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Here is a term paper on the ‘Relationship between Organisms and the Environment’ for class 9, 10, 11 and 12. Find paragraphs, long and short term papers on the ‘Relationship between Organisms and the Environment’ especially written for school and college students.
Organisms and the Environment
Term Paper Contents:
- Term Paper on the Energy Flow among Organisms
- Term Paper on the Food Chains and Food Webs
- Term Paper on the Energy Loss along a Food Chain
- Term Paper on the Pyramids of Numbers, Biomass and Energy
- Term Paper on the Carbon Cycle
- Term Paper on the Nitrogen Cycle
- Term Paper on the Water Cycle
- Term Paper on the Parasitism
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Term Paper # 1. The Energy Flow among Organisms:
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The source of energy for all life on the planet is the sun. Living organisms use that energy for their activities. So long as the sun continues to shine, life can continue.
The heat energy from the sun is used by organisms such as ‘cold-blooded’ animals to keep their bodies warm. The sun also supplies light energy, which is locked away by plants during photosynthesis to form chemical energy in food molecules. A plant’s chemical energy is passed on to an animal when the animal eats the plant. If that animal is eaten by another animal, the energy is passed on again.
In this way, the sun’s energy enters then flows through biological (eco) systems, and is gradually lost to the environment as it passes from one organism to the next. It is never recycled.
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Term Paper # 2. Food Chains and Food Webs:
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Definition of Food Chain:
A Food Chain is a sequence of organisms, starting with a photosynthesising organism (usually a green plant), through which energy is passed as one organism is eaten by the next in the sequence.
An example of a food chain in a large pond:
Note:
Algae are unicellular organisms which contain chlorophyll and photosynthesise.
In any one habitat, such as a pond or mangrove swamp, there will be many organisms living together forming an ecosystem. The food chains involving all of these organisms will be interconnected.
Definition of Food Web:
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A FOOD WEB is made up of interlinked food chains involving organisms within the same ecosystem.
All food chains, and thus all food webs, begin with a photosynthesising organism, the producer. When organisms in a food chain/web die, they are decomposed by saprotrophic organisms – usually bacteria and fungi.
Term Paper # 3. Energy Loss along a Food Chain:
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Some of the energy locked away by producers (plants) is released by the producer itself through the process of respiration. Some of the energy is used by the producer, for example, in the processes of cell division, growth and reproduction. A lot of energy is still present when a plant dies, and is then available to decomposers. Only about 10% of a plant’s available energy is passed on to the herbivores which eat it.
Herbivores then release the energy by respiration, and use it for growth, movement and, as heat, to maintain body temperature.
Much of the energy is still present in the faeces of herbivores, and some in the nitrogenous waste. This is available to decomposers. Not all herbivores are eaten, so the amount of energy available to be passed on to carnivores is small, at around 20%. This is only 2% of the amount that originated in the producer.
The longer the food chain, the less energy available to the carnivore at the end of the chain. Short food chains are therefore much more energy-efficient than long ones. In order to supply enough energy in food to maintain an ever- increasing world population, it must be realised that far less energy is lost when humans eat green plants than when crop plants are fed to animals which are then eaten by humans.
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Term Paper # 4. Pyramids of Numbers, Biomass and Energy:
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Producers (plants) need to produce enough food – and therefore enough energy – for their own metabolic processes. They must also provide enough food for the herbivores that eat them, and leave enough surviving individuals to reproduce the next generation. Therefore, we would expect there to be a larger number of producers than primary consumers (herbivores). For the same reasons, we would expect there to be more primary consumers than secondary consumers, and so on.
These decreasing numbers along a food web can be represented in the form of a pyramid of numbers, as shown below:
However, this representation of feeding relationships can be misleading: one large plant may sustain a large number of very small herbivores; and one carnivore may sustain a large number of smaller carnivores.
If this is the case, we see a ‘top heavy’ pyramid, as shown below:
A pyramid of biomass is a pyramid constructed using the dry mass of organisms at each trophic level in a food chain (or food web). It produces pyramids of a more standard shape (e.g. Fig. 61) and can be constructed by collecting data from population estimates in any particular habitat. Biomass is the total dry mass of a population, i.e. the theoretical mass of chemicals other than water in the organisms under consideration (water can vary considerably).
A pyramid of energy is the most reliable of all the representations of the interactions between organisms in a food web. It shows how much energy is passed from one trophic level to the next, within organisms in a food web, over a period of time. It thus allows for the growth of producers over that period, and thus can show productivity (how much organic material is made) and how much energy is passed on, during that period, to the herbivores.
Its shape is that of a standard pyramid (like the pyramid of biomass), but the information necessary to construct it is difficult to obtain, since it requires knowing how much of all the different foodstuffs are manufactured by the producer, how much energy they contain, and how much of each foodstuff is passed on to each member of the food web.
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Term Paper # 5. The Carbon Cycle:
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When decomposition occurs, carbohydrates in the dead organic matter are used as the substrate for respiration by decomposers (bacteria and fungi). Carbon dioxide is released into the atmosphere, as it is in all cases of aerobic respiration.
Combustion, the burning of fuels, also releases carbon dioxide into the atmosphere. Many of these fuels are fossil fuels such as coal, gas and oil.
Photosynthesis absorbs that carbon dioxide and converts it into carbohydrates (which may then be used to make fats or proteins) in a plant.
Animal nutrition involves the transfer of these carbon-containing molecules to animals. Animals and plants respire, and eventually die and are decomposed, releasing the carbon dioxide back into the atmosphere, and so the cycle continues.
Term Paper # 6. The Nitrogen Cycle:
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Decomposition includes the conversion by bacteria of proteins to amino acids, and the conversion of amino acids and urea to ammonium ions. This process usually takes place in the soil.
Ammonium ions contain nitrogen atoms, but before plants can absorb nitrogen from the soil, it must be in the form of nitrate ions.
Nitrifying bacteria convert ammonium ions first into nitrites then into nitrates.
Plants absorb the nitrates and use them together with the carbohydrates made by photosynthesis, to make amino acids and then proteins.
Animals eat the protein in plants and excrete, e.g. urea. Both plants and animals die, and decomposition releases ammonium ions again.
Atmospheric nitrogen (79% of the air) cannot be used either by plants or by animals in its gaseous form, but it is used by some bacteria (the nitrogen fixing bacteria).
These bacteria are found in two forms:
(i) Those which live in swellings called nodules on the roots of peas, beans and other leguminous plants.
(ii) Those which live freely in the soil.
Nitrogen fixation by these bacteria changes the atmospheric nitrogen, via ammonia, into proteins. The nitrogen becomes available to other organisms when these proteins later decompose.
Nitrogen fixation also occurs when lightning passes through the nitrogen in the air, converting it to nitric acid which forms nitrates in the soil.
Term Paper # 7. The Water Cycle:
Water is a substance essential to life on this planet.
It is important for the following reasons:
i. It is the medium in which all metabolic reactions take place.
ii. Water is sometimes called ‘the universal solvent’.
iii. It is the means of transporting chemicals in plants and animals.
iv. It is used in photosynthesis.
v. It is used in temperature regulation in many animals.
vi. It is given off in transpiration and respiration.
vii. It is a major constituent (about 85%) of all cells.
Like carbon and nitrogen, it is a chemical which is recycled.
Term Paper # 8. Parasitism:
Definition of Parasitism:
A parasite can be defined as an organism which obtains its food from another, usually larger living organism (‘host’); the host always suffering in the relationship.
Pathogens are therefore parasites. One such pathogen is the unicellular organism Plasmodium which causes malaria.
Malaria:
Malaria is a disease caused by a single-celled microorganism called Plasmodium which lives in red blood cells. It is carried from person to person (host to host) by the female Anopheles mosquito. The mosquito is described as the vector, or carrier, of the microorganism. Usually at night, while the host is asleep, she injects her saliva into a (healthy) person before she starts to suck the blood which she needs for her developing eggs.
The saliva contains a chemical to stop the blood from clotting. If the mosquito has previously taken blood from a person infected with malaria, it may also contain the parasite Plasmodium. The parasite is transferred from the blood of one host, where it lives and develops, to the blood of a second host.
Control of Malaria:
Malaria can be controlled in three ways:
A. By controlling the mosquito vector.
B. By avoiding mosquito bites.
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C. By treating the parasite in the blood.
A. Controlling the Mosquito:
(i) Cover water tanks with netting to stop mosquitoes laying their eggs in the water.
(ii) Drain swamps where mosquitoes lay their eggs.
(iii) Introduce fish such as Tilapia into the swamps to feed on mosquito larvae.
(iv) Cover the surface of the water with light oil. Larvae cannot then use the water film from which they hang as they breathe air from the atmosphere. The larvae therefore suffocate.
(v) Use insecticides or mosquito coils to kill or repel adult mosquitoes inside buildings.
B. Avoiding Mosquito Bites:
(i) Place nets over doors and windows.
(ii) Wear clothes which cover wrists and ankles, especially in the evenings, when mosquitoes are most active.
(iii) Use insect repellent sprays.
(iv) Sleep under mosquito nets.
C. Protection against the Parasite Plasmodium:
(i) Take drugs regularly to kill the parasite if it enters the bloodstream. The correct drug (e.g. Paludrin) must be taken for the particular type of Plasmodium.
(ii) Treat patients suffering from malaria with a higher dosage of anti-malarial drug, and isolate them to prevent spreading of the disease.
