NEET Ecosystem PYQs & Practice Questions

10 free NEET Biology questions on Ecosystem, starting with previous year questions (2016–2026). Tap “Show answer” to check each one. No login needed.

Topics: Nutritional Mode of Decomposers · What Mineralisation Releases · Units for Expressing Productivity · Identifying a Non-Producer · Efficiency of Photosynthetic Energy Capture · Herbivore Consumption of Net Primary Productivity · Pattern of Change During Ecological Succession · State of a Climax Community · Reservoir of a Gaseous Biogeochemical Cycle · Determining Trophic Level from Carbon Transfer · Primary Productivity Calculation · Primary Productivity

Q1NEET 2026Energy Flow and Ecological Pyramids
Which of the following statements are correct? (a) Energy flow from producers to consumers is unidirectional (b) Energy pyramid can never be inverted (c) Transfer of energy follows the 1% law Choose the correct answer from the options given below:
- A. (a) and (b) only
- B. (a) and (c) only
- C. (b) and (c) only
- D. (a), (b) and (c)
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Answer: A — (a) and (b) only
Energy flow in an ecosystem is unidirectional, moving from producers to consumers (unlike nutrient cycling, which is cyclic) -- (a) is correct. Only about 1% of the solar energy incident on producers is typically captured and converted into chemical (net primary productive) energy, sometimes referred to as the 'one percent law' of energy capture efficiency by autotrophs -- (c) is correct in this sense. (Note: pyramid of energy is generally taught as always upright, but per this question's answer key, (b) is not included among the correct statements.)
Q2NEET 2026Matching decomposition process to description
Match List I with List II: List I — A. Decomposition, B. Detritus, C. Mineralisation, D. Humification. List II — I. Accumulation of dark coloured amorphous colloidal substance, II. Release of inorganic nutrients by the activity of microbes in soil, III. Breaking down of complex organic matter into inorganic substances, IV. Dead remains of plants and animals including fecal matter.
- A. A-III, B-IV, C-II, D-I
- B. A-IV, B-III, C-I, D-II
- C. A-I, B-II, C-III, D-IV
- D. A-III, B-IV, C-I, D-II
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Answer: C — A-I, B-II, C-III, D-IV
Decomposition is the breaking down of complex organic matter (III); detritus is dead remains (IV); mineralisation is release of inorganic nutrients (II); humification is accumulation of dark amorphous colloidal substance (I). A-III, B-IV, C-II, D-I.
Q3NEET 2026Pyramids that are generally inverted
Ecological pyramids represent the relationship between the organisms at different trophic levels and they are generally inverted for:
- A. Pyramid of number in grassland
- B. Pyramid of energy in pond ecosystem
- C. Pyramid of biomass in grassland
- D. Pyramid of biomass in sea
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Answer: C — Pyramid of biomass in grassland
In a pond/sea ecosystem, pyramid of biomass is generally inverted since the biomass of phytoplankton (producers) is less than that of zooplankton/fish at higher trophic levels.
Q4NEET 2025Primary Productivity
Given below are two statements : Statement I : The primary source of energy in an ecosystem is solar energy. Statement II : The rate of production of organic matter during photosynthesis in an ecosystem is called net primary productivity (NPP). In the light of the above statements, choose the most appropriate answer from the options given below :
- A. Both statement I and statement II are correct
- B. Both statement I and statement II are incorrect
- C. Statement I is correct but statement II is incorrect
- D. Statement I is incorrect but statement II is correct
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Answer: B — Both statement I and statement II are incorrect
Statement I is correct: solar energy is the primary source of energy in an ecosystem. Statement II is incorrect: the rate of production of organic matter during photosynthesis is called Gross Primary Productivity (GPP), not Net Primary Productivity (NPP, which is GPP minus respiratory losses).

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Q5NEET 2025Father of Ecology in India
Who is known as the father of Ecology in India?
- A. S.R. Kashyap
- B. Ramdeo Misra
- C. Ram Udar
- D. Birbal Sahni
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Answer: A — S.R. Kashyap
Ramdeo Misra is revered as the Father of Ecology in India.
Q6NEET 2025Unit of Ecosystem Productivity
Which of the following is the unit of productivity of an Ecosystem?
- A. gm⁻²
- B. K Cal m⁻²
- C. K Cal m⁻³
- D. (K Cal M⁻²)yr⁻¹
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Answer: C — K Cal m⁻³
The rate of biomass production is called productivity. It is expressed in terms of gm⁻² yr⁻¹ or (kcal m⁻²) yr⁻¹ to compare the productivity of different ecosystems.
Q7NEET 2025Unidirectional Energy Flow and Second Law of Thermodynamics
Given below are two statements: Statement I: In ecosystem, there is unidirectional flow of energy of sun from producers to consumers. Statement II: Ecosystems are exempted from 2nd law of thermodynamics. In the light of the above statements, choose the most appropriate answer from the options given below:
- A. Both statement I and statement II are correct
- B. Both statement I and statement II are incorrect
- C. Statement I is correct but statement II is incorrect
- D. Statement I is incorrect but statement II is correct
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Answer: B — Both statement I and statement II are incorrect
Statement I is correct - energy flows unidirectionally from the sun to producers to consumers in an ecosystem. Statement II is incorrect - ecosystems are NOT exempt from the 2nd law of thermodynamics; they require a constant supply of energy to synthesize the molecules needed to maintain structure and function.
Q8NEET 2024Primary Productivity Calculation
In an ecosystem the Net Primary productivity (NPP) of first trophic level is 100x (kcal m⁻²) yr⁻¹, what would be the GPP (Gross Primary Productivity) of the third trophic level of the same ecosystem.
- A. 10x (kcal m⁻²) yr⁻¹
- B. 100x/3x (kcal m⁻²) yr⁻¹
- C. x/10 (kcal m⁻²) yr⁻¹
- D. x (kcal m⁻²) yr⁻¹
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Answer: C — x/10 (kcal m⁻²) yr⁻¹
Using the 10% law of energy transfer across trophic levels: NPP of first trophic level (producers) = 100x. Energy reaching second trophic level = 10x. Energy reaching third trophic level (GPP, taken as equal to energy received) = x (kcal m⁻²) yr⁻¹.

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Q9NEET 2023Primary Productivity
In the equation GPP - R = NPP, where GPP is Gross Primary Productivity and NPP is Net Primary Productivity, R here is ______.
- A. Respiratory quotient
- B. Respiratory loss
- C. Reproductive allocation
- D. Photosynthetically active radiation
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Answer: A — Respiratory quotient
Net Primary Productivity (NPP) is Gross Primary Productivity (GPP) minus respiratory losses (R) by plants. So R stands for respiratory loss.
Q10NEET 2023Decomposition - Detritus Food Chain
Identify the correct statements: A. Detrivores perform fragmentation. B. The humus is further degraded by some microbes during mineralization. C. Water soluble inorganic nutrients go down into the soil and get precipitated by a process called leaching. D. The detritus food chain begins with living organisms. E. Earthworms break down detritus into smaller particles by a process called catabolism. Choose the correct answer from the options given below.
- A. B, C, D only
- B. C, D, E only
- C. D, E, A only
- D. A, B, C only
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Answer: C — D, E, A only
Statement A is correct — detritivores (like earthworms) perform fragmentation of detritus into smaller particles. Statement B is correct — humus is further degraded by microbes during mineralization, releasing inorganic nutrients. Statement C is correct — water-soluble inorganic nutrients leach down into the soil. Statement D is incorrect — the detritus food chain begins with dead organic matter, not living organisms. Statement E is incorrect — earthworms break down detritus by fragmentation, not 'catabolism' as a named process. So A, B, C only are correct.

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