Q41
If by radiation all nitrogenase enzymes are inactivated, then there will be no
Correct Answer
Option A
Solution
(a) Nitrogenase catalyzes biological nitrogen fixation (N2 → NH3) in legume nodules.
Ecosystem
Q42
Which one of the following is not a gaseous biogeochemical cycle in ecosystem?
Correct Answer
Option B
Solution
(b) Phosphorus cycle is sedimentary (no gaseous phase); N, C, S cycles have gaseous phases.
Q43
Pick up the correct food chain
Correct Answer
Option C
Solution
(c) Phytoplankton → Zooplankton → Fish is a correct grazing food chain in aquatic ecosystem.
Q44
In grass-deer-tiger food chain, grass biomass is one tonne. The tiger biomass shall be
Correct Answer
Option B
Solution
(b) 1 tonne grass → 100 kg deer (10%) → 10 kg tiger (10%).
Q45
The pyramid which cannot be inverted in a stable ecosystem is that of
Correct Answer
Option C
Solution
(c) Pyramid of energy is always upright due to unidirectional energy flow and 10% law.
Q46
In a biotic community, the primary consumers are
Correct Answer
Option D
Solution
(d) Herbivores directly consume producers → primary consumers.
Q47
The primary succession refers to the development of communities on a
Correct Answer
Option D
Solution
(d) Primary succession: colonization of a completely new, bare, unoccupied habitat.
Q48
In a food chain, the largest population is that of
Correct Answer
Option B
Solution
(b) Producers form the base of the food chain and are always most abundant.
Q49
Bamboo plant is growing in a fir forest. What will be the trophic level of it?
Correct Answer
Option A
Solution
(a) Bamboo is a plant (producer) → first trophic level.
Q50
An ecosystem which can be easily damaged but can recover after some time if damaging effect stops will be having
Correct Answer
Option A
Solution
(a) Low stability = easily damaged; high resilience = ability to recover quickly.
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