4.3 The Decay Process
Living organisms remove material for, the environment for growth and other purposes. For example, plants take elements like oxygen, carbon, hydrogen and nitrogen from the soil and air. These elements are turned into complex compounds that make up the organism, such as proteins, carbohydrates and fats. These complex molecules (and the elements that they are made out of) pass through the food chain.
When an organism produces a waste product or dies, the elements in the complex molecules are returned to the environment. They are returned back into the environment through a process known as decay. Decay is undertaken by microorganisms known as decomposers and larger organisms called detritivores.
When an organism produces a waste product or dies, the elements in the complex molecules are returned to the environment. They are returned back into the environment through a process known as decay. Decay is undertaken by microorganisms known as decomposers and larger organisms called detritivores.
Saprophytes
When an organism has died, their body usually decay. During decay, carbon is returned to the atmosphere in the form of carbon dioxide through the respiration of the decomposerThe main groups microorganism decomposers are fungi and bacteria. Bacteria and fungi are both single celled organisms. Decomposer break down waste produce from animals and dead animals by releasing enzymes. The enzymes break the complex molecules that are present in the waste produce/ dead material into smaller molecules that can be absorbed by the decomposer. This results in nutrients being available in mineral form in soil, which is available for new plants. The microorganisms that cause decay are known as saprophytes, which simple means a plant, fungus or microorganism that lives on dead or decaying organic matter.
s that are decaying the dead material. Over millions of years, some of the dead materials from animals and plants may become fossil fuels (e.g. oil). These fossil fuels store carbon until they are burnt, which results in the carbon dioxide being returned to the atmosphere in the form of carbon dioxide.
When an organism has died, their body usually decay. During decay, carbon is returned to the atmosphere in the form of carbon dioxide through the respiration of the decomposerThe main groups microorganism decomposers are fungi and bacteria. Bacteria and fungi are both single celled organisms. Decomposer break down waste produce from animals and dead animals by releasing enzymes. The enzymes break the complex molecules that are present in the waste produce/ dead material into smaller molecules that can be absorbed by the decomposer. This results in nutrients being available in mineral form in soil, which is available for new plants. The microorganisms that cause decay are known as saprophytes, which simple means a plant, fungus or microorganism that lives on dead or decaying organic matter.
s that are decaying the dead material. Over millions of years, some of the dead materials from animals and plants may become fossil fuels (e.g. oil). These fossil fuels store carbon until they are burnt, which results in the carbon dioxide being returned to the atmosphere in the form of carbon dioxide.
Detritivores
Larger organisms involved in the decay process are known as detritivores. Examples of detritivores include earthworms, woodlice and maggots. These organisms break waste produce or dead material into small pieces, which increases the surface area available for saprophytes to break down the material.
In a stable ecosystem, the nutrient that are taken out of the soil is replaced by the processes that return materials to the soil. The materials are constantly being recycled.
Larger organisms involved in the decay process are known as detritivores. Examples of detritivores include earthworms, woodlice and maggots. These organisms break waste produce or dead material into small pieces, which increases the surface area available for saprophytes to break down the material.
In a stable ecosystem, the nutrient that are taken out of the soil is replaced by the processes that return materials to the soil. The materials are constantly being recycled.
What Affects the Speed of Decay
There are many factors that affect the speed of decay.
One factor is temperature. Microorganisms release enzymes and the enzymes that they release have an optimal temperature where their rate of reaction is maximised. A temperature above the optimal temperature for the enzymes causes the shape of the enzymes and proteins to change, which causes the rate of reaction to fall and the microorganism to die. A temperature that is too low results in a low reaction rate because there is both less energy to start a reaction and the substances that the enzyme is breaking down have less kinetic energy meaning that less substrates enter the active sites of enzymes (the substrate is the molecules that the enzyme is acting upon and the active site is the part of the enzyme that the substrate fits into). So, the temperature must be warm to increase the rate of reaction but not too warm as this would result in denaturing of the enzyme.
Most decay occurs by organisms that require oxygen. However, some microorganism can decay material in the absence of oxygen.
Aerobic decomposition refers to microorganisms that require oxygen to decompose martial. Oxygen is needed for decay because the microorganisms need to respire in order to survive. If there is a lack of oxygen then it would result in the microorganism dying and therefore the rate of decay will fall because there are fewer microorganisms to decay the material.
However, some microorganisms are able to survive without oxygen. Decomposition by these microorganisms is known anaerobic decomposition. But most microorganisms involved in decay require oxygen and will die without oxygen in sufficient quantities. A way to remember the difference between aerobic and anaerobic decomposition is to relate it to aerobic and anaerobic respiration. Aerobic respiration is respiration with oxygen and anaerobic respiration is respiration without oxygen.
The final factor that we will look at that affects the rate of decay is the quantity of water. A lack of water will slow the rate of decay because water is needed to transport substances and facilitate reactions inside a microorganism. However, too much water can result in the reduce the amount of oxygen that the microorganism has access to, which results in the microorganism potentially dying.
There are many factors that affect the speed of decay.
One factor is temperature. Microorganisms release enzymes and the enzymes that they release have an optimal temperature where their rate of reaction is maximised. A temperature above the optimal temperature for the enzymes causes the shape of the enzymes and proteins to change, which causes the rate of reaction to fall and the microorganism to die. A temperature that is too low results in a low reaction rate because there is both less energy to start a reaction and the substances that the enzyme is breaking down have less kinetic energy meaning that less substrates enter the active sites of enzymes (the substrate is the molecules that the enzyme is acting upon and the active site is the part of the enzyme that the substrate fits into). So, the temperature must be warm to increase the rate of reaction but not too warm as this would result in denaturing of the enzyme.
Most decay occurs by organisms that require oxygen. However, some microorganism can decay material in the absence of oxygen.
Aerobic decomposition refers to microorganisms that require oxygen to decompose martial. Oxygen is needed for decay because the microorganisms need to respire in order to survive. If there is a lack of oxygen then it would result in the microorganism dying and therefore the rate of decay will fall because there are fewer microorganisms to decay the material.
However, some microorganisms are able to survive without oxygen. Decomposition by these microorganisms is known anaerobic decomposition. But most microorganisms involved in decay require oxygen and will die without oxygen in sufficient quantities. A way to remember the difference between aerobic and anaerobic decomposition is to relate it to aerobic and anaerobic respiration. Aerobic respiration is respiration with oxygen and anaerobic respiration is respiration without oxygen.
The final factor that we will look at that affects the rate of decay is the quantity of water. A lack of water will slow the rate of decay because water is needed to transport substances and facilitate reactions inside a microorganism. However, too much water can result in the reduce the amount of oxygen that the microorganism has access to, which results in the microorganism potentially dying.
A Compost Bin
Compost bins take food and plant waste and turns it into compost that is spread on crops (usually in someone’s garden or allotment). The compost that is produced from the dead and waste material that is placed into a compost bin is very high in nutrients. This is why when it is spread across crops, the yields of the crops increase because the crops are able to take in all of the nutrients that they require for growth (this is the case providing the plants other demands have been met sufficiently e.g. it has had access to enough sun light, water etc.).
Compost bins are designed to increase the rate of decay. Compost bins are usually dark colours. This is because dark colours tend to absorb more infrared radiation compared with light colours, which results in compost bins being warm. Warmer conditions result in a greater rate of decay (providing that the temperature does not become too hot, which may cause the enzymes to denature). Some compost bins have air holes, which allows oxygen to enter the compost bin in sufficient quantities to cause the rate of decay to increase. Compost bins must also be moist but not too wet because water is needed for the decay process.
Compost bins take food and plant waste and turns it into compost that is spread on crops (usually in someone’s garden or allotment). The compost that is produced from the dead and waste material that is placed into a compost bin is very high in nutrients. This is why when it is spread across crops, the yields of the crops increase because the crops are able to take in all of the nutrients that they require for growth (this is the case providing the plants other demands have been met sufficiently e.g. it has had access to enough sun light, water etc.).
Compost bins are designed to increase the rate of decay. Compost bins are usually dark colours. This is because dark colours tend to absorb more infrared radiation compared with light colours, which results in compost bins being warm. Warmer conditions result in a greater rate of decay (providing that the temperature does not become too hot, which may cause the enzymes to denature). Some compost bins have air holes, which allows oxygen to enter the compost bin in sufficient quantities to cause the rate of decay to increase. Compost bins must also be moist but not too wet because water is needed for the decay process.