Biology · chapter PYQs
Ecosystem, on the exam screen.
7 questions from NEET 2026, Re-NEET 2026, NEET 2020, 7 minutes, marked +4 / −1. See them with solutions.
Ecosystem · PYQs
Candidate: You
Time Left
Q1/7
Match List-I with List-II and choose the correct answer from the options given below:
List I
List II
P) Productivity
I) Gross primary productivity minus respiration losses
Q) Net primary productivity
II) Rate of formation of new organic matter by consumers
R) Gross primary productivity
III) Rate of biomass production
S) Secondary productivity
IV) Rate of production of organic matter during photosynthesis
Answer and explanation
Answer: (1)
Productivity is the rate of biomass production ; net primary productivity equals gross primary productivity minus respiration losses ; gross primary productivity is the rate of organic matter production during photosynthesis ; and secondary productivity is the rate of formation of new organic matter by consumers . This matches P-III, Q-I, R-IV, S-II.
Match List-I with List-II and choose the correct answer from the options given below:
List I
List II
P) Decomposition
I) Accumulation of dark coloured amorphous colloidal substance
Q) Detritus
II) Release of inorganic nutrients by the activity of microbes in soil
R) Mineralisation
III) Breaking down of complex organic matter into inorganic substances.
S) Humification
IV) Dead remains of plants and animals including fecal matter
Answer and explanation
Answer: (2)
Decomposition is the breaking down of complex organic matter into inorganic substances; detritus is the dead remains of plants and animals including faecal matter; mineralisation is the release of inorganic nutrients by microbial activity in soil; and humification is the accumulation of the dark-coloured amorphous colloidal humus. This gives P-III, Q-IV, R-II, S-I.
Ecological pyramids represent the relationship between the organisms at different trophic levels and they are generally inverted for:
Answer and explanation
Answer: (4)
Pyramids of number and biomass in grassland are upright, and the pyramid of energy is always upright. Inversion typically occurs for the pyramid of biomass in a sea/aquatic ecosystem, because the standing biomass of the phytoplankton (producers) at any moment is smaller than that of the zooplankton and consumers they support. Hence the pyramid of biomass in sea is inverted.
Which of the following are primary consumers in a food chain?
Answer and explanation
Answer: (3)
Primary consumers occupy the second trophic level and feed directly on the producers, which makes them by definition the herbivores. Carnivores that eat herbivores are secondary consumers at the third trophic level, and those that eat secondary consumers are tertiary. NCERT Class 12, Ecosystem.
Which of the following statements are Correct ?
Statement I: Energy flow from producers to consumers is unidirectional
Statement II: Energy pyramid can never be inverted
Statement III: Transfer of energy follows the 1% law
Choose the correct answer from the options given below :Answer and explanation
Answer: (2)
Energy enters an ecosystem as sunlight and moves in one direction only, from producers to successive consumer levels, being lost as heat at each step - it is never recycled the way nutrients are, so (Statement I) is correct. Because of that unavoidable loss, each level holds less energy than the one below it, so the pyramid of energy is ALWAYS upright and can never be inverted, making (Statement II) correct. Statement III misquotes Lindeman's rule, which is the 10 PER CENT law, not 1 per cent. NCERT Class 12, Ecosystem.
In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct?
Answer and explanation
Answer: (1)
Gross primary productivity (GPP) is the total amount of energy fixed by photosynthesis, while net primary productivity (NPP) is GPP minus the energy used by plants for respiration. Therefore, GPP is always more than NPP. Chapter: Ecosystem.
Match the trophic levels with their correct species examples in a grassland ecosystem.
List I
List II
P) Fourth trophic level
I) Crow
Q) Second trophic level
II) Vulture
R) First trophic level
III) Rabbit
S) Third trophic level
IV) Grass
Answer and explanation
Answer: (4)
Grass is the first trophic level, rabbit the second, crow the third and vulture the fourth. Thus P-II, Q-III, R-IV, S-I. Chapter: Ecosystem.
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