA fingerprinting.

Chapter-7: Evolution

Origin of life; biological evolution and evidence for biological evolution (paleontology, comparative anatomy, embryology, and molecular evidence); Darwin’s contribution, modern synthetic theory of evolution; mechanism of evolution – variation (mutation and recombination) and natural selection with examples, types of natural selection; Gene flow and genetic drift; Hardy – Weinberg’s principle; adaptive radiation; human evolution.

Unit-VIII Biology and Human Welfare

Chapter-8: Human Health and Diseases

Pathogens; parasites causing human diseases (malaria, dengue, chikungunya, filariasis, ascariasis, typhoid, pneumonia, common cold, amoebiasis, ring worm) and their control; Basic concepts of immunology – vaccines; cancer, HIV and AIDS; Adolescence – drug and alcohol abuse.

Chapter-10: Microbes in Human Welfare

Microbes in food processing, industrial production, sewage treatment, energy generation and microbes as bio-control agents and bio-fertilizers. Antibiotics; production and judicious use.

Unit-IX Biotechnology and its Applications

Chapter-11: Biotechnology – Principles and Processes

Genetic Engineering (Recombinant DNA Technology).

Chapter-12: Biotechnology and its Applications

Application of biotechnology in health and agriculture: Human insulin and vaccine production, stem cell technology, gene therapy; genetically modified organisms – Bt crops; transgenic animals; biosafety issues, biopiracy and patents.

Unit-X Ecology and Environment

Chapter-13: Organisms and Populations

Population interactions – mutualism, competition, predation, parasitism; population attributes – growth, birth rate and death rate, age distribution. (Topics excluded: Organism and its Environment, Major Abiotic Factors, Responses to Abiotic Factors, Adaptations)

Chapter-14: Ecosystem

Ecosystems: Patterns, components; productivity and decomposition; energy flow; pyramids of number, biomass, energy (Topics excluded: Ecological Succession and Nutrient Cycles)

Chapter-15: Biodiversity and its Conservation

Biodiversity-Concept, patterns, importance; loss of biodiversity; biodiversity conservation; hotspots, endangered organisms, extinction, Red Data Book, Sacred Groves, biosphere reserves, national parks, wildlife, sanctuaries and Ramsar sites.

Case study-based questions are invaluable tools that enrich the learning experience of Class 12 Biology students. They foster critical thinking, decision-making skills, and the practical application of theoretical knowledge. By engaging with case studies, students develop a deeper understanding of biological concepts and their relevance in the real world.

Are the case study-based questions suitable for self-study?

Absolutely! These case study-based questions are designed for both classroom learning and self-study. They are excellent resources for independent practice.

Where I can get Class 12th Biology Case Study Questions?

You can practice the Biology Class 12th Case Study Questions on studyrate.in for free.

Do the case studies cover the entire Class 12 Biology syllabus?

Yes, the case studies encompass various topics from the Class 12 Biology syllabus, providing comprehensive coverage.

Are answer keys provided for the case study-based questions?

Yes, after every questions the Ansswer is provided with detailed explanation

Class 12 biology case study questions chapter 4 reproductive health, class 12 physics case study questions of chapter 14 semiconductor electronics.

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Chapter 9 Human Population and Sustainability

Chapter 9 outline:.

9.1 Overview – Rapid Human Population Growth and its Effect on the Earth

9.2 Age Structure and Population Growth

9.3 human population growth variations among countries.

9.4 Methods for Controlling Human Population Growth

9.5 Sustainability and Environmental Equity Across the Planet

9.6 Indicators of Global Environmental Stress due to Human Population Growth

9.7 Taking The Long View: Human Population Growth and Sustainability from an Evolutionary and Ecological Perspective

9.8 Questions and Answers About Human Population Growth

9.9 Case Study: Human Population Growth

Learning Outcomes:

After studying this chapter, each student should be able to:

9.1 Describe how the rapid rise in human numbers has affected the earth
9.2 Explain how age structure of a human population affects future population growth
9.3 Describe the differences in human population growth among various countries
9.4 Describe the major ways that human population growth can be controlled
9.5 Identify issues related to environmental equity across the planet, and ways to measure this equity, such as the ecological (or carbon) footprint
9.6 Describe measurable changes (indicators) for the earth that identify its condition in relation to human populations
9.7 Describe how the changes wrought by humans relates to historical rates of evolutionary and ecological changes
9.8 Be able to answer major questions about human population growth
9.9 Be able to summarize the current situation regarding human population growth

9.1 Overview- Rapid Human Population Growth and its Effect on the Earth

Concepts of animal population dynamics can be applied to human populations as well . Humans are not unique in their ability to alter their environment in a way that allows for higher populations, but no other organism has made such dramatic changes to our earth and worldwide ecosystems. We have converted large areas of the terrestrial biomes to cultivated fields, covered enormous swaths of our planet with cities, homes, and businesses, and altered the very geology of our planet with dammed rivers and mining operations that have removed mountain s. All of these changes have allowed for human populations to expand to unprecedented numbers, since there is enough food, clothing, and other basic necessities to populate and dramatically alter the far reaches of our planet.

Beavers are well known for their ability to alter their local environmen t, turning streams into ponds with their dams, allowing the beavers and many other aquatic organisms to better survive and reproduce. However, these changes are not nearly as far reaching as changes rendered by humans, and do not have the massive detrimental effects on other species that human changes have wrought.

As earth’s human population increases rapidly, so does the extraction of earth’s resources, some of which are non-renewable, such as fossil fuels. The ability of the Earth to continue to sustain this human population is in question. Long-term exponential growth of the human population carries with it the potential risks of famine, disease, extreme competition for food, water, and shelter, and the ever present risk of large-scale death. Human technology and particularly the use of fossil fuels has caused unprecedented changes to Earth’s environment, altering ecosystems and changing the atmosphere in a way that may be detrimental to all life on our planet.

The fundamental cause of the acceleration of growth rate for humans in the past 200 years has been the reduced death rate due to changes in public health and sanitation , along with vastly more productive agricultural practices . The ability to supply humans with clean drinking water and the proper disposal of sewage and other wastes has drastically improved health in many nations. Medical innovations such as antibiotics and vaccines have also decreased mortality by infectious diseases , one limit on human population growth. Bubonic plague in the fourteenth century killed between 30 and 60 percent of Europe’s population and reduced the overall world population by as many as one hundred million people. Infectious disease continues to have an impact on human population growth, especially in poorer and less medically effective nations. The Covid-19 pandemic, although widespread sometimes tragically deadly, has not put even a detectable dent into the rapid rise in the earth’s human population. Modern science and societal actions have done much to limit the kind of dramatic loss of human life noted during the bubonic plague years. Life expectancy in sub-Saharan Africa declined after 1985 as a result of HIV/AIDS mortality, but the overall human population in that region has continued its relentless rise. Figure 1 show the overall human population growth during the past 1000 years, and differences in growth rate by region of the world:

Figure 1. Changes in the human population over the last 1000 years. Both China and India have populations that have surpassed 1.4 billion, as illustrated for Asia. (Credit: OER Commons – Population and Community Ecology)

Many dire predictions have been made about the world’s human population growth leading to a major crisis called the “population explosion.” In the 1968 book Population Bomb , biologist Paul R. Ehrlich wrote, “The battle to feed all of humanity is over. In the 1970s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate.” While these predictions were fortunately false in most parts of the world, exponential human population growth has led to suffering and deaths in resource poor areas such as sub-Saharan Africa . The population explosion continues unabated, with more people each year using the earth’s limited resources. The most populous country on earth, the People’s Republic of China, imposed a “one child policy” to help limit population growth. This policy was fairly effective, eventually slowing China’s growth rate to a manageable rate, to the point where this policy has been suspended. The availability of family planning methods, and the increase in educated and working females in other countries have both had positive effects on limiting population growth rates and increasing standards of living.

In spite of greater access to birth control methods and improvements i n the education of girls ( two of the most effective methods in curbing rapid population growth !) in many countries of the world , the human population continues to grow. The United Nations estimates the future world population size to be over 11 billion people by the year 2100. There is no way to know whether human population growth will moderate to the point where the crisis described by Dr. Ehrlich will be averted. Important and far-reaching consequence of population growth has been the loss of natural habitats and the degradation of the natural environment. Many countries have attempted to reduce the human impact on climate change by limiting their emissions of greenhouse gases, as formalized in the Paris Agreement on Climate Change, signed by virtually every country in 2016. Although the United States backed out of this agreement under the Trump administration, based on political rather than scientific reasons, the Biden administration rejoined this agreement. We do enter the future with considerable uncertainty about our ability to curb human population growth and protect our environment.

The age structure of a particular human population can be graphed in terms of the proportion of people in different age groups . This information is very informative for predicting future changes in that population. Countries with rapid population growth have a pyramidal shape in their age structure diagrams, showing a preponderance of younger individuals , most of whom will soon reach reproductive age and have more children ( Figure 2 ). This pattern is most often observed in less developed and poorer countries where individuals often have many children, because of economic and social factors, such as the (1) lack of social security income , (2) few educational and career related opportunities for females , and (3) the lack of easily obtained birth control methods.

Age structures of areas with slow or stable growth, including developed countries such as the United States, have a less pyramidal structure , with less young and reproductive-aged individuals in proportion to older individuals. Some countries, such as Japan, Italy and Russia, have not shown an increase in population in recent years, and their population age structure is more cylindrical than pyramidal.

The actual growth rates in different countries are shown in Figure 3 , with the highest population growth rates in less economically developed countries of Africa and Asia.

Link to Learning: Click through this interactive view of how human populations have changed over time

Human population growth rates are quite variable between the nations of the Earth. In general, these variations are related to economic development. With a few exceptions, most nations can be categorized into one of two groups according to their rate of population growth:

(1) The first group consists of countries which have highly developed industrial economies like Japan, Canada, USA, Australia, New Zealand, and the nations of Europe and the former Soviet Union. In these countries the rate of natural increase is less than 1% per year. The population of some of these nations are, in fact, declining (Hungary) or not growing at all (Denmark, Germany, Australia, Greece, and Italy). Finally, it is predicted by demographers that within the next few decades the majority of these nations will be experiencing zero population growth, or even a dip in total population.

(2) The second group consists of less developed nations whose rate of natural increase is greater than 1% per year. These nations are generally found in Central and South America, Africa, and Asia. The demographic graphs shown below illustrate these differences ( Figure 4 ). Many African and Middle Eastern nations such as the Democratic Republic of Congo have growth rates that exceed 3.5 %. Demographers estimate that 90% or more of the increase in the world’s population over the next 50-60 years will occur in this second group of nations. As a result, world leaders and environmentalists have targeted these nations for greater control of population growth.

9.4 Methods for Controlling Human Populations

Populations stop expanding when either (a) the death rate rises to equal the birth rate, or (b) the birth rate declines to the level of the death rate. Artificially increasing death rates is not a humane approach to population control. Countries can, however, support policies to reduce their birth rates. Today, more than 90% of the world’s populations live in countries with programs to reduce birth rates. But according to the World Health organization, as of 2022, only 65% of women across the globe have the ability to utilize some form of birth control.

Demographers have generally recognized three different methods for achieving a reduction in the growth of a population . These methods are:

1. Economic Development 2. Family Planning 3. Socioeconomic Change

1. Economic Development – Demographers have noticed that economic development usually leads to a reduction in a nation’s population growth rate . This reduction is the result of many different factors that are tied to economic prosperity. In general, a higher standard of living reduces the desire for couple to have children because: (1) both sexes are usually actively engaged in the workforce (2) advanced economies offer some type of retirement income (3) the cost of raising children is high (4) children are not considered a part of the family labor force, and (5) education and employment training delays the time period when couples are able to bear children.

2. Family Planning – This method involves any program that provides educational and technological services that help individuals plan the timing of the birth of children. The nature of family planning varies from country to country because of differences in economic development, religion, and culture. Family planning has been very important in reducing birth rates in less developed countries such as China, Indonesia, Brazil, Barbados, Cuba, Columbia, Costa Rica, Fiji, Hong Kong, Jamaica, Mauritius, Mexico, Thailand, Singapore, South Korea, Taiwan, and Venezuela.

In many other less developed countries, family planning programs have not been successful because of economic, religious or cultural reasons. For example, India started to provide family planning programs beginning in 1952 when its population was about 400 million. However, these programs generally failed because of family resistance, especially from the parents of new couples, who wanted as many grandchildren as possible, and could sometimes prevent access to birth control methods. India also lacks a dependable system of social security, making children an important source of support for aging parents. The general lack of female rights, especially in rural communities, and low rates of education for girls, also made controlling family size more difficult. Lastly family planning services were greatly underfunded by state and local agencies. Since 1952 India’s population has tripled to over 1.2 billion, and unless changes occur, will probably surpass China’s large population.

Socioeconomic Changes – Some nations have used economic incentives to reduce fertility rates. China’s “one child policy” gave couples economic rewards for having fewer children. These rewards included salary bonuses, extra food, bigger pensions, improved housing, increased medical care, and free school tuition for the single child. Presently, most countries have lower taxes for families with many children, even though those children are costly to society in terms of educational and health care needs. Couples who decide not to have children or have small families pay more taxes. Changing this financial system, so that there are economic incentives to have fewer children, would encourage a more sustainable future human population .

In conclusion, the many problems related to the rapid increase in human populations can be avoided , if some or all of the above policies are put into place . For societies, these problems include a lack of food and clean water, substandard housing, high unemployment rates, traffic jams, higher rates of disease and crime, and lack of sanitary disposal of human waste. These challenges do not even begin to address the many negative effects of having so many humans on our earth’s ecosystems, including destruction of natural habitats and consequent species extinction, and the lowering of the quality of our air and water.

The following video describes changes in the human population and ways to reduce this rapid growth:

Bozeman Science (2015, Oct 8). Human Population Size [Video – YouTube]. https://youtu.be/QShgk6FrlX0

9.5 Sustainability and Environmental Equity

“Our Common Future”, a report of the World Commission on Environment and Development, published in 1987, is widely credited with having popularized the concept of sustainability , or living in a way that can be “sustained” for the foreseeable future . But for humans to live in a sustainable fashion is very difficult when human population growth increases the daily demand for earth’s limited resources.

The general idea of leaving the earth undamaged for future generations has been noted in many cultures. For example, the principle of “intergenerational equity” is captured in the Inuit saying, “ We do not inherit the Earth from our parents, we borrow it from our children ”. The Native American ‘Law of the Seventh Generation” states that before any major action was to be undertaken, its potential consequences on the seventh generation had to be considered. For the species Homo sapiens that at present is only 6,000 generations old, is increasing in number rapidly, and whose current political decision makers often operate on time scales of months or a few years at most, the thought that other human cultures have based their decision-making systems on time scales of many decades seems very wise.

A common current definition of “sustainable development” comes from the UN World Commission on Environment and Development : “ sustainable development is development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs”. Sustainable development is not a fixed state of harmony, but rather a process of change in which the exploitation of resources, the orientation of the technological development, and institutional change are made consistent with future as well as present needs.” Sustainability, therefore, refers to the sociopolitical, scientific, and cultural practices that will allow for living on this earth without significantly impairing its function for future use.

If the poorer four-fifths of the world population were to exercise their right to grow to the level of the richest one-firth, it would result in ecological devastation . So far, global income inequalities and lack of purchasing power have prevented poorer countries from reaching the standard of living (and also resource consumption and waste emission) of the industrialized countries. But countries such as China, Brazil, India, and Malaysia are catching up fast in their use of resources. If consumption must be reduced for the planet to be sustainable, who will do the reducing? Poorer nations want to produce and consume more and the economies of richer countries promote ever greater consumption-based expansion. Such stalemates have prevented any meaningful progress towards equitable and sustainable resource distribution at the international level.

Figure 5. Share of the world’s consumption of natural resources. The poorest 10% of humans accounted for just 0.5% of consumption while and the wealthiest 10% of humans account for 59% of all the consumption. (Credit: World Bank Development Indicators , 2008)

Ecological Footprint

The concept of an “ ecological footprin t” (EF) was developed by Canadian ecologist and planner William Rees, and uses land as the unit of measurement to assess per capita consumption , production, and the need to discharge wastes . It starts from the assumption that every category of energy and material consumption and waste discharge requires the productive or absorptive capacity of a finite area of land or water. If we add up all the land requirements for all categories of consumption and waste discharge by a defined population, the total area needed represents the Ecological Footprint of that population (whether or not this area coincides with the population’s home region!).

Land is used as the unit of measurement for the simple reason that, according to Rees, “Land area not only captures planet Earth’s finiteness, it can also be seen as a proxy for numerous essential life support functions from gas exchange to nutrient recycling … land supports photosynthesis, the energy conduit for the web of life. Photosynthesis sustains all important food chains and maintains the structural integrity of ecosystems.” Ecological footprint analysis can tell us in a vivid, ready-to-grasp manner how much of the Earth’s environmental functions are needed to support human activities. This analysis also makes visible the extent to which consumer lifestyles and behaviors are ecologically sustainable.

Using the idea of ecological footprint, it has been calculated that the average American needs (conservatively) 5.1 hectares per capita of productive land . If the current global population were to adopt American consumer lifestyles, we would need at least three additional planets to produce the resources, absorb the wastes, and provide general life-support functions to allow the world’s population to function like an American! (with 7.4 billion hectares of the planet’s surface available for human consumption).

While much progress is being made to improve the efficiency of resource use, far less progress has been made to improve resource distribution across the planet. Currently, just one-fifth of the global population is consuming three-quarters of the earth’s resources, as shown by the distorted sizes of various countries (based on resource use) in Figure 6. This illustration shows graphically how regions of the world differ in their per capita ecological footprint.

Global disparities in ecological footprint.

Figure 6. World-wide patterns in resource consumption by country or region. Country sizes are enlarged or shrunken, based on amount of resource use. This map is based on per capita ecological footprints, a common measure of human demand on the earth’s ecosystems. (Source: Geography – WorldPress.com)

The precautionary principle is an important concept in environmental sustainability. A 1998 consensus statement characterized the precautionary principle this way: “ when an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically”. For example, if a new pesticide chemical is created, the precautionary principle would dictate that we presume, for the sake of safety, that the chemical may have potential negative consequences for the environment and/or human health, even if such consequences have not been proven yet. In other words, it is best to proceed cautiously in the face of incomplete knowledge about something’s potential harm. In the same way, it is possible to note some of the indicators of global environmental stress, caused by the current human population of over 8 billion people

9.6 Indicators of Global Environmental Stress due to Human Population Growth:

Forests – Deforestation remains a major issue. Over one million hectares of forest have been lost every year in the last few decades. The largest losses of forest area are taking place in the tropical moist deciduous forests, a zone with some of the poorest communities on earth with high rates of human population growth. Recent estimates suggest that nearly two-thirds of tropical deforestation is due to farmers clearing land for agriculture. There is increasing concern about the decline in forest quality associated with intensive use of forests and unregulated access for damaging activities such as gold mining ( Figure 7 ).

FILE - An aerial view shows a deforested area during an operation to combat deforestation near Uruara, Para State, Brazil January 21, 2023. (REUTERS/Ueslei Marcelino)

Figure 7. An aerial view shows a deforested area during an operation to combat deforestation near Uruara, Para State, Brazil, Jan. 21, 2023. (Credit: Voice of America – Climate Change – Steve Baragona)

Soil – As much as 10% of the earth’s vegetated surface soil is now at least moderately degraded . Trends in soil quality and management of irrigated land raise serious questions about longer-term sustainability. It is estimated that about 20% of the world’s 250 million hectares of irrigated land are already degraded to the point where crop production is seriously reduced. As human populations continue to increase, more land is coming under cultivation, with further risks of degradation.

Fresh Water – Some 20% of the world’s population lack access to safe water and 50% lack access to safe sanitation , a situation that becomes more problematic as human populations increase. If current trends in water use persist, two-thirds of the world’s population could be living in countries experiencing moderate or high water stress in the near future, especially as climate change increases temperatures and reduces precipitation in areas of the world.

Marine fisheries – Over 25% of the world’s marine fisheries are being fished at their maximum level of productivity and 35% are overfished at an unsustainable rate (yields are declining). In order to maintain current per capita consumption of fish with a rising global human population, fish harvests must be somehow increased. Much of this needed increase might come through aquaculture which is a known source of water pollution, wetland loss and mangrove swamp destruction.

Biodiversity — Biodiversity is increasingly coming under threat from development as human populations expand in area , degrading or destroying natural habitats . Pollution from a variety of sources can also reduce biodiversity. A comprehensive global assessment of biodiversity put the total number of species at close to 14 million and found that between 1 – 11% of the world’s species may be threatened by extinction. Coastal ecosystems, which host a very large proportion of marine species, are at great risk with 30% of the world’s coasts at high potential risk of degradation and another 17% at moderate risk.

Atmosphere – The Intergovernmental Panel on Climate Change has established that human activities are having a discernible influence on global climate , warming the earth as more greenhouse gases are released from an increasing human population. Carbon dioxide emissions in most industrialized countries have risen during the past decades and countries have generally failed to stabilize their greenhouse gas emissions, despite efforts to do so.

Toxic chemicals – About 100,000 chemicals are now in commercial use and their potential impacts on human health and ecological function represent largely unknown risks . Persistent organic pollutants released by a rising human population are being widely distributed by air and ocean currents – they are found in the tissues of people and wildlife everywhere, even in artic regions and Antarctica. These pollutants are of particular concern because of their high levels of toxicity and persistence in the environment.

Hazardous wastes – Pollution from heavy metals and other hazardous wastes, especially from their use in industry and mining, is also creating serious health consequences and ecological damage in many parts of the world . This is especially true as developing countries with ever larger populations seek new economic opportunities. Incidents and accidents involving uncontrolled radioactive materials continue to increase, and particular risks are posed by the legacy of contaminated areas left from military activities involving nuclear materials.

Domestic and Industrial Waste — Domestic and industrial waste production continues to increase in both absolute and per capita terms as world populations rise. In the developed world, per capita waste generation has increased threefold over the past 20 years, In developing countries waste generation will likely double during the next decade. The level of awareness regarding the health and environmental impacts of inadequate waste disposal remains rather poor. Inadequate sanitation and a general lack of waste management infrastructure is still one of the principal causes of death and disability for the urban poor.

Of the different forms of life (species) that have inhabited the Earth in its 4.5 billion year history, 99.9% are now extinct. Against this backdrop, the rise of humans with a roughly 200,000-year history barely merits attention. As the American novelist Mark Twain once remarked, “If our planet’s history were to be compared to the Eiffel Tower, human history would be a mere smear on the very tip of the tower”.

But while modern humans ( Homo sapiens ) might be insignificant in geologic time, we are by no means insignificant in terms of our recent planetary impact . Over 40% of the product of terrestrial plant photosynthesis – the basis of the food chain for most animal and bird life – is being appropriated by humans for their use. In addition, over 25% of photosynthesis on continental shelves (coastal areas) is ultimately being used to satisfy human demand. An ever expanding population of humans has appropriated natural resources to an extent that is having profound impacts upon the wide diversity of other species that also depend on them.

Evolution normally results in the generation of new lifeforms at a rate that outstrips the extinction of other species, resulting in continued biological diversity. However, scientists have evidence that, for the first observable time in evolutionary history, one species – Homo sapiens – has upset this balance to the degree that the rate of species extinction is now estimated at 10,000 times the rate of species renewal. Human beings, just one species among millions, are crowding out the other species we share the planet with. Evidence of human interference with the natural world is visible in practically every ecosystem from the presence of pollutants in the stratosphere to the artificially changed courses of the majority of river systems on the planet . It is argued that ever since we abandoned nomadic, gatherer-hunter ways of life for settled societies some 12,000 years ago, humans have continually manipulated their natural world to meet their needs. While this observation is a correct one, the rate, scale, and the nature of human-induced global change — particularly in the post-industrial period — is unprecedented in the history of life on Earth.

There are three primary reasons for this human induced global change:

(1) Mechanization: First, mechanization of both industry and agriculture in the last century resulted in vastly improved labor productivity which enabled the creation of goods and services. Since then, scientific advance and technological innovation – powered by ever-increasing inputs of fossil fuels and their derivatives as populations increased – have revolutionized every industry and created many new ones. The subsequent development of western consumer culture, and the satisfaction of the accompanying disposable mentality, has generated material flows of an unprecedented scale. The Wuppertal Institute estimates that humans are now responsible for moving greater amounts of matter across the planet than all natural occurrences (earthquakes, storms, etc.) put together.

(2) Size of Human Population. The sheer size of the human population is unprecedented. Every passing year adds another 100 million people to the planet . Even though the environmental impact varies significantly between countries (and within them), the exponential growth in human numbers, coupled with rising material expectations in a world of limited resources, has catapulted the issue of distribution to a prominent position. Global inequalities in resource consumption and purchasing power mark the clearest dividing line between the haves and the have-nots. It has become apparent that present patterns of production and consumption are unsustainable for a global population that is projected to reach between 12 billion by the year 2050. If ecological crises and rising social conflict are to be countered, the present rates of over-consumption by a rich minority, and under-consumption by a large majority, will have to be brought into balance.

(3) Chemicals and Materials. Beyond the rate and the scale of change is the nature of that change, which is unprecedented. Human inventiveness across the globe has introduced chemicals and materials into the environment which either do not occur naturally at all or do not occur in the ratios in which we have introduced them . These persistent chemical pollutants are believed to be causing alterations in the environment, the effects of which are only slowly manifesting themselves, and the full scale of which is beyond calculation. CFCs and PCBs are but two examples of the approximately 100,000 chemicals currently in global circulation. (Between 500 and 1,000 new chemicals are being added to this list annually.) The majority of these chemicals have not been tested for their toxicity on humans and other life forms, let alone tested for their effects in combination with other chemicals. These issues are now the subject of special UN and other intergovernmental working groups.

The following video provides ways that our current population can attempt to live more sustainably:

9.8 Human Population – Some Questions and Answers

1, Why is human population an important topic?

The human race has an enormous impact on this planet! We control and modify the Earth more than any other species. How do we meet the needs of human beings and also preserve Earth’s finite resources, biodiversity, and natural beauty? This is the fundamental question of our time, and the challenge is becoming more problematic as we add more people . Meanwhile, in every locality, it’s important to know how fast the human population is growing, so that we can build sufficient sewers, roads, power plants, and schools.

2. Do we know exactly how many people there are in the world today?

No. There are so many people on this planet that counting them up, exactly, is impossible. However, experts believe there are more than 8.1 billion people in the world today. This is a fairly reliable estimate. World population in 2017 is more than 2 times greater than it was in 1960,4 times greater than 1900, and 10 times greater than 1700. After growing very slowly for tens of thousands of years, world population has grown very rapidly in the last few centuries and continues to do so.

3. How fast is the world’s population growing?

In terms of net gain (births minus deaths), we are adding over 200,000 people to this planet every day (which equates to 140 more people EVERY MINUTE). That equates to 70 million more people every year, about the same as the combined population of California, Texas, and New York. Although we have made encouraging progress in slowing the growth rate, any rate of growth is unsustainable in the long term, so we must stabilize the human population soon for the good of future generations.

4. Are there any parts of the world where the human population is not growing?

Yes. Roughly speaking, populations are holding stable in Japan, Western Europe, and North America. Populations are decreasing somewhat in Russia and some Eastern European countries. But the human population is growing either rapidly or very rapidly in almost every other part of the world right now, including India, Pakistan, Bangladesh, South and Central America and most of the Middle East and Africa. In other words, human populations have stabilized where about 2 billion people live and are still increasing very rapidly where 5 billion people live – those who can least afford it. Result: the annual net gain of over 70 million people!

5. I have heard some say the world population crisis is over and that it’s not a problem anymore. Is this true?

No, absolutely not. First of all, 8.1 billion people may well be too many already . Cornell University professor David Pimentel’s research shows that about 2 billion people is the number the planet can sustainably support, if everyone consumes the same amount of resources as the average European (which is less than the average American). Secondly, U.N. experts predict that world population will increase for at least the next 50 years , with a “most likely” prediction of 10 billion people by the year 2050. There probably will be additional growth beyond that.

There’s no doubt that the worldwide average number of children per woman has come down tremendously over the last 50 years – from more than 5 children per woman to about 2.5 per woman . However, (1) the current average is still well above replacement level, which would be 2.1 children per woman, and (2) the number of women having children is about TWICE what it was in 1960. There is also huge “ demographic momentum ,” since half the world’s population is age 24 or younger – either having children now, or poised to have them in the next 10 to 15 years – so that any changes we make today may not have a visible effect until a generation has passed!

Finally, people are living longer all over the world and will continue to do so, with a resultant slowdown in death rates. Thus, there’s a big imbalance in the birth to death ratio: currently about 5 births for every 2 deaths worldwide.

6. So much of the world is still empty space – can’t people just move to less crowded places?

A lot of that space isn’t empty: vast tracts of farmland are necessary to feed the people who live in cities and towns, and forests are necessary to produce wood and oxygen. Much of the land that hasn’t been settled by people simply isn’t habitable: it’s too dry, too cold, or too rocky. Besides, the people who are most overcrowded are struggling to exist on less than a dollar a day… they don’t have the money to move!

7. The United States and other countries with low birth rates let in millions of immigrants each year. Doesn’t this act as a “safety valve” to relieve the population pressure of the faster-growing countries?

Not really. Think of it this way. Each year the U.S. currently allows about a million people to immigrate legally (About 0.5 to 1 million come in illegally.) But each year most countries of the developing world add almost 70 million more people to their numbers, net gain! The one to two million coming into the U.S. hardly makes a dent to relieve the crushing problems created by the almost 70 million more people into these resource-stressed countries – each year!

If we continue letting in as many immigrants for the next 50 years as we have for the past 25, we will absorb only about 4 percent of the population growth from the less-developed countries! Although migration can greatly improve the lives of the immigrants themselves, it is not an effective way to relieve the population growth of the countries they come from.

8. I’ve heard that as population growth slows, countries like the U.S. are going to have to support increasing numbers of dependent elderly people. Don’t we need to have more kids and increase immigration so that we’ll have enough workers to support all these retired people?

No. First of all, people are dependent in their retirement years for only a fraction of the time they’re dependent in their childhood. Right now retirement lasts only half as long as the dependent period before a young person enters the workforce. If trends continue, it may decrease to a third or even a quarter of that youthful dependency. So children are far more expensive to the economy than the elderly! Secondly, population growth has to stop sooner or later, so bringing in more people is not a long-term solution. The long-term solution is to restructure our system so that we don’t need a constant influx of more people. The sooner we stop the increase in numbers, the more intact we leave our resource base for our children of the future.

9. What is meant by “humane” population stabilization?

Controlling birth rates is humane and helpful for families. Population continues increasing because the death rate worldwide dropped much farther than the birth rate. Of course no one wants to see death rates rise. That would be an unthinkably inhumane way to stop population growth! The humane way to reduce population growth is for birth rates to drop and balance with today’s lower death rates. Repeated studies in countries all around the world show that the longer children stay in school, the fewer children they will have. Smaller families can provide more resources for each child, and entire nations benefit when they have fewer children to drain their limited, declining resources. So education is the key to humane population stabilization . ( Figure 8)

One highly successful educational approach involves the use of specially-created soap operas , both on TV and radio that communicate – even to illiterate people – the benefits of having fewer children. These special soaps are currently running on every continent (except Antarctica) and are having an incredible impact to help reduce people’s expectations about their “desired family size.”

Figure 8. Family sizes vary but giving all couples the ability to plan their desired family size is an important factor in reducing overall human population growth. (Credit: Wikimedia Commons)

9.9 Case Studies in Human Population Growth

The growth in our planet’s human population can be mind boggling. Twelve thousand years ago there were about four million humans across the entire planet, less than the current population of Maricopa County in central Arizona. In 1803, the human population reached its first billion. More recently, we have been adding about a billion people to the planet every 12 years. In 2024 the number of humans is about 8.1 billion and continues to rise.

When the People’s Republic of China was approaching a population of one billion in 1979, an official government policy was put into place that limited families to one child ( Figure 9) . Even with this policy in place, the country added almost a half billion more people between 1979 and 2019. This is because in 1979 most families had many children, and as these children went through their reproductive years, the one child from each family still added to the total number. But this increase was about 400 million less than what would have happened without the one-child policy. As population growth began to level off in recent years, the rules were relaxed to allow 2 children per family.

BBC World Service - Witness History, China's One Child policy

Figure 9. Poster promoting the “one child” policy in the People’s Republic of China. (Credit: Wikimedia Commons)

Most countries do not have the political and social will to impose such a policy to limit population growth. Yet in many developed countries, such as Japan, Germany, and Italy, population size has stabilized. Many relate this change to social factors, such as the preponderance of both men and women in the workforce, the decrease in marriages, and the generally higher level of education that women have achieved today. The developed countries of the world have fairly stable populations, and do not generally add to world population growth.

In many countries that are making the change from “developing” to “developed”, such as South Korea, Brazil, and Mexico, population growth rates have decreased as well. Most attribute this to several factors, such as greater educational and career opportunities for women , better systems of social security for retirees so that large families are not needed economically, and easier access to family planning methods . Although the populations of these countries continue to grow, the trend is toward smaller and smaller families. Educating girls as long as possible is closely tied to reduced family sizes.

Today the greatest population growth is noted in some of the poorest countries of the world, primarily in Africa, the Middle East, and parts of Asia. These areas have the lowest levels of education for girls, have cultures that encourage large families and discourage women from working, lack forms of social security for older adults (who must then depend on their family), and often ban or greatly limit birth control methods. Many of these countries, such as Sudan, Afghanistan, Central African Republic, Ethiopia, and Yemen, have populations suffering from starvation already, with limited resources to feed their burgeoning populations.

Counterintuitively, many aid organizations have been working hard to immunize babies and lower the childhood death rate. Although this might seem like it just exacerbates the population problem, studies have shown that women are more willing to have smaller families if they can be more sure that their children will survive to adulthood.

How will human population growth change in the future? Will growth continue until the carrying capacity for humans is exceeded, resulting in starvation, suffering and death? Some biologists point with hope to the lowering of the human population growth rate overall , believing that if this trend continues populations may level off. But most also note that unless social, pollical, and cultural practices change in the near future, many of the earth’s poorest countries are on the way to severe population challenges , with more people than available food and other essential resources.

Attribution

Content in this chapter includes original work created by Lauren Roberts and Paul Bosch as well as from the following sources, with some modifications:

“Biology, 2nd edition” by OpenStax is licensed under CC BY 4.0 / A derivative from the original work

Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0 . Modified from the original by Matthew R. Fisher.

Environmental Biology: an Open Educational Resource ebook Copyright © 2024 by Paul Bosch is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License , except where otherwise noted.

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Case Study Questions for Class 12 Biology Chapter 13 Organisms and Populations

Last modified on: 2 years ago
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Question 1:

Organism P has thick lips and tongue so that it can easily feed on the commonly available spiny plants. Organism Q has thick layer of insulating fat under the skin. It was strong hooves to walk steadily on steep surfaces and lives in burrows during winters. Organism R has bright colours and sticky pads on its fingers and toes. It lives on trees.

(i) Which of the following is correct habitat for organisms P regarding its adaptation? (a) Grassland biome (b) Desert biome (c) Tropical rainforest (d) Tropical deciduous forest

(ii) Which of the following is correct match regarding organism Q and its habitat? (a) Tundra – Polar bear (b) Tropical rain forest – Deer (c) Grassland – Bighorn sheep (d) Desert – Camel

(iii) Which of the following is incorrect regarding organisms R’s habitat? (a) The vegetation shows stratification (b) Epiphytic growth is rich (c) Standing crop is highest (d) Deep rooted shrubs are common due to abundant sunlight

(iv) The dominant plants in habitat where P lives could be (a) Opuntia (b) Nymphaea (c) Deodar (d) both (a) and (c).

(v) Organisms P, Q and R respectively most likely occur in

(a) F, B and A (b) C, A, E (c) A, F and C (d) B, D and A.

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Case Study Questions Class 12 Biology Organisms and Populations

Case study questions class 12 biology chapter 13 organisms and populations.

CBSE Class 12 Case Study Questions Biology Organisms and Populations. Term 2 Important Case Study Questions for Class 12 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Organisms and Populations.

CBSE Case Study Questions Class 12 Biology Organisms and Populations

What are the key elements that lead to so much variation in the physical and chemical conditions of different habitats? The most important ones are temperature, water, light and soil. We must remember that the physico-chemical (abiotic) components alone do not characterise the habitat of an organism completely; the habitat includes biotic components also – pathogens, parasites, predators and competitors – of the organism with which they interact constantly. We assume that over a period of time, the organism had through natural selection, evolved adaptations to optimise its survival and reproduction in its habitat.

Que. 1) Organisms has defined many that they can …………………………………………………………………………… range of conditions.

(d) Reproduce

Que. 3) For the survival and reproduction, organisms are ………………………………………………………………………………………… .

Que. 1)(c) Tolerate.

Que. 5) Answer: Abiotic components such as temperature, soil, water, light and biotic components such as predators, pathogens, parasites and competitors.

Case study 2

Que. 1) Many ocean living organisms cannot live for long in fresh water due to …………………………………………………………………………………. .

Que. 3) (d) 5.

Case study 3

What, then is their source of energy? The spectral quality of solar radiation is also important for life. The UV component of the spectrum is harmful to many organisms while not all the colour components of the visible spectrumare available for marine plants living at different depths of the ocean.

Que. 3) In the photosynthesis process, sunlight is required as a source of ……………………………………………………………………………………. .

Que. 5) Which factor can affect source of light to the organisms?

Que. 4) Answer:Organisms that live deep in the oceans with dark environment are unaware of sun.

Case study 4

Que. 3) According to the evolutionary biologist, mammals are successful because they have ability to maintain ………………………………………………………………………………………. of body.

Que. 5) Answer: Our body will shiver in the winters because outside temperature will be less than our body temperature.

Case study 5

Que. 4) In the polar region, very small animals rarely found. What will be the main reason?

Case study 6

(d) All of them

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Case study in population biology. Sequences and series, find general solution.

Think about a population of individuals which all have two set of chromosomes (as human do). There is one gene that codes for a helping behaviour. This gene has two alleles (an allele is a variant of a gene. Example: Gene: Eye color, Allele1: blue eyes, Allele2: Braun eyes): Allele H (for Helping) and allele NH (for non-helping). I am looking for a function that describes the number of alleles of a given type in an population of infinite size at time t .

For example: N(NH, H, t) is the number of alleles NH in a population that was fixed for H (meaning that only H existed) at time t

At time t=-1 the whole population is fixed for allele H (N(NH,H,-1) = 0) by definition. At time t=0, a mutation had occured and one allele in the population is NH N(NH, H, 0) = 1 by definition. At time t=1, the number of copies of allele NH depends on the fecundity of individuals carrying the mutant allele NH .

In order to find the fecundity of the individuals carrying the different alleles we need to understand what these alleles cause. H causes their a helping behaviour toward their parents. an individual carrying one or two allele H helps its two parents and get a cost c in fecundity. The parents of one individual that carries one or two allele H have a benefit b coming frmo the help they received from one offspring. Therefore the fecundity of someone depends on the number of parents (which is always 2 because nobody ever die in the population (by definition)), the number of offsprings (which vary), the benefit of the behaviour b , the cost of the behaviour c and their own genotype (allele combination) and the genotype of their offspring which itself. We'll consider that half of the offsprings of a mutant carry the mutant allele. The baseline fecundity (from which we substract c or add b ) is g .

b = benefit
g = baseline
Nobody dies!
NH,NH individuals has no cost c (and might have benefits)
H,H and H,NH individuals has a cost c (and might have benefits)
the mutant allele is trasnmitted to half the offsprings

We can as well calculate the number of copies of an allele NH1 in a NH2 population even if carrying the NH1 does not make any difference of behaviour than carrying the NH2 allele

So there are 4 formulas to be found: $$N(NH1, NH2, t)$$ $$N(NH, H, t)$$ $$N(H, NH, t)$$ $$N(H1, H2, t)$$

I think that:

$$N(NH1, NH2, t) = 1 + \sum_{i=1}^{t} \sum_{j=1}^{i} \left(\frac{g}{2}\right)^j$$ Does it seem correct to you? Step by step: $$N(NH1, NH2, t=0) = 1$$ $$N(NH1, NH2, t=1) = 1 + g/2$$ $1$ is the first mutant individual. $g/2$ is its number of offsprings divided by 2 because only half the offsprings carry this NH1 alleles. $$N(NH1, NH2, t=2) = 1 + g/2 + g/2 + \left(\frac{g}{2}\right)^2 = 1 + g + \left(\frac{g}{2}\right)^2$$ $1$ is the first mutant, $g/2$ the alleles in the offspring created during the previous time step, $g/2$ is the copies produced by the first mutant at this time step, and (\frac{g}{2})^2 is the copies of alleles in the offspring of the offsprings of the first mutant!

The other formulas are harder to find for me. I guess it should looks roughly like the one below but I can't figure out. $$N(H,NH,t) = 1 + \sum_{i=1}^{t} \sum_{j=1}^{i} \left(\frac{g-c+b\cdot((i-j)\cdot(g-c)/2)}{2}\right)^j$$

Step by step:

$$N(H, NH, t=0) = 1$$ $$N(H, NH, t=1) = 1 + \frac{g-c}{2}$$ $$N(H, NH, t=2) = 1 + \frac{g-c}{2} + \frac{g-c + b\cdot\frac{g-c}{2}}{2} + \left(\frac{g-c}{2}\right)^2$$

What are the 4 formulas? (one is already found if I haven't made a mistake)

Thanks a lot!

UPDATE: A solution for N(H,NH,t) might be found by solving this question !

sequences-and-series

$\begingroup$ \left( and \right) make appropriate parentheses. It's the difference between $(\frac{a}{b})$ and $\left(\frac{a}{b}\right)$. Also \cdot is the difference between $a*b$ and $a\cdot b$. $\endgroup$ – 2'5 9'2 Commented Sep 17, 2013 at 6:56
$\begingroup$ @alex.jordan Thank you! $\endgroup$ – Remi.b Commented Sep 17, 2013 at 7:10

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CBSE 12th Standard Biology Subject Organisms and Populations Case Study Questions With Solutions 2021

By QB365 on 21 May, 2021

QB365 Provides the updated CASE Study Questions for Class 12 Biology, and also provide the detail solution for each and every case study questions . Case study questions are latest updated question pattern from NCERT, QB365 will helps to get more marks in Exams

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12th Standard CBSE

Final Semester - June 2015

Case Study Questions

'The population of a metro city experiences fluctuations in its population density over a period of time'. (a) When does the population in a metro city tend to increase? (b) When does the population in a metro city tend to decline? (c) If 'N' is the population density at the time 't', write the population density at the time 't + l'.(Delhi 2020).

If in a population of size 'N', the birth rate is represented as 'b' and the death rate as 'd', the increase or decrease in 'N' during a unit time period 't' will be dN/dt = (b - d) x N The equation given above can also be represented as dN/dt = r x N, where r = (b - d). (a) What does 'r' represent in the above? (b) Write anyone significance of calculating 'r' for any population. (c) In a pond there are 100 frogs. 20 more were born in a year. Calculate the birth rate of this population.

There is no natural habitat on earth, which is occupied by a single species. In nature, plants, animals and microbes do not and cannot live in isolation. Interspecific interactions arise from the interaction of populations of two different species. (a) Even a plant species, which makes its own food cannot live alone. Give two examples, where plants depend on other species for survival. (b) Name the type of interspecific interaction seen in each of the following examples. (i) Disappearance of smaller barnacles when Balanus dominated intertidal area of the sea coasts of Scotland. (ii) Clown fish living among the stinging tentacles of sea anemone. (iii) The Wasp species pollinating a fig inflorescence. (iv) Cuscuta growing on hedge plants.

It is generally believed that competition occurs only when closely related species compete for the same resources that are limiting. Give two examples to show that the above statement is not always true.

*****************************************

Cbse 12th standard biology subject organisms and populations case study questions with solutions 2021 answer keys.

(a) Pattern A - Conformers e.g. Amphibians (b) Pattern B - Regulaters e.g. Mammals (c) Homeostasis is the process of maintaining a constant internal environment despite the varying external environmental conditions.

(a) 'r ' represents the 'intrinsic rate of natural increase'. (b) It is an important parameter for assessing the impacts of any biotic and abiotic factor on population growth. (c) The birth rate is 20/100 or 0.5/frog/year.

(a) Plants depend on (i) the soil microbes to break down the organic matter in soil to return the inorganic nutrients for their absorption. (ii) animals for pollination, without which fruits and seeds cannot be formed. (b) (i) Competition (ii) Commensalism (iii) Mutualism (iv) Parasitism

(i) Competition can occur between two unrelated species, when they compete for the same resource, e.g. the visiting flamingoes compete with the resident fishes for zooplanktons in some shallow lakes in South America. (ii) Resources need not be limiting; in interference competition, the feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species, e.g the abingdon tortoise became extinct within a decade after goats were introduced into Galapagos Islands.

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by Burk Krohe | Sep 9, 2024

Eliot Miller conducts research in Costa Rica with the American Bird Conservancy. As the BirdsPlus index manager with the American Bird Conservancy, Miller is working to create an index to value the biodiversity of birds in Central America, the Caribbean and South America. (Photo courtesy of Juan C. Oteyza)

Eliot Miller was in the middle of a six-hour drive to his parents’ home near Boston when he received an email from a Washington Post journalist. The email – out of the blue from one of the nation’s top publications – seemed suspicious, though.

“I asked my wife if she could read it to me,” he recalled. “I was like, ‘Google that guy, this sounds like some weird phishing thing. See if he’s a real journalist.’ She’s like, ‘He seems legit.’”

The journalist in question was Andrew Van Dam, the Post’s Department of Data columnist, and he was interested in Miller’s research on competitive interactions between North American feeder birds. The project, a joint effort between the Cornell Lab of Ornithology and Project FeederWatch , logged nearly 100,000 interactions at bird feeders across the United States and Canada. Those interactions began to unlock a hidden pecking order among hundreds of species of birds.

Miller called his colleague from the car and told him to send the data to Van Dam. Within 48 hours, his article was live, and it began spreading like wildfire across the internet. The playful headline, “ Which birds are the biggest jerks at the feeder? A massive data analysis reveals the answer ,” helped it gain traction on social media.

“It was a pretty cool experience,” Miller said.

Miller, who earned his PhD in biology from the University of Missouri–St. Louis , has carved out a niche as a researcher who likes to tackle big questions by tapping into new data sources.

As a Schmidt Science Fellow at the Cornell Lab of Ornithology, he leveraged citizen scientists in his study of competitive interactions and dominance hierarchies of North American birds. Currently, he’s looking at ways to utilize tools like the Merlin Bird ID app , which he describes as Shazam for birds, as the BirdsPlus index manager with the American Bird Conservancy .

“There’s a million people a day using Merlin,” he said. “There are tons of people using this and opportunities to collect data at a much, much bigger scale. I got really interested in what can we do with that to power our knowledge of what birds are where, how their populations are doing and how their trends are doing.”

As a young bird enthusiast, Miller couldn’t have anticipated so many other people would be interested in birdsongs, much less that ornithological research would go viral.

“I was real secretive about birding through junior high and most of high school,” he said. “It wasn’t really a cool thing to do.”

Miller traces his interest in the subject to his father and grandfather who were avid birdwatchers. He recalls writing a list of all the birds he saw in a day near his home in Amherst, Massachusetts, when he was about 8 years old. Trips to visit his grandfather in California were always a cause for celebration because he would get to spot different species endemic to the Western United States.

When he was 11 years old, his father took him and his grandfather on a trip to Belize to go birdwatching. Exploring the country’s tropical rainforests and vibrant biodiversity was a transformative experience for a budding biologist. Ultimately, the trip presaged his future career and the tropical terrain he would tread again as a researcher.

“I had this notebook – the lodge would give you a little checklist to check your birds off – and there was a notes section at the back.” he said. “In the notes section, I’d written Cornell Lab of Ornithology. It was spelled all wrong. I don’t know if somebody told me about it, but that was the first time it crossed my radar.”

Miller completed his undergraduate education in biology at Vassar College, where he began working in the field during summers. Miller realized he could hone his professional skills doing bird surveys while getting paid to spend time outdoors. As far as he was concerned, it was a win-win situation.

“It was just all about finding places I could get paid to go, somewhere really exotic,” he said. “I wasn’t filthy rich, but I would take less money if I got to go to Ecuador or something. So, it was a balance. It played out for a few more years after college. I’d go home and wait tables and landscape and work two jobs, and then go back to the tropics for six months.”

That work took him to destinations throughout the Americas, including Canada, Costa Rica, Ecuador and Mexico. It was exciting, but eventually, he decided to bolster his career prospects by pursuing a PhD.

Miller came to UMSL based on the strength of its tropical biology program and studied under renowned ecologists and ornithologists Bob Ricklefs and Bette Loiselle . During his time at the university, he was affiliated with the Whitney R. Harris World Ecology Center , and his doctoral research focused on the foraging ecology of honeyeaters in Australia.

After graduation, Miller’s field experience and work at UMSL helped land him a short-term National Science Foundation fellowship in Idaho. From there, he secured a postdoctoral fellowship with the Cornell Lab of Ornithology.

In Idaho, he had begun exploring how to collect data on a large scale by partnering with citizen scientists – hobbyist, nonprofessional researchers like birdwatchers. Historically, projects that utilize citizen scientists have been somewhat one-dimensional, limited to recording “what, where, when.”

“I was really curious, what else can we get citizen scientists doing?” Miller said. “I had this idea that people really like fights and have a weird interest in watching them. That always happens at bird feeders, so you can get a ton of data about who’s fighting with whom and who’s winning.”

At Cornell, Miller took that idea and ran with it. He partnered with Project FeederWatch, a long-running annual survey of North American birds from November to April, to have birdwatchers across the continent judge aggressive interactions between birds at feeders. The novelty of project even helped it obtain NSF funding.

The team working on the project ran thousands of recorded interactions through a Bradley–Terry model – a probability model used to determine the ranking of variables based on pairwise competitions – to synthesize them into a power ranking. In some cases, the results were expected, but in others, there was more nuance below the surface.

“The first, most obvious one, which is expected, is bigger birds tend to win,” Miller said. “It’s not rocket science. If the turkey fights, it’s gonna win, right? There was also some other stuff that you might call obvious in retrospect, but it wasn’t obvious out of the gate. Woodpeckers, for example, are really dominant for their body mass.

“Downy woodpeckers, they probably weigh about the same amount as a cardinal, but the downy woodpecker is way more dominant. It probably has to do with bill length and the fact that they hammer on trees for a living, basically. And cardinals just crush seeds. Usually, when they fight, the cardinal just goes away, loses, so to speak.”

At the American Bird Conservancy, Miller has turned his attention to birds in tropical regions of Central America, the Caribbean and South America. In his current role, he’s working to create an index to value the biodiversity of birds in working lands in those regions.

He plans to deploy autonomous recording units consisting of a small waterproof box with a battery, microphone and SD card in 16 countries within the next two years. Once they’re set up, they’ll make a one-minute recording every five minutes. With the help of artificial intelligence tools, similar to the Merlin Bird ID app, ABC will be able to parse that massive amount of data.

“You just send it through, and it comes back and tells you what birds are where,” Miller said. “You can start making these models and quantifying the biodiversity retained.”

ABC is also helping farmers transition from sun-grown to shade-grown coffee and to plant more native hardwood trees on rubber plantations. Presumably, that will increase biodiversity, and Miller is on a mission to help prove it.

“It’s hard to put a number on that, and that means it’s hard to attract, say, corporate investment into conservation,” he said. “It would be really cool, for example, for Walmart to be like, all our coffee is shade-grown, and we estimate that that protects 300 million birds a year.”

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People with dementia may be at higher risk of having suicidal thoughts

Download PDF Copy

People with dementia are more likely to have suicidal thoughts but are not necessarily more likely to attempt or die by suicide than the general population, finds a new study led by UCL researchers.

The study, published in Ageing Research Reviews , analyzed 54 studies that investigated various aspects of mental health - including the prevalence and risk of suicide - in people with dementia, between 1991 and 2023.

Dementia is an escalating global health challenge, affecting an estimated 55 million people worldwide. Alongside impacting cognitive abilities, people with dementia often experience debilitating neurological and psychological symptoms such as depression, apathy, aggression and anxiety.

These symptoms can sometimes lead to heightened emotional distress and, in some cases, suicidal ideation.

The researchers pooled data from 20 studies that reported on suicidal thoughts in people with dementia, that involved more than 1.5 million people. They found that 10% of people with dementia had experienced suicidal thoughts compared to the World Health Organization's estimate of 2% for the general population.

Those with moderate dementia were more at risk of suicidal ideation than those with mild dementia.

However, after reviewing data from more than 3.7million people with dementia, the researchers found that the prevalence of attempted suicide or death by suicide was approximately the same as the prevalence found in the general population- with 0.8% of people with dementia attempting suicide within a two-year period.

The team found that 0.1% of people with dementia died by suicide, and younger people with dementia were about three times more likely to be affected than those who were older.

Even though men were less likely to report suicidal thoughts they were significantly more likely to attempt suicide and almost three times more likely to die by suicide than women.

Dementia is a growing global health issue as more people live long enough to develop it. People with dementia may be at higher risk of having suicidal thoughts and in particular certain groups such as men and younger people with dementia may be more at risk of dying by suicide, but this field has not been well studied, The current NICE guidelines for the assessment, management and support of people living with dementia do not mention suicidality in this population or address how to assess or manage this risk. This means that clinicians do not routinely assess or actively manage this risk. This review highlights the importance of providing mental health support and suicide prevention in dementia care, with a focus on age, the severity of symptoms, and sex." Dr. Roopal Desai, Lead Author, UCL Psychology & Language Sciences

In light of the study's findings, the researchers are now calling on clinicians and caregivers to be vigilant in assessing the emotional well-being of people with dementia, in order to ensure timely support and the safety of patients.

Study limitations

The study examined various ways people expressed suicidal thoughts and involved both clinical and community samples, which can influence incidence rates.

The researchers were also unable to analyse all the risk factors for suicide due to a lack of information from the existing studies.

In addition, the findings do not consider different subtypes of dementia (i.e. frontotemporal dementia may pose a higher suicide risk due to behavioural changes and aggression).

University College London

Desai, R., et al . (2024). Suicide and dementia: A systematic review and meta-analysis of prevalence and risk factors. Ageing Research Reviews . doi.org/10.1016/j.arr.2024.102445 .

Posted in: Medical Research News | Medical Condition News

Tags: Anxiety , Brain , Dementia , Depression , Frontotemporal Dementia , Global Health , Language , Mental Health , Psychology , Research

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Methodology
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Published: 10 September 2024

CUREMA project: a further step towards malaria elimination among hard-to-reach and mobile populations

Alice Sanna 1 ,
Yann Lambert 1 ,
Irene Jimeno Maroto 1 ,
Muriel Suzanne Galindo 1 ,
Lorraine Plessis 1 ,
Teddy Bardon 1 ,
Carlotta Carboni 1 ,
Jane Bordalo 2 ,
Helene Hiwat 3 ,
Hedley Cairo 3 ,
Lise Musset 4 ,
Yassamine Lazrek 4 ,
Stéphane Pelleau 5 ,
Michael White 5 ,
Martha Suárez Mutis 6 ,
Stephen Vreden 7 &
Maylis Douine 1

Malaria Journal volume 23 , Article number: 271 ( 2024 ) Cite this article

Metrics details

In most countries engaged on the last mile towards malaria elimination, residual transmission mainly persists among vulnerable populations represented by isolated and mobile (often cross-border) communities. These populations are sometimes involved in informal or even illegal activities. In regions with Plasmodium vivax transmission, the specific biology of this parasite poses additional difficulties related to the need for a radical treatment against hypnozoites to prevent relapses. Among hard-to-reach communities, case management, a pillar of elimination strategy, is deficient: acute malaria attacks often occur in remote areas, where there is limited access to care, and drugs acquired outside formal healthcare are often inadequately used for treatment, which typically does not include radical treatment against P. vivax . For these reasons, P. vivax circulation among these communities represents one of the main challenges for malaria elimination in many non-African countries. The objective of this article is to describe the protocol of the CUREMA study, which aims to meet the challenge of targeting malaria in hard-to-reach populations with a focus on P. vivax .

CUREMA is a multi-centre, international public health intervention research project. The study population is represented by persons involved in artisanal and small-scale gold mining who are active and mobile in the Guiana Shield, deep inside the Amazon Forest. The CUREMA project includes a complex intervention composed of a package of actions: (1) health education activities; (2) targeted administration of treatment against P. vivax after screening against G6PD deficiency to asymptomatic persons considered at risk of silently carrying the parasite; (3) distribution of a self-testing and self-treatment kit (malakit) associated with user training for self-management of malaria symptoms occurring while in extreme isolation. These actions are offered by community health workers at settlements and neighbourhoods (often cross-border) that represent transit and logistic bases of gold miners. The study relies on hybrid design, aiming to evaluate both the effectiveness of the intervention on malaria transmission with a pre/post quasi-experimental design, and its implementation with a mixed methods approach.

Conclusions

The purpose of this study is to experiment an intervention that addresses both Plasmodium falciparum and P. vivax malaria elimination in a mobile and isolated population and to produce results that can be transferred to many contexts facing the same challenges around the world.

In 2022, the worldwide number of malaria cases was estimated at 249 million, causing approximately 608000 deaths [ 1 ]. While global scaling-up of malaria control interventions led to apparent decrease between 2000 and 2015, the main indicators of morbidity and mortality remained broadly stable between 2015 and 2020, and even increased after the Covid-19 pandemic. This suggests that the limits of current strategies have been reached and that new methods need to be developed, both in terms of technology and of operational approaches, to achieve the target 90% reduction of malaria morbidity and mortality by 2030, as set by WHO Global malaria technical Strategy [ 2 ].

Plasmodium vivax is the second malaria parasite species by order of incidence on a global scale, with an estimated 6.9 million cases per year in the World [ 1 ]. It is currently responsible for two thirds of malaria cases in the Americas, with up to 80% relapses [ 3 ]. The only means of prevention of relapses is a radical pharmacological treatment by a cure of 8-aminoquinoline drugs (primaquine for 7 or 14 days or, recently, a single-dose of tafenoquine) [ 4 , 5 , 6 ]. Testing for G6PD deficiency (a red blood cell hereditary condition) is recommended before administering this radical treatment, in order to avoid serious adverse reactions such as haemolysis [ 5 ]. No direct diagnostic test is available to detect P. vivax hypnozoites carriage, meaning that it is impossible to identify a latent infection when blood-stage parasites are no longer detectable [ 7 ]. For all these reasons, territories endemic for P. vivax usually struggle with access to radical treatment for all affected individuals [ 8 ].

In territories progressing toward malaria elimination, a typical transition in epidemiology is often observed: spatial heterogeneity becomes more marked, the proportion of cases caused by P. vivax more important, and adult males become the most affected sub-population [ 9 , 10 , 11 ]. Spatial strata characterized by more intense transmission combine favourable environmental characteristics (including recent anthropization of natural environments), geographic isolation, human mobility (particularly in cross border contexts), and often occupational and socio-economic and/or political vulnerability [ 9 , 10 , 12 , 13 , 14 ]. Indeed, among mobile and isolated populations, case management, is often deficient: attacks often occur in remote areas with no access to care and treatment is often inadequate with smuggled drugs, usually not including P. vivax anti-hypnozoite treatment [ 15 , 16 ]. These individuals might be asymptomatic carriers of Plasmodium, due to acquired partial immunity [ 17 , 18 , 19 ] and thus contribute to sustaining transmission in remote rural or forested areas, but also in urban and peri-urban settings through continuous spillover [ 20 , 21 , 22 , 23 , 24 ]. In this light, populations living in remote areas represent hotspots of P. vivax transmission, and Plasmodium clearance among mobile and isolated groups is the ultimate challenge for malaria elimination in many low and medium transmission settings [ 9 ]. Plasmodium vivax patients should be rationally treated with radical therapy; irrational drug use, such as with smuggled drugs is discouraged.

In the Amazon region, persons involved in artisanal and small-scale gold mining (ASGM) are a typical hard-to-reach population [ 25 ]. They live and work for weeks or months deep in the rainforest, where the density of malaria vectors ( Anopheles spp.) is high [ 20 , 25 , 26 ] . As they are often involved in informal or illegal mining, national health systems may be unable to implement specific interventions to reach them, due to unfavourable regulations or an unsupportive political environment. These miners regularly move to other areas in search of more productive sites, or for logistical or personal reasons. Gold mining areas are often characterized by high malaria endemicity, and miners can fuel malaria reintroduction in low burden areas [ 25 , 27 , 28 , 29 , 30 ]. Their mobility is often cross-border or transnational in the Amazon region, making it a complex challenge to individual as well as public health management [ 25 , 28 , 31 ].

French Guiana (FG) is the only territory in the European Union where indigenous transmission of malaria is currently ongoing. It is located within the Guiana Shield and shares land borders with Brazil (Amapá State) and Suriname [ 32 , 33 ]. FG, Amapá State and Suriname share a common decreasing malaria incidence, a predominance of P. vivax and transmission mainly concentrated in gold mining areas and in some cases in remote indigenous communities [ 32 , 34 , 35 ]. In this region, persons involved in ASGM ( garimpeiros) are mainly of Brazilian origin, and are highly mobile across the Guiana Shield [ 25 , 28 , 31 , 36 , 37 ]. The World Health Organization (WHO) included Suriname and FG among the territories that could defeat malaria by 2025 (E-2025 initiative) [ 1 ].

A first public health intervention research project, Malakit, was implemented from 2018 to 2020 at the borders between FG and Brazil and Suriname to address access to malaria diagnostic testing and good quality treatment for persons working in remote and illegal mines in FG [ 20 , 36 , 38 , 39 ]. The project’s intervention consisted in making available a kit, including malaria rapid diagnostic tests (RDTs) and an artemisinin-based combination therapy (ACT), as well as a training on how to correctly self-test and self-treat delivered at the garimpeiros ’ cross-border staging areas by community health workers (CHWs). This study, evaluating an innovative intervention, has constituted an urgent and pragmatic response to the risk of emergence of resistant P. falciparum linked to inappropriate use of smuggled ACT doses among the target population [ 15 , 40 , 41 ]. The project’s strategy showed to be successful: the proportion of garimpeiros reporting proper treatment with an ACT after a positive RDT significantly increased (OR = 1.8 95% CI [1.1–3.0]) [ 39 ]. Mathematical modelling estimates that the Malakit project helped prevent 43% of the cases imported from FG to Brazil and Suriname [ 39 , 42 ]. However, the Malakit intervention does not offer a solution to prevent P. vivax relapses: while the overall malaria prevalence and incidence decreased, the proportion of P. vivax infection among the target population increased after the intervention (from 42 to 85% among persons recruited at the FG-Suriname border, and from 85.7% to 100% at the FG-Brazil border) [ 39 ].

Recently, several tools have joined the arsenal against P. vivax malaria . Tafenoquine has been approved for P. vivax radical cure by health authorities from an increasing number of endemic countries [ 43 ]. This drug has stricter contraindications because of its long half-life and a higher haemolytic risk in case of G6PD deficiency [ 44 , 45 ], but its use at a single-dose presents an important advantage compared to primaquine, which is subject to sub-optimal adherence even with a short 7 day regimen [ 46 , 47 ]. A recent point-of-care device for quantitative evaluation of G6PD activity [ 48 , 49 , 50 ] has performed very well in identifying severe and intermediate G6PD deficiency compared to the gold standard. It has been successfully tested in the field in Asian countries [ 51 , 52 , 53 ] and in Brazil [ 54 , 55 , 56 ], and allows for field implementation of tafenoquine treatment. The roll out of this innovative technology in the routine of health care services is currently being planned and implemented in the territories of the Guiana Shield.

Considering the evolution of the malaria epidemiology with a predominance of P. vivax among garimpeiros , the importance to tailor specific strategies to reach this population, and the availability of new tools for P. vivax radical cure, a new interventional project called CUREMA ( Radical CURE for MAlaria among highly mobile and hard-to-reach populations in the Guiana Shield ) has been designed. The aim of this project is to evaluate an intervention targeting malaria elimination ( P. falciparum and P. vivax ) among the persons working in ASGM in the Region.

This article presents the protocol of the CUREMA project.

The CUREMA project is a mixed-methods interventional, multicentric, international study.

It aims at evaluating a new public health intervention targeting malaria among hard-to-reach and mobile populations [ 57 ]. The main objectives of the project are:

To evaluate the impact of the intervention on malaria transmission among persons involved in ASGM in the Guiana Shield.

To evaluate the implementation of the intervention and to identify obstacles and levers to inform on transferability and scaling-up.

Intervention’s target population

The target population of the intervention is represented by people actively involved in ASGM in the Region. Active participation in gold mining is defined as having worked in a gold mine in the last 12 months, or planning to enter a gold mine in the next month. As described in previous publications [ 20 , 36 , 38 ] the population is predominantly male (around three quarters), adult, and is involved in a variety of activities: the various aspects of metal extraction and site management, support services, such as cooking, sales (through small grocery stores or as mobile vendors), transport of people or goods (by river or land, with portage or ATVs), mechanics, wood removal for site structures, and sex work.

Criteria for participation in the study are summarized in Table 1 .

Study settings

The study is carried out in Suriname and Brazil (Amapá State). The study’s facilities and inclusion sites are mainly located at cross-border points (towns or small informal settlements located on the riverbanks) along the two river borders of FG, considered crossing points and logistics hubs for the target population, where can be found shops, bars and accommodation facilities mainly receiving garimpeiros . These are “neutral” places where the public is easy to meet and not in a clandestine situation. They are illustrated in Fig. 1 .

Map illustrating the study locations (red dots) and the respective project’s field teams

CUREMA intervention and its implementation strategy

Intervention.

The CUREMA intervention is a package of actions including three components: two different services offered to participants, with a common core component of health education.

The health education activities focus on malaria: its causes, means of prevention, the main differences between P. falciparum and P. vivax , and the importance of a complete anti-malarial treatment. It is provided to participants as part of the inclusion process in the study, and to the community during out-reach activities.

Each participant, after collection of written and informed consent, is able to choose whether to participate in one or both services: the “radical cure” and the “malakit”. During the inclusion process (Fig. 2 ), the participants answer a short questionnaire designed (1) to collect socio-demographic and occupational data, and (2) to assess eligibility criteria to the service(s) selected by the participants.

Inclusion process for the CUREMA intervention

The “radical cure” represented by the treatment of asymptomatic individuals considered at risk of carrying P. vivax hypnozoites. The objective of this service is to prevent relapses and thus to reduce further transmission of this parasite.

Individuals considered at risk of carrying P. vivax are identified through questions from the inclusion questionnaire, regarding their recent exposure to malaria. Contra-indications to radical cure are also documented within the questionnaire (breastfeeding, history of allergy or other side effect to 8-aminoquinoline or chloroquine, severe mental health disorders history) and point-of-care tests: quantitative assessment of G6PD activity level performed with capillary blood through STANDARD G6PD tests from SD Biosensor performed by CHWs, and urine pregnancy test for women of childbearing age.

Eligible participants receive a three-day course of chloroquine associated to an 8-aminoquinoline drug (a 7 day course of primaquine 0.5 mg/kg/day adjusted by weight categories, or a unique dose of 300 mg of tafenoquine). The treatment is started immediately, and the first dose uptake is directly observed. During the inclusion process participants receive oral and written instructions on how to take the tablets, potential side effects and what to do in case of an adverse event (AE), including the potential need to seek urgent care (Fig. 3 ).

Kits for participants to the CUREMA intervention: A self-test and self treatment kit, called malakit, consisting in a test pocket (green) and a treatment kit (pink), both illustrated in order to guide kit use by illiterate participants; B radical cure kit, consisting of a treatment pocket (with numbered Ziploc with daily treatment doses) and illustrated flyers informing on posology, contra-indication and potential side effects

Adherence and safety data are collected by a 14 day follow-up. Follow-up visits (planned at 2, 5 and 14 days after the start of the treatment) are ensured by several tools tailored to the context and to the usual short-term mobility of the target population: an in-person or phone follow-up by CHWs, or self-reporting via a smartphone application. In both cases the follow-up consists in a short questionnaire exploring the main symptoms of significant AEs (haemolysis, allergy, cardiac rhythm modifications). In order to detect any further serious adverse events, participants are also asked about their perceived general state of health, and whether they have had to seek medical attention since starting treatment. In case of positive answer to either one of these questions, the participant is invited to stop the treatment and to seek care at the nearest health facility; an interview is also performed by one of the physician investigators of the study and, if deemed necessary, further clinical and biological explorations are proposed to assess (1) the severity of the AE and (2) the causal link with the medications delivered in the context of the study. Serious adverse events (e.g. severe haemolysis) are collected and reported immediately to the relevant authorities, the sponsor's pharmacovigilance team and the Data and Safety Monitoring Board of the study.

The 8-aminoquinoline initially implemented at inclusion sites is primaquine; tafenoquine will be gradually introduced in the inclusion process as soon as the field procedures of inclusion and follow-up are robust and the drug available (donation by GSK).

The malakit represented by the delivery, after appropriate training, of a self-testing and self-treatment kit. The objective of this service is to provide access to quality diagnosis and treatment for episodes of symptoms compatible with malaria that occur in situations of extreme remoteness from health services. The kit is composed of two illustrated plastic pouches. The diagnostic pouch contains three malaria rapid diagnostic tests Bioline malaria rapid tests by Abbott, chosen because they are prequalified by the WHO, have individual packaging and are capable of detecting the malaria species circulating in the region; the models used depend on the purchasing possibilities of the countries concerned according to the local regulations. The treatment pouch contains a blister of paracetamol, a full course of artemether-lumefantrine (20 mg/120 mg) and a single low dose of primaquine (15 mg) to target P. falciparum gametocytes and prevent onwards transmission (Fig. 3 ) [ 39 ]. Participants receive training about malaria symptoms, how to correctly perform rapid tests and how to follow the treatment. Knowledge assessment is carried out after the training, and participants have to perform and interpret a self-test correctly in order to be eligible to receive the kit.

Implementation strategy

The aim of this study is to evaluate both the intervention and its implementation under the conditions relevant to the target population and context. It is, therefore, essential to describe in systematic manner the main features of the chosen implementation strategy [ 58 ].

The intervention is offered by community health workers speaking the same language and belonging (or being near) to the community itself. The study’s CHWs have a similar profile to that of health workers recruited by a number of malaria control programmes, particularly in remote areas. Field activities are implemented through civil society partner organizations, who hire the CHWs and are responsible for sites’ logistics: in Suriname by the SWOS foundation, which has the purpose of developing the scientific research in health in the country; in Brazil through the NGO DPAC Fronteira, whose main activity is social mediation in health and community development at the French-Brazilian border [ 59 ].

Dose and temporality:

In the context described above, the strategy takes advantage of the regular mobility of the potential participants between the inclusion sites and gold mines, approaching the target population where and when they are easily accessible, thus overcoming the obstacles presented by the isolation of the community at their gold mines, which are often inaccessible to health teams due to security and regulatory constraints. Therefore, they will be reached on an ongoing basis rather than through one-off operations. The expected inclusion rate is between 25 and 50 participants per site per month, allowing a gradual increase of the coverage of the study’s target population. The intervention is planned to be offered for 20 months.

Additional features of the implementation strategy should be mentioned:

Training and supervision at the core of the implementation strategy:

CHWs have received comprehensive initial training allowing them to correctly carry out inclusions and follow-up [ 59 ], and benefit from continuous refresher training. The coordination team and the field supervisors ensure the fidelity of inclusions and follow-up through supervision visits and standardized evaluation, activity assessment, stocks follow-up, management of operational issues. As a part of this process, quality assurance procedures for STANDARD™ G6PD analyzer are implemented according to the PATH G6PD Operational Research Community of Practice (GORCoP) [ 60 ], and supervised inclusion processes are regularly realized including a checklist evaluating the fidelity in the G6PD testing.

Tailored tools elaborated through a participatory approach:

The content of the participants’ training as well as the information, education and communication (IEC) tools elaborated in the context of the project are the fruit of pre-intervention qualitative research about malaria knowledge and health perceptions, available at the project’s website [ 61 ]. They have been designed with the participation of the target population, to be acceptable, relevant and understandable.

An information system that supports the inclusion and follow-up activity:

The inclusion and follow-up process are supported by “smart” electronic questionnaires filled-in on tablets by the CHWs. The information system of the former Malakit project was adapted to meet the needs of CUREMA [ 62 ]. The questionnaires, based on the Open Data Kit (ODK) Collect Android application, can be used offline, and according to the information entered by CHWs, advise them on the next steps of the inclusion process, on the eligibility of participants to either services of the project, or on specific actions that need to be taken. Thanks to the weekly upload of inclusion and follow-up data to the study servers an ongoing monitoring and evaluation of data quality is performed by the coordination team.

Moreover, a tailored smartphone application has been developed for the project. In this app, which can be used offline, participants are able to find educational videos. For participants receiving radical cure, popup notifications appear on the screen and prompt follow-up questionnaires. Data can be collected offline and sent to the study servers whenever an internet connection becomes available. Satellite based wireless connections are increasingly available even in remote gold mining sites, and regularly accessed for personal purposes by the gold miners [ 63 ].

Design and outcomes

The CUREMA study relies on a hybrid design, assessing both population-scale effectiveness of the intervention and its implementation [ 57 ], to facilitate its translation into programme action. More precisely, this will be a type I hybrid study, testing effects of an intervention on relevant outcomes while observing and gathering information on implementation (Table 2 ).

The effectiveness of the intervention on malaria transmission is evaluated by a pre/post quasi-experimental design. Therefore, the main outcome of the study is the variation of the proportion of people carrying Plasmodium spp. parasites by ultrasensitive PCR measured before and after the intervention. To support the interpretation of this outcome, the evolution of malaria epidemiology in the region over the study period will be assessed by: (1) data from the surveillance systems of the three countries involved in the project; (2) the analysis of the evolution of serologically positivity rate for P. vivax ; (3) collection of dry blood spot (DBS) samples for each participant in the intervention (usPCr and Pv serology). This will allow a modelling of malaria epidemiological fluctuations occurring in the region during the intervention.

The main outcome chosen to evaluate the implementation of the intervention is its penetration [ 64 ] within the target population, i.e. the proportion of the target population included in the intervention at the end of the study period. The effectiveness of the intervention is in fact closely dependent on its actual execution and on the coverage of the target population. To put this outcome into context and to provide food for thought about possible scale-up or transferability, acceptability, safety, appropriateness, feasibility, fidelity and sustainability will be assessed by quantitative data and qualitative surveys [ 64 ].

The underlying assumptions about how these objectives should be achieved are set out in the logic model proposed in Fig. 4 .

Intervention's theory

Data sources

Data for evaluation are provided through different study components which articulation is illustrated in Fig. 5 .

CUREMA project design and timeline

The intervention:

Inclusion and follow-up questionnaires provide information on the number of participants, their socio-demographic and occupational profile, the actual delivery of the services (dependent on participants’ choice and eligibility), the adherence to the treatments and their safety. DBS are collected for all the participants undergoing fingerpick for G6PD test or self-test training. Data generated from participants follow-up and from AE investigations will allow to produce evidence on the safety of the intervention. For the intervention, no sample size has been defined from a statistical perspective: its target is to include as many persons as feasible. Between 2500 and 5000 participants are expected during the study’s period, in the same order of magnitude as the Malakit project [ 39 ]. A non-inclusion registry collects anonymous information about individuals that did not wish to participate in the study or did not meet the inclusion criteria, contributing to the acceptability evaluation. Important additional data for the evaluation of the implementation are the information produced by the supervision activities (check-lists, audits) and the evaluation of the training of facilitators performed during the initial session [ 59 ].

The pre-and post-intervention epidemiological surveys:

Two cross-sectional surveys take place at inclusion sites before and at the end of the intervention implementation, during the same period of the year (during the last quarters of 2022 and 2024) in order to limit potential biases associated with seasonality. The participants are selected among individuals having left an illegal gold mine located in FG within the past seven days [ 20 , 39 ]. These surveys include a detailed questionnaire about recent malaria history and mobility, a clinical examination and a venous blood sample. The proportion of malaria parasite carriage will be assessed by a Plasmodium us-qPCR (ultra-sensitive quantitative polymerase chain reaction) [ 65 ], with species-specific probes for P. vivax , P. falciparum and Plasmodium malariae asexual and sexual forms. Plasmodium vivax serology by Luminex assay will be performed following methodology described by Longley et al. [ 66 ], in order to assess recent (and thus potentially latent) infections, as well as medium-term transmission trends [ 66 , 67 , 68 , 69 ]. The biological collection will be stored at biobank Centre de Ressources Biologiques Amazonie in Cayenne.

The sample size requirements have been calculated based on the univariate analysis of the main effectiveness outcome: with a hypothetic pre-intervention all-species prevalence of 2%, and a target 75% reduction after two years of intervention (leading to a post-intervention prevalence of 0.5%), 860 participants should be included in each survey in order to perform this comparison with a two-sided 0.05 alpha risk and a 0.8 beta risk.

Qualitative research :

Qualitative surveys are performed before, during and after the intervention by a social science researcher. The aim of these surveys is to support community engagement and to analyse the specific constraints and levers of the intervention under study and the pre-elimination context, to understand which elements could influence the success or the failure of the intervention and implementation strategy under evaluation. The qualitative research addresses three groups involved in the study: (i) the target population of the intervention, (ii) the field workers who participate in the inclusion and supervision activities, (iii) scientific and institutional (technical officers and decision-makers) stakeholders of the study.

Interviews and discussion groups are proposed at different times to all stakeholders of the study. Participant and non-participant observation are conducted to collect descriptive data on context, behaviours, interactions and dynamics, experiences, and will allow researchers to better describe and interpret the data.

National and regional epidemiological surveillance data:

Data from the malaria programmes surveillance systems of French Guiana, Brazil and Suriname regarding cases notified, according to their origin and (while available) occupational category will allow to evaluate the general context of the regional malaria epidemiology.

The Centre d’Investigation Clinique Antilles-Guyane is an INSERM (Institut National de la Santé et de la Recherche Médicale) research unit based at Cayenne Hospital and is the sponsor of the CUREMA study. Key scientific partners include the SWOS and the Fundação Oswaldo Cruz (FIOCRUZ): these institutions host the principal investigators responsible for inclusions in Suriname and Brazil, respectively. Major scientific collaborations with the Pasteur Network support the project, providing expertise in the molecular biology and immunology of malaria. In Brazil, collaboration with the NGO DPAC-Fronteira brings to the project significant experience in social mediation, health education and mobilization, and empowerment of vulnerable communities.

The project is supported by the health authorities competent for the three territories and their respective malaria elimination programmes. These institutions are also part of the steering and scientific committee of the project. Besides the financial or in-kind support from health authorities, the CUREMA project is also funded by the European Funds of Regional Development from PCIA (Programme de Coopération Interreg Amazonie, SYNERGIE 7128 and 8754).

The project received ethical clearance from the Ministry of Health of Suriname (CMWO 005/22), the Fiocruz ethics committee (CEP 5.210.165) and the National ethical committee for health research of Brazil (CONEP 5.507.241). It also complies with the European Regulation on Data Protection. A Data and Safety Monitoring Board (DSMB) has been established to provide external monitoring of the study, specifically advising the investigators and the sponsor about potential safety concerns. Field implementation of the study started in the last quarter of 2022 and is planned to take 27 months (Fig. 5 ). Results will be available at the end of 2025.

The CUREMA project aims at evaluating a complex intervention [ 70 , 71 ]: several components make up the CUREMA intervention per se, including pharmacological intervention and health education activities; the context of the intervention is complex, being cross-border, characterized by challenging operational and logistical aspects due to the Amazonian environment and the fragility of infrastructures, by the interaction of numerous actors belonging to a multicultural and multisector context; the implementation of the intervention and its effectiveness can be significantly influenced by the epidemiological, migratory, political, economic and climatic context of the region. In this context, the authors' objectives cannot be limited to a simple evaluation of effectiveness, but it is fundamental to address the question of for whom, when, why and how this intervention can be effective and relevant [ 70 ].

In terms of intervention’s environment, the CUREMA project is the natural continuation of the Malakit project, which was carried out between 2018 and 2020 by the same nexus of scientific, operational and institutional partners, and whose experience CUREMA capitalizes on. Both projects were born from a virtuous dynamic in which these players, belonging to different professional backgrounds and the three countries in the Region, sought to collectively build creative solutions to common challenges. The reduction in the level of malaria transmission in the three territories is an important contextual element. On the one hand, the participation of Suriname and French Guiana in the E-2025 initiative, as well as the Brazilian government’s commitment to eliminating malaria transmission in the Amazon by 2035, are levers of increased political support to implement ambitious interventions to achieve these goals. On the other hand, paradoxically, the decreasing number of malaria cases may lead to a gradual demotivation of the community and of field professionals involved, whose reduced level of commitment may jeopardize the ability of these interventions to produce the expected effects. The evaluation of the CUREMA project will need to take these contextual factors into account, in order to understand the factors at play in the implementation of the project and its acceptance.

The CUREMA project and the previous MALAKIT project have been conceived with two core principles in mind. The first is medical neutrality and impartiality, i.e. the fact that access to health should be universal, a key principle of medical ethics and humanitarian law [ 72 , 73 ]. The study population has de facto restricted access to healthcare due to its clandestine status, and the aim of the project’s approach is to restore this access, at least in the fight against malaria. Secondly, the “harm reduction” perspective, which involves a non-judgemental approach to promoting health and reducing the harmful effects of a not easily avoidable exposure [ 74 ]. In this case, the exposure is represented by the activity of gold mining, which has very complex social and economic determinants, and on which the health sector is unable to intervene. Precautions must be taken when working in this context. As mentioned above, project’s actions are carried out in neutral contexts, where participants are not in conditions of illegality at the time of inclusion. It is also important to note that these places are widely known in literature and by the authorities [ 36 ], and not revealed by the project. Additionally, data collection carefully avoids gathering information on possible criminal activities (including human trafficking, violence, drug trafficking). Finally, it is important to emphasize that the majority of the study population, although in irregular migratory conditions and involved in unauthorized mineral exploitation, are simple “workers” who are not involved in criminal activities [ 36 ]. They also suffer from very vulnerable socio-economic and health conditions [ 38 , 75 ].

The project team has gradually built up a relationship of trust with the ASGM communities [ 76 ]. Participation in the study by this “hidden” population is facilitated by the fact that the intervention is carried out in “neutral” locations, through work with members of the community, and by the history of collaboration and trust established by the research team and field partners over more than a decade. This has helped to nurture a community-engagement approach with a dual objective: to produce services and results considered relevant by the target community, and to strengthen its involvement and awareness around malaria elimination efforts. The CUREMA project intervention and evaluation components have been designed by researchers and malaria experts, but the opinion of the target population was sought throughout the development process, and most project tools (questionnaires, application, educational material) were developed with their direct participation. In this regard, the participation of the community is situated, on the continuum described by Sanderson and colleagues, between consultation and cooperation [ 77 ]. Nevertheless, the fact that the project proposal is not generated per se by a community approach, could have the effect that the community does not feel it is relevant and does not embrace it, despite efforts to improve their participation.

Interventional health studies can be qualified according to their characteristics on a continuum between the attributes explanatory and pragmatic [ 78 ]. In explanatory trials the object of evaluation is the drug (or technology) per se, which is compared to placebo or standard of care under ‘‘optimal’’ and balanced conditions, in order to identify its specific role in the evolution of a health state. In pragmatic trials, the intervention is evaluated under conditions as close to real life as possible, in order to generate information about its effective applicability [ 78 ]. The drugs used in the study have already been the subject of explanatory studies, or even are already included in national recommendations for the treatment of acute malaria episodes. The CUREMA project proposes an approach that changes the indications or modalities of such treatments, as well as the mode of recruitment of patients receiving the drugs. However, it did not seem relevant to carry out an explanatory study for this approach, and on the contrary, a pragmatic design seems more interesting: due to the nature of the intervention, its applicability in real conditions is indispensable, and a result obtained in controlled ‘‘optimal’’ conditions would not have any added value in terms of decision support for the health authorities. For example, a study recruiting patients in a health facility by medical or paramedical professionals (rarely available in the target locations), with an ‘‘ideal’’ in person clinical and biological follow-up (which does not take into account the high mobility of the target population), would not only make this intervention difficult to transpose to the reality of places with residual transmission in endemic countries, but would also end up missing the very target of the intervention. Field health workers with a similar profile are in charge of treating malaria and other communicable diseases on a daily basis in many countries of the world (including Brazil and Suriname) [ 79 , 80 , 81 , 82 , 83 ]. In Suriname, a partnership with the National Malaria Programme allow to hire as collaborators of the project the same CHWs involved in the programme’s activities. However, setting up an intervention in a research project is by its very nature different from scaling it up in a healthcare system, in terms of organization, administrative, political and logistical constraints, and funding capacity [ 84 ]. These limitations will need to be taken into account when assessing the transferability of the intervention.

The effectiveness evaluation the authors are interested in measuring is the impact of the intervention on malaria transmission at a population level. Field conditions (limited number of inclusion sites, high mobility of the target population across the region between different gold mining areas) would not allow the implementation of a cluster randomized trial, as well as of other types of controlled designs. Effectiveness evaluation with a non-randomized design without a control group will require caution when interpreting the main outcome results. Potential confounding factors must be considered in the interpretation of the results, as changes in malaria prevalence could be linked to external factors such as changes in mobility patterns, environmental variations, or evolutions in malaria control programme activities. Contextual data on the epidemiological, health, environmental, economic and political context will provide additional insight.

Evaluation of implementation (using quantitative and qualitative data) will also allow to interpret the results of the impact assessment more adequately: to what extent was the intervention implemented satisfactorily, and what are the factors favouring or hindering its implementation in general and on specific aspects. The triangulation of these elements will help to understand whether, how and why the intervention worked in the study’s context. This will also provide a basis for imagining whether and how it might work in similar contexts.

Another very important point that will be analysed with CUREMA is the risk–benefit balance (real and perceived) of this targeted drug administration against P. vivax silent carriage. On the one hand, mass drug administration (MDA) aiming at eliminating P. vivax has already been carried out in the past [ 85 , 86 ]. However, these actions were fraught with a dubious risk–benefit balance because of the high proportion of people unnecessarily treated, especially in contexts of medium–low endemicity. An alternative to MDA would be to carry out targeted treatment of people who are seropositive for P. vivax (serological test-and-treat, seroTaT), serology being used as a proxy for recent infection with P. vivax and of the carriage of hypnozoites. This has been used in the past for malaria elimination in southern Brazil, and has been advocated as a mass strategy more recently in several modelling papers [ 66 , 87 ]. However, the unavailability of rapid serological tests that can be used in the field implies that this strategy is not currently applicable to such an isolated and highly mobile population. The proposal for a targeted drug administration strategy based on epidemiological criteria (recent individual history compatible with asymptomatic carriage) is an innovative compromise aimed at improving the risk–benefit balance using simple methods available everywhere and with low cost. The epidemiological criteria used in the study will be compared with serology retrospectively to assess their performance.

The risk of error in the delivery of radical cure intervention by community health workers will be assessed, particularly the risk of delivering 8-aminoquinoline to persons with contra-indications such as G6PD deficiency. To prevent this risk, a comprehensive initial training program [ 59 ] has been set up, as well as periodic supervision and refresher trainings to guarantee the quality of the test performance. The choice of whether to deliver the radical treatment is accompanied by the electronic inclusion form, which provides recommendations in relation to the level of G6PD and other contraindications explored. Although project’s field workers are not professionals with specific training in laboratory techniques, other experiences in Brazil shows that field performance of this test by community health workers without formal qualifications is possible and safe [ 54 , 55 ]. An unpublished study was also carried out in Suriname on the feasibility of testing by community health workers in the malaria programme (the same ones recruited for CUREMA), with satisfactory results (personal communication with Dr. S. Vreden). The frequency and severity of adverse events recorded during the participants’ follow-up will assess the risk incurred by participants. The balance as perceived by participants will be evaluated during qualitative surveys carried out after the intervention. All these elements will thus contribute to the analysis of the risk–benefit balance of this service offered under field conditions, in low to moderate malaria transmission settings to asymptomatic persons.

The CUREMA study will provide an evaluation of a new intervention for hard-to-reach populations, who represent the main challenge for countries approaching the elimination of malaria. These results will, therefore, be disseminated and used to inspire solutions in similar realities, for example in Latin America and Asia [ 13 , 16 , 24 , 28 , 37 ], in the context of transfer to health systems or of further scientific evaluation (including consolidation of the effectiveness results, or medico-economic assessment). Furthermore, the same intervention could also be considered for the management of epidemic phenomena when logistical, political and/or administrative constraints make it impossible to set up on-site interventions (including clandestine populations, war contexts). These results would, therefore, prove extremely valuable to face the challenges of malaria elimination in a growing number of countries [ 88 ].

Data availability

Not applicable.

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Acknowledgements

We would like to thank all the members of the study population who contributed to the development of this project.

The CUREMA study has been funded by the European Funds for Regional Development (Programme de Coopération Interreg Amazonie, SYNERGIE 7128 and 8754) and the Regional Health Agency of French Guiana.

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Alice Sanna, Yann Lambert, Irene Jimeno Maroto, Muriel Suzanne Galindo, Lorraine Plessis, Teddy Bardon, Carlotta Carboni & Maylis Douine

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AS, YL and MD led the methodological reflexion, all the authors took part in it. AS drafted the manuscript. YL elaborated Fig. 1 , AS elaborated the other figures and tables. All the authors read, corrected, and approved the final manuscript.

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Sanna, A., Lambert, Y., Jimeno Maroto, I. et al. CUREMA project: a further step towards malaria elimination among hard-to-reach and mobile populations. Malar J 23 , 271 (2024). https://doi.org/10.1186/s12936-024-05040-8

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A simple Google search located the equation that Dr. Franklin had referred to: dN dt = rN(1 − N K) (Case Study.1) (Case Study.1) d N d t = r N (1 − N K) Where (dN/dt d N / d t) is the rate of increase of the population and N N is the population size, r is the intrinsic rate of increase. K is the carrying capacity of its local environmental ...
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Case Study Questions for Class 12 Biology Chapter 13 Organisms and Populations. Question 1: Organism P has thick lips and tongue so that it can easily feed on the commonly available spiny plants. Organism Q has thick layer of insulating fat under the skin. It was strong hooves to walk steadily on steep surfaces and lives in burrows during winters.
Population Genetics and Evolution (Biology Case Study)
Description. The main idea of this lesson is to explore how population genetics explains the mechanisms of genetic variation and evolutionary processes through principles like allele frequencies, genetic drift, gene flow, and natural selection, illustrated by case studies ranging from the peppered moth to antibiotic resistance in bacteria.
Case Study Questions Class 12 Biology Organisms and Populations
CBSE Case Study Questions Class 12 Biology Organisms and Populations. Case study 1. What are the key elements that lead to so much variation in the physical and chemical conditions of different habitats? The most important ones are temperature, water, light and soil. We must remember that the physico-chemical (abiotic) components alone do not ...
Balancing Human Need & Conservation
Revision Notes. BiologyFirst Exams 2025HL. Topic Questions. Revision Notes. Chemistry. ChemistryLast Exams 2024SL. Topic Questions. Revision Notes. Revision notes on 6.6.6 Balancing Human Need & Conservation for the OCR A Level Biology syllabus, written by the Biology experts at Save My Exams.
Case study in population biology. Sequences and series, find general
At time t=-1 the whole population is fixed for allele H (N(NH,H,-1) = 0) by definition. At time t=0, a mutation had occured and one allele in the population is NH N(NH, H, 0) = 1 by definition. At time t=1, the number of copies of allele NH depends on the fecundity of individuals carrying the mutant allele NH .
Case studies in population biology : Free Download, Borrow, and
Case studies in population biology. Publication date 1985 Topics Population biology -- England -- Woodchester Park, Woodchester Park (England) Publisher Manchester ; Dover, N.H., USA : Manchester University Press Collection printdisabled; internetarchivebooks; inlibrary Contributor Internet Archive
CBSE 12th Standard Biology Organisms and Populations Case Study
According to their response, the organisms are grouped into two types. Answer the following questions. (a) Name the group of organisms, which will show pattern A. Give an example. (b) ame the group of organisms, which will show pattern B. Give an example. (c) Define homeostasis. 'The population of a metro city experiences fluctuations in its ...
Biology PhD alum Eliot Miller taps into new data sources to study bird
Miller came to UMSL based on the strength of its tropical biology program and studied under renowned ecologists and ornithologists Bob Ricklefs and Bette Loiselle. ... Biology PhD alum Eliot Miller taps into new data sources to study bird populations and advocate for habitat preservation Sep 9, 2024; UMSL Tritons weekly rewind Sep 9, 2024;
People with dementia may be at higher risk of having suicidal thoughts
People with dementia are more likely to have suicidal thoughts but are not necessarily more likely to attempt or die by suicide than the general population, finds a new study led by UCL researchers.
CUREMA project: a further step towards malaria elimination among hard
In most countries engaged on the last mile towards malaria elimination, residual transmission mainly persists among vulnerable populations represented by isolated and mobile (often cross-border) communities. These populations are sometimes involved in informal or even illegal activities. In regions with Plasmodium vivax transmission, the specific biology of this parasite poses additional ...