PP2 Role of micro organisms

KNOWLEDGE AREA: Diversity, change and continuity TOPIC 1: Biodiversity and Classification of Micro-organisms Role of Micro- organisms

Role of Micro-organisms in Maintaining Balance in the Environment and Web of Life. Symbiotic Relationships

Some micro-organisms are autotrophic. They are therefore known as producers. As producers they use light energy or chemical energy to make their own food. When the consumers feed on the producer the energy is then transferred to the consumer. This process is known as energy flow.

Look at the example of the aquatic food chain. The phytoplankton use the sunlight to make food. This energy is then transferred to the zooplankton when it feeds on the phytoplankton. The energy is the transferred to the small fish when it feed on the zooplankton and so on.

Therefore the energy from the sun is transferred from the producer to all the consumers. The autotrophic micro-organisms that are produces also photosynthesis. They therefore use up carbon dioxide and release oxygen. Therefore they too maintain the carbon dioxide/oxygen balance. Some micro-organisms act as decomposers, they break down dead and decaying matter. For example : the decomposition bacteria and saprophytic fungi and protists.

As these organisms break down dead and decaying matter, they release important nutrients such as water, carbon dioxide and energy in the form of heat back into the environment. These nutrients can then be reused by other organisms. These nutrients are recycled. Some micro-organisms have close relationships with other organisms. These relationships are called symbiotic relationships.

Symbiosis is a close relationship between two organisms of different species that live together in direct contact. There are 3 types of symbiotic relationships. Mutualism Commensalism Parasitism MUTUALISM: is a relationship between 2 organisms in which both these organisms benefit.

COMMENSALISM: is a relationship where 1 organism benefits and the other does not benefit and is not harmed. PARASITISM: is a relationship between 2 organisms where 1 benefits and the other is harmed. Examples of micro-organisms in these types of relationships: the nitrogen fixing bacteria and in humans Escherichia coli.

Plants and animals use nitrogen to make proteins. However plants cannot absorb the nitrogen as it occurs in the atmosphere (as N2). Plants can only absorb nitrogen in a soluble form, as a nitrate. Animals then obtain their nitrogen from the plants they eat. The nitrogen can be converted into a nitrate by a type of bacteria.

This bacteria is called Nitrogen-fixing bacteria. The Nitrogen-fixing bacteria can live freely in the soil. Some of them are found in the root nodules of plants. The nodule bacteria provides the plant with nitrates and the plant provides the bacteria with manufactured food.

Explain why the relationship between the nodule bacteria and the plant is an example of mutualism.

The plant provides the bacteria with food in the form of carbohydrates, while the bacteria converts nitrogen into nitrates, which the plant can absorb. This is an example of mutualism because the bacteria benefits by obtaining food and the plant benefits by getting nitrates. Since they both benefit this is a mutualistic relationship.

E. coli is one of the many bacteria found in the human intestine. They obtain digested food from the human intestine while the human benefits because they help in the decay of indigestible food and they help to make vitamins B, E and K. This is an example of a mutualism because both the E.coli and the human benefits from this relationship.

Energy flow: is the transfer of energy from one organism to the next. Symbiosis: is a close relationship between two organisms of different species that live together in direct contact. Mutualism: is a relationship between 2 organisms in which both these organisms benefit. Commensalism: is a relationship where 1 organism benefits and the other does not benefit and is not harmed. Parasitism: is a relationship between 2 organisms where 1 benefits and the other is harmed.

The transfer of energy form one organism to the next is known as… A. Energy flow B. Parasitism C. Mutualism D. Commensalism

The relationship between the root nodule bacteria and the plant is an example of… A. Energy flow B. Parasitism C. Mutualism D. Commensalism

The saprophytic fungi… A. Breaks down dead and decaying matter. B. Provides all other organisms in the food chain with oxygen. C. Provides all other organisms in the food chain with nutrients. D. Both A and C.

Saprophytic bacteria play an important role in … A. Nutrient recycling B. Converting nitrogen into nitrate C. Converting nitrate into nitrogen. D. None of the above

Bacteria are important to humans because… A. In the intestine they make certain vitamins. B. They are involved in the decay of indigestible material. C. Both A and B D. None of the above

Plants can only absorb nitrogen in a soluble form as… A. Nitrogen gas B. nitrate C. Both A and B D. None of the above

Autotrophic micro-organisms maintain the ________ balance A. Carbon dioxide/nitrogen B. Oxygen/nitrogen C. Carbon dioxide/oxygen D. None of the above

Autotrophic micro-organisms are also known as … A. producers B. consumers C. decomposers D. None of the above

Heterotrophic organisms obtain their food from… A. photosynthesis B. decomposers C. producers D. None of the above

Prokaryotic organisms lack … A. proteins B. a true nucleus C. mitochondria D. None of the above

1. A 2. C 3. A 4. A 5. C 6. B 7. C 8. A 9. C 10. B