Energy flow — NEET Biology Questions

Practice 40 questions on Energy flow from Ecosystem (NCERT Class 12, Chapter 12). Free samples below — get all 40 in the app.

40 Questions Ecosystem Class 12

Sample Questions — Energy flow

Try 5 questions below from Energy flow. Get all 40 in the MedicNEET app.

MCQ
Why does no energy remain trapped indefinitely in any organism?
  • A. Energy gets converted to light
  • B. It is absorbed by other organisms
  • C. It is passed on or lost as heat
  • D. It is stored permanently in ATP
✅ Correct Answer: C
Energy is either transferred to the next trophic level or lost as heat; no energy remains indefinitely in an organism.
MCQ
Assertion (A): Pyramids of energy are always downwards. Reason (R): Energy is lost as heat at every trophic level.
  • A. Both A and R are true, and R is the correct explanation of A
  • B. Both A and R are true, but R is not the correct explanation of A
  • C. A is true, R is false
  • D. A is false, R is true
✅ Correct Answer: D
Pyramids of energy are always upright. The irreversible loss of energy as heat ensures energy decreases at each level, keeping the pyramid upright.
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MCQ
Assertion (A): Only 10% of energy is transferred from one trophic level to the next. Reason (R): A large amount of energy is lost as heat at each trophic level.
  • A. Both A and R are true, and R is the correct explanation of A
  • B. Both A and R are true, but R is not the correct explanation of A
  • C. A is true, R is false
  • D. A is false, R is true
✅ Correct Answer: A
Energy transfer across trophic levels is inefficient due to heat loss, resulting in only 10% energy transfer.
MCQ
Which law of thermodynamics does energy loss as heat in ecosystems follow?
  • A. Second law
  • B. Darwin's law
  • C. First law only
  • D. Boyle’s law
✅ Correct Answer: A
Ecosystems are not exempt from the Second Law of Thermodynamics.
MCQ
Which organisms break down detritus by secreting digestive enzymes?
  • A. Zooplankton
  • B. Saprotrophs
  • C. Herbivores
  • D. Producers
✅ Correct Answer: B
Decomposers, also called saprotrophs, degrade detritus enzymatically.

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