Our Environment Practice
Solve chapter-level practice questions for Our Environment with reveal-only solutions and quick revision support.
Practice Set 1 — Ecosystem and Energy Flow
Components of an ecosystem, food chains, and the 10% law.
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Practice Set 2 — Human Impact on the Environment
Biodegradable waste, biological magnification, and ozone depletion.
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Quick Q&A Before You Revise
Why is the flow of energy in an ecosystem said to be unidirectional?
Energy captured by producers moves to herbivores, then to carnivores, and is finally lost as heat. It does not flow back from consumers to producers or from the Earth to the Sun, so it moves only in one direction.
What will happen if we kill all the organisms in one trophic level?
The organisms in the next higher level will lose their food and decline, while the level below will increase because nothing is eating it. The whole ecosystem is disturbed, though a rich food web can partly absorb the shock.
Why are some substances biodegradable and some non-biodegradable?
Biodegradable substances have chemical bonds that the enzymes of decomposer bacteria and fungi can break. Non-biodegradable substances (like many plastics) have bonds that these enzymes cannot act on, so they are not broken down naturally.
Will the impact of removing all the decomposers be equally harmful for an ecosystem as the removal of all the producers?
Both are extremely harmful. Without producers there is no food or energy input. Without decomposers, dead matter piles up and nutrients are not recycled, so producers eventually run out of raw materials. The ecosystem collapses in either case.