Question

Which of the following are major functions of an ecosystem?
I. Sustain life systems.
II. Synthesis of inorganic matter by producers.
III. Decomposes dead organic matter back to the ecosystem.
IV. Cycles minerals and nutrients.

• A. I, II & IV
• B. II & III
• C. I, III & IV
• D. I & IV

Answer 1

The correct option is C I, III & IV

Ecosystem is a functional unit of nature where living organisms interact among themselves and with their physical environment. The interactions between biotic and abiotic components in the ecosystem ensures the sustenance of life in it. Hence statement I is correct.

Plants convert light energy (sunlight) to chemical energy through photosynthesis using water, carbon dioxide (inorganic substances) in the presence chlorophyll, to produce glucose (organic substance). Hence statement II is incorrect.

Ecosystem is responsible for the cycling of nutrients. For example, nitrogen is present in the soil. It is absorbed in the form of nitrates or nitrites by plants, and from plants it will become part of the animal body. When plants or animals die the minerals from their body go back to soil. Nitrogen-fixing bacteria in the soil convert it to usable forms of nitrates and nitrites, again to be absorbed by the plants. This cycle continues. Hence statement IV is correct.

Decomposers or detrivores secrete digestive enzymes which digest the organic material present in dead plants and animals. They later absorb a part of the decomposed products for their nourishment. The remaining substances add minerals and nutrients to the soil. Hence. statement III is correct.