NEET Organisms and Populations PYQs & Practice Questions

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

Topics: Definition of Autecology · Definition of an Ecotone · Definition of the Biosphere · Definition of an Ecological Niche · Allen's Rule in Cold Climates · Salinity of Sea Water · Climatic Conditions for Tropical Forest Formation · Forest Canopy and Light Availability · Survival of a Transplanted Forest Herb · Definition of Amensalism · Symbiotic Composition of Lichens · Verhulst-Pearl Logistic Growth - Meaning of K (Carrying Capacity)

Q1NEET 2026Types of Population Interactions
Match List-I with List-II. List-I: (A) Both species are harmed, (B) One species is harmed and the other is benefited, (C) Both species are benefited, (D) One is benefited while the other has no effect List-II: (I) Predation, (II) Mutualism, (III) Competition, (IV) Commensalism Choose the correct answer from the options given below:
- A. A-I, B-II, C-III, D-IV
- B. A-II, B-I, C-IV, D-III
- C. A-III, B-I, C-II, D-IV
- D. A-III, B-IV, C-II, D-I
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Answer: B — A-II, B-I, C-IV, D-III
When both species are harmed, it is competition (III). When one species is harmed and the other benefited, it is predation (I) (predator benefits, prey harmed). When both species are benefited, it is mutualism (II). When one is benefited while the other has no effect, it is commensalism (IV). So A-III, B-I, C-II, D-IV.
Q2NEET 2026Trophic Levels - Primary Consumers
Which of the following are primary consumers in a food chain?
- A. Predators
- B. Herbivores
- C. Carnivores
- D. Parasites
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Answer: A — Predators
Primary consumers are organisms that feed directly on producers (plants), i.e., herbivores.
Q3NEET 2026Population Growth Rate Calculation
Consider a population of 10 million cells. Given the per-capita birth rate of 0.002 (per unit time) and the per-capita death rate of 0.002 (per unit time), the expected number of cells after 10 generations is________.
- A. 5 million
- B. 10 million
- C. 100 million
- D. 1 million
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Answer: A — 5 million
The net growth rate r = birth rate - death rate = 0.002 - 0.002 = 0. With a net growth rate of zero, the population size remains constant (neither growing nor declining) over successive generations, so after 10 generations the population remains 10 million.
Q4NEET 2026Correct statements about population interactions
Choose the correct statements regarding population interactions between two species. A. In both parasitism and commensalism, only one species benefits and the other species is harmed. B. Both species benefit in mutualism. C. Both species benefit in commensalism. D. In parasitism, only one species benefits and the other is harmed. E. In amensalism, one species is harmed and the other is unaffected.
- A. A and B only
- B. B and E only
- C. B, D and E only
- D. A and D only
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Answer: B — B and E only
B (mutualism, both benefit), D (parasitism, one benefits one harmed), and E (amensalism, one harmed one unaffected) are correct. A is false since in commensalism, the other species is unaffected, not harmed; C is false since only one species benefits in commensalism. B, D and E only.

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Q5NEET 2025Types of Species Interactions
Epiphytes that are growing on a mango branch is an example of which of the following?
- A. Commensalism
- B. Mutualism
- C. Predation
- D. Amensalism
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Answer: —
Commensalism is an interaction where one species benefits and the other is neither harmed nor benefited. An orchid growing as an epiphyte on a mango branch is a classic example of commensalism.
Q6NEET 2025Verhulst-Pearl Logistic Growth Equation
Which one of the following equations represents the Verhulst-pearl Logistic Growth of population?
- A. dN/dt = r(K-N)/K
- B. dN/dt = rN(K-N)/K
- C. dN/dt = rN(N-K)/N
- D. dN/dt = N(r-K)/K
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Answer: A — dN/dt = r(K-N)/K
The Verhulst-Pearl Logistic Growth of population is described by the equation dN/dt = rN(K-N)/K, where N is population size, r is intrinsic rate of natural increase, K is carrying capacity.
Q7NEET 2024Verhulst-Pearl Logistic Growth - Meaning of K (Carrying Capacity)
The equation of Verhulst-Pearl logistic growth is dN/dt = rN[(K-N)/K]. From this equation, K indicates:
- A. Carrying capacity
- B. Population density
- C. Intrinsic rate of natural increase
- D. Biotic potential
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Answer: —
In the logistic growth equation, K represents the carrying capacity - the maximum population size that a particular habitat can support. 12th NCERT Page No. 196.
Q8NEET 2024Gause's Competitive Exclusion Principle
Given below are two statements: Statement I: Gause's competitive exclusion principle states that two closely related species competing for different resources cannot exist indefinitely. Statement II: According to Gause's principle, during competition, the inferior will be eliminated. This may be true if resources are limiting. In the light of the above statements, choose the correct answer from the options given below:
- A. Statement I is true but Statement II is false.
- B. Statement I is false but Statement II is true.
- C. Both Statement I and Statement II are true.
- D. Both Statement I and Statement II are false.
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Answer: A — Statement I is true but Statement II is false.
Statement I is false because Gause's principle actually applies to species competing for the SAME limiting resources (not different resources) — two species competing for identical resources cannot coexist indefinitely. Statement II is true as it correctly describes the outcome of such competition when resources are limiting.

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Q9NEET 2023Gause's Competitive Exclusion Principle
Given below are two statements: Statement I: Gause's Competitive Exclusion Principle states that two closely related species competing for the same resources cannot co-exist indefinitely and competitively inferior one will be eliminated eventually. Statement II: In general, carnivores are more adversely affected by competition than herbivores. In the light of the above statements, choose the correct answer from the options given below.
- A. Both Statement I and Statement II are false.
- B. Statement I is correct but Statement II is false.
- C. Statement I is incorrect but Statement II is true.
- D. Both Statement I and Statement II are true.
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Answer: A — Both Statement I and Statement II are false.
Statement I is correct — this is the accurate statement of Gause's Competitive Exclusion Principle. Statement II is false — it is generally herbivores (not carnivores) that are shown to be more adversely affected by interspecific competition in several studies cited in NCERT.
Q10NEET 2023Types of Population Interactions
Match List I (Interaction) with List II (Species A and B effects): A. Mutualism, B. Commensalism, C. Amensalism, D. Parasitism. List II: I. +(A), 0(B), II. -(A), 0(B), III. +(A), -(B), IV. +(A), +(B). Choose the correct answer from the options given below.
- A. A-IV, B-I, C-II, D-III.
- B. A-IV, B-III, C-I, D-II
- C. A-III, B-I, C-IV, D-II
- D. A-IV, B-II, C-I, D-III
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Answer: —
Mutualism benefits both species: +(A), +(B) (A-IV). Commensalism benefits one species while the other is unaffected: +(A), 0(B) (B-I). Amensalism harms one species while the other is unaffected: -(A), 0(B) (C-II). Parasitism benefits one species (parasite) while harming the other (host): +(A), -(B) (D-III). So the correct match is A-IV, B-I, C-II, D-III.

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