essay on the importance of diffusion in organisms

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Importance of diffusion to living organisms

Diffusion is basically the movement of chemical species (ions or molecules) under the influence of concentration difference. The species will move from the high concentration area to the low concentration area till the concentration is consistent in the whole system. Diffusion mostly occurs in gases and liquids as these can move freely.

The main features of an efficient diffusion system would be that it has a large surface area, thin membrane and a continuous supply of substances. A large surface area is needed so that high amount of substances can be exchanged at a time while the thin membrane means that the diffusion pathway would be short so that it is more efficient. The continuous supply would help in maintaining a concentration gradient which is essential for diffusion to take place.

The 2 main types of diffusion are simple and facilitated. Simple diffusion is when a small, non-polar molecule passes through a lipid bilayer. In this type of diffusion, a hydrophobic molecule moved into the hydrophobic region of the membrane without getting rejected. A key feature is that it does not  need a carrier protein to take place. An example of simple diffusion is osmosis.

Facilitated diffusion on the other hand is dependant on carrier proteins to transport it across the membrane.

Diffusion is essential for many organisms as it is a feature of a number of processes which control and supply vital substances to the body in order for basic survival. A few of these are discussed below.

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Gas exchange is one of these processes. It is when much needed oxygen is obtained by the body in order for respiration to take place and the waste CO 2  is taken out of the body. In us mammals, the exchange takes place in the lungs which contain a large number of alveoli. These are sponge-like structures in which the diffusion takes place. They are highly adapted to diffuse the gases as they give a large surface area for exchange of the gases. Also, there is only a thin layer of cells between the alveoli and the blood capillaries meaning there is a short diffusion pathway so diffusion takes place more efficiently. There is a ventilation system which means there is continuous oxygen supply to the alveoli which again makes diffusion more efficient.

Fish are adapted to exchange gases as the gills have many lamellae which are covered with plates. These give a large surface area while also they are very thin to give a short diffusion pathway. There is a counter flow blood system meaning it flows in the opposite direction of the water. This maintains a concentration gradient in order for diffusion to take place.

The main feature of the mechanism in insects is that they have an extensive tracheole system that gives a large surface area. These are permeable to CO 2 and O 2  in order to allow the exchange of gases.

Plants require CO 2  for the purpose of photosynthesis. Therefore they have thin cell walls and membranes to allow gases to diffuse through. There are stomata which control the entry and exit of gases while there are large air spaces for circulation so that diffusion is efficient.

The transport of glucose to cells is by facilitated diffusion and this is needed as all cells need to respire therefore glucose is vital.

Diffusion also plays a part in the human digestive system as after the carbohydrates and other substances are processed through digestion, the substances that are wanted and are small enough are reabsorbed through the gut wall through diffusion. These can then be used for energy and growth purposes.

The process of osmosis (or osmoregulation) is classed as a type of diffusion. This is due to the fact that the substance (which is water in the case of osmosis) moves from an area of high concentration to an area with lower concentration.

One example of when osmosis takes place is when water is taken up by the roots of plants. Firstly, the water enters the root hair from an area of high water potential. As the water builds up in the cell, it has a higher potential than that of the next cell up, meaning that once again the water moves to the next cell by osmosis. This process carries on transporting the water up through the roots. The system of the roots is called the symplast pathway.

An instance of osmosis in mammals is the reabsorption of water from the kidney tubules back into the blood. A function of the kidney is to control the water level in the blood. The water is absorbed in the descending limb of the loop of henle. This is the part which is permeable to water. The water potential in the descending limb is higher than in the surrounding tissues meaning that water diffuses through into the tissues by osmosis. This is vital for mammals as it controls water loss to a degree by keeping it to a minimum (although water is lost by other means such as perspiration).

The occurrences of diffusion discussed above give us a basic insight into the importance of diffusion in organisms. The majority of living organisms require diffusion to take place in order for main systems to function. These key systems such as gaseous exchange and water control would be unable to function without diffusion taking place. . Without diffusion there would be no respiration of the cells which is the central process in all the biological systems, thus we can say safely state that it is probably the most important process for organisms as without it, there would be no chance of survival whatsoever.

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*** This piece of writing discusses diffusion in the right way with a good range of relevant examples. However, it does not gain a higher star rating because of a lack of detail. Examiners want to see evidence that candidates have learned new content at AS and A level and that they can use A level terminology correctly and in the right context. If particular terms are used it is important that a candidate shows that they really understand what those terms mean.

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• Cell (Biology): An Overview of Prokaryotic & Eukaryotic Cells

Why Is Diffusion Important to the Life of a Cell?

3 Properties of a Cell

A cell's surrounding plasma membrane acts as a barrier to most molecules, especially those that are dangerous to the life of the cell. The membrane allows passage of beneficial materials by the process of diffusion. The evolution of cellular diffusion allows cells to cordon themselves off from and differentially interact with their immediate environment.

In order to conduct the day-to-day activities of daily life, all cells must transfer essential ions and small molecules across semi-permeable plasma membranes. Ions are atoms or molecules with a net positive or negative charge. To fulfill the requirements of life, cells exchange gases, such as oxygen and carbon dioxide; excrete waste products; and take in particles of food, water and minerals. The exchange takes place between the inner cell and its surrounding extra-cellular fluid.

Cellular Membranes

Living cells have evolved a membrane to fence off and contain its inner organic chemicals, while selectively allowing only essential atoms and simple compounds to cross back and forth. According to the standard lipid bilayer model, the fatty-acids called phospholipids and glycolipids are the main components of cellular membranes. Other elements of the membranes are cholesterol, proteins and carbohydrates. The lipid bilayer is impermeable to most cations, or negative ions, and anions, or positive ions.

Diffusion is a process where molecules and ions move naturally from an intracellular region of high concentration to an area of lower concentration, or vice versa. Diffusion occurs spontaneously without the expenditure of energy by the cell in a procedure known as passive transport. The molecules migrate across the cellular concentration gradient until a state of equilibrium is reached. Osmosis is a type of diffusion involving the passage of water into and out of the cell.

Active Transport

Cells expend energy to actively transport molecules against the relative concentration gradient. Active transport, or facilitated diffusion, forces ions and molecules through the cell's membrane. The nucleotide adenosine triphosphate, or ATP, is the cell's standard energy currency enabling the process. Nucleotides are a type of nucleic acid. Large, complex, non-lipid soluble molecules, such as glucose sugars and proteins, are moved by active transport systems. The systems maintain osmotic balance and prevent the cell from exploding by taking in too much water.

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• Biology Article

Table of Contents

What is Diffusion?

Types of diffusion, factors affecting diffusion, examples of diffusion, causes of diffusion, significance of diffusion, diffusion definition.

“Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration down the concentration gradient.”

Read on to explore what is diffusion and the different types of diffusion.

Diffusion is the process of movement of molecules under a concentration gradient. It is an important process occurring in all living beings. Diffusion helps in the movement of substances in and out of the cells. The molecules move from a region of higher concentration to a region of lower concentration until the concentration becomes equal throughout.

Liquid and gases undergo diffusion as the molecules are able to move randomly.

Take water in a beaker. Add a few copper sulfate crystals in one place and leave it as it is for some time without disturbing it. After some time we can see that the beaker contains a uniformly coloured solution. Here, both water and copper sulfate diffuse independently. With this experiment, we can infer that solutes move from a higher concentration to a lower concentration in a solution.

Also Read:  Diffusion in Plants

Recommended Video:

Diffusion is widely used in various fields such as biology, physics, chemistry, etc. Diffusion can be classified into two main types: Simple diffusion and facilitated diffusion.

Simple diffusion

A process in which the substance moves through a semipermeable membrane or in a solution without any help from transport proteins.  For example, bacteria deliver small nutrients, water and oxygen into the cytoplasm through simple diffusion.

Facilitated diffusion

Facilitated diffusion is a passive movement of molecules across the cell membrane from the region of higher concentration to the region of lower concentration by means of a carrier molecule.

Dialysis:  It is the diffusion of solutes across a selectively permeable membrane. A selectively permeable membrane is one that allows only specific ions and molecules to pass through, while it obstructs the movement of others.

Osmosis:  It is the movement of solvent molecules from the region of lower concentration to the region of higher concentration through a semipermeable membrane.    Since water is solvent in every living being, biologists define osmosis as the diffusion of water across a selectively permeable membrane. For example, plants take water and minerals from roots with the help of osmosis.

Also Read:  Facilitated Diffusion

There are a few factors that affect the process of diffusion, which individually and collectively alters the rate and extent of diffusion. These factors include:

• Temperature.
• Area of Interaction.
• Size of the Particle.
• The steepness of the concentration gradient.
• A tea bag immersed in a cup of hot water will diffuse into the water and change its colour.
• A spray of perfume or room freshener will get diffused into the air by which we can sense the odour.
• Sugar gets dissolved evenly and sweetens the water without having to stir it.
• As we light the incense stick, its smoke gets diffused into the air and spreads throughout the room.
• By adding boiling water to the dried noodles, the water diffuses causing rehydration and making dried noodles plumper and saturated.

Diffusion is a natural and physical process, which happens on its own, without stirring or shaking the solutions. Liquid and gases undergo diffusion as the molecules are able to move randomly. The molecules collide with each other and change their direction.

Diffusion is an important process, which is involved in the different life processes . As mentioned above, it is the net movement of particles, ions, molecules, solution, etc. In all living species, diffusion plays an important role in the movement of the molecules during the metabolic process in the cells.

Diffusion is important for the following reasons:

• During the process of respiration, this process helps in diffusing the carbon dioxide gas out through the cell membrane into the blood.
• Diffusion also occurs in plant cells. In all green plants, water present in the soil diffuses into plants through their root hair cells.
• The movement of ions across the neurons that generates electrical charge is due to diffusion.

Also Read:  Difference between diffusion and osmosis

Frequently Asked Questions

1. what is diffusion.

Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration down the concentration gradient.

2. List the types of diffusion.

Diffusion can be divided into two main types, namely, simple diffusion and facilitated diffusion.

3. What is simple diffusion?

Simple diffusion is defined as the process in which a substance moves through a semipermeable membrane or in a solution without any help from transport proteins.

4. State an example of simple diffusion.

In a cell, water, oxygen and carbon dioxide molecules can pass directly through the cell membrane without requiring any energy along the concentration gradient. This is a form of simple diffusion.

5. What is facilitated diffusion?

Facilitated diffusion can be defined as the passive movement of molecules across the cell membrane from a region of higher concentration to a region of lower concentration by means of a carrier molecule.

6. Provide an example of facilitated diffusion.

In the human body, glucose molecules, sodium and potassium ions use carrier proteins to pass through the cell membranes.

7. How does dialysis work?

Dialysis works through the diffusion of solutes across a selectively permeable membrane. A selectively permeable membrane is the one that allows only specific ions and molecules to pass through while obstructing the movement of other molecules.

8. What are the factors affecting diffusion?

Temperature, area of interaction, size of the particle and the steepness of the concentration gradient are all factors that affect the process of diffusion.

9. State the significance of diffusion.

Diffusion is a very important process occurring in all living beings. All living organisms exhibit one or the other form of diffusion, allowing the movement of the molecules during various metabolic or cellular processes.

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What is the purpose of diffusion?

Diffusion is the way of passive transport of substances in and out of the cell across the cell membrane. Diffusion occurs down the concentration gradient, i.e. from higher concentration to lower concentration.

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The importance of diffusion essay

Subject: Biology

Age range: 16+

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Last updated

24 May 2021

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A-Level biology ’ the importance of diffusion’ essay

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