Organisms and Populations

Class 12

18 previous-year questions from this chapter every option and the correct answer, free · where the marks are

1. Organism and its environment; adaptations

Exam focus: Regulation isn't always physiological: plenty of conformers — reptiles, most famously — keep their body temperature workable purely through behaviour, basking in the sun or retreating to shade, without ever regulating internally the way a true homeotherm does.

Organism and Its Environment; Adaptations

NCERT Wallah

Introductory lecture on ecology and the organism-environment relationship (biotic/abiotic factors), covering adaptations as part of the same session per NCERT sequence.

BotanyNEET 2025show ▾

Who is known as the father of ecology in India?

A.S. R. Kashyap
B.Ramdeo Misra✓
C.Ram Udar
D.Birbal Sahni

Solution

Ramdeo Misra, who established ecology as a discipline at Banaras Hindu University, is regarded as the father of Indian ecology.

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ZoologyNEET 2021show ▾

Match List-I with List-II.

List-I	List-II
(a) Allen's rule	(i) Kangaroo rat
(b) Physiological adaptation	(ii) Desert lizard
(c) Behavioural adaptation	(iii) Marine fish at depth
(d) Biochemical adaptation	(iv) Polar seal

Choose the correct answer from the options given below:

A.(a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
B.(a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
C.(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)✓
D.(a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)

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2. Population attributes, growth models and interactions

Exam focus: Exponential growth (dN/dt = rN) describes a population with no resource ceiling and produces an ever-steepening J-shaped curve that no real population sustains for long; logistic growth (dN/dt = rN(K-N)/K) is the realistic, resource-limited S-shaped curve NEET actually expects you to identify.

Organisms and Populations — Full Chapter in 58 Minutes

Competition Wallah

Population attributes, exponential vs logistic growth, and the +/-, -/-, +/+ interaction types NEET tests as a set, run through together.

ZoologyNEET 2025show ▾

Given below are two statements: Statement I: The fig fruit is a non-vegetarian fruit as it has enclosed fig wasps in it. Statement II: The fig wasp and fig tree exhibit a mutual relationship, as the fig wasp completes its life cycle in the fig fruit and the fig fruit gets pollinated by the fig wasp. 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

Solution

The official key marks both statements incorrect: the fig is a syconium (an inflorescence, not a true fruit) and the wasp inside it does not make it 'non-vegetarian'; and while fig and wasp are indeed mutualists, the statement as framed — the wasp completing its life cycle in a 'fruit' — was not accepted.

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BotanyNEET 2025show ▾

Epiphytes growing on a mango branch are an example of which of the following?

A.Commensalism✓
B.Mutualism
C.Predation
D.Amensalism

Solution

An epiphyte uses the mango branch only for support and takes nothing from it — the orchid benefits and the tree is unaffected, which is commensalism.

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ZoologyNEET 2025show ▾

Which one of the following equations represents the Verhulst–Pearl logistic growth of a population?

A. $\frac{d N}{d t} = r (\frac{K - N}{K})$
B. $\frac{d N}{d t} = r N (\frac{K - N}{K})$ ✓
C. $\frac{d N}{d t} = r N (\frac{N - K}{N})$
D. $\frac{d N}{d t} = r K (\frac{N}{K})$

Solution

The Verhulst–Pearl logistic equation is $\frac{d N}{d t} = r N (\frac{K - N}{K})$ , growth slowing as the population $N$ approaches the carrying capacity $K$ .

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ZoologyNEET 2024show ▾

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.Both Statement I and Statement II are false.
B.Statement I is true but Statement II is false.
C.Statement I is false but Statement II is true.✓
D.Both Statement I and Statement II are true.

Solution

Gause's principle concerns species competing for the same limited resource — Statement I, which says 'different resources', is wrong. That the inferior competitor is eliminated when resources are limiting is a correct reading of the principle — Statement II is true.

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BotanyNEET 2024show ▾

The equation of Verhulst–Pearl logistic growth is

\frac{d N}{d t} = r N (\frac{K - N}{K})

. From this equation,

K

indicates:

A.Biotic potential
B.Carrying capacity✓
C.Population density
D.Intrinsic rate of natural increase

Solution

In the logistic equation $\frac{d N}{d t} = r N (\frac{K - N}{K})$ , $K$ is the carrying capacity — the maximum population the habitat can support; $r$ is the intrinsic rate of natural increase.

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BotanyNEET 2023show ▾

Match List I with List II.

List I (Interaction)	List II (Species A and B)
A. Mutualism	I. +(A), 0(B)
B. Commensalism	II. –(A), 0(B)
C. Amensalism	III. +(A), –(B)
D. Parasitism	IV. +(A), +(B)

Choose the correct answer from the options given below:

A.A-IV, B-II, C-I, D-III
B.A-IV, B-I, C-II, D-III✓
C.A-IV, B-III, C-I, D-II
D.A-III, B-I, C-IV, D-II

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BotanyNEET 2023show ▾

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 the 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 true.
B.Both Statement I and Statement II are false.
C.Statement I is correct but Statement II is false.✓
D.Statement I is incorrect but Statement II is true.

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ZoologyNEET 2023show ▾

Match List I with List II.

List I	List II
A. Logistic growth	I. Unlimited resource availability condition
B. Exponential growth	II. Limited resource availability condition
C. Expanding age pyramid	III. The percentage of individuals of pre-reproductive age is largest, followed by reproductive and post-reproductive age groups
D. Stable age pyramid	IV. The percentages of individuals of pre-reproductive and reproductive age groups are the same

Choose the correct answer from the options given below:

A.A-II, B-I, C-III, D-IV✓
B.A-II, B-III, C-I, D-IV
C.A-II, B-IV, C-I, D-III
D.A-II, B-IV, C-III, D-I

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ZoologyNEET 2023show ▾

Match List I with List II.

List I (Interacting species)	List II (Name of interaction)
A. A leopard and a lion in a forest/grassland	I. Competition
B. A cuckoo laying an egg in a crow's nest	II. Brood parasitism
C. Fungi and the root of a higher plant in mycorrhizae	III. Mutualism
D. A cattle egret and cattle in a field	IV. Commensalism

Choose the correct answer from the options given below:

A.A-I, B-II, C-III, D-IV✓
B.A-I, B-II, C-IV, D-III
C.A-III, B-IV, C-I, D-II
D.A-II, B-III, C-I, D-IV

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BotanyNEET 2022show ▾

Which one of the following statements cannot be connected to predation?

A.It is necessitated by nature to maintain the ecological balance
B.It helps in maintaining species diversity in a community
C.It might lead to extinction of a species
D.Both the interacting species are negatively impacted✓

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ZoologyNEET 2022show ▾

If 8 Drosophila in a laboratory population of 80 died during a week, the death rate in the population is ______ individuals per Drosophila per week.

A.Zero
B.0.1✓
C.10
D.1.0

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BotanyNEET 2022show ▾

While explaining interspecific interactions of populations, a (+) sign is assigned for beneficial interaction, a (–) sign for detrimental interaction and (0) for neutral interaction. Which of the following interactions can be assigned (+) for one species and (–) for the other species involved in the interaction?

A.Competition
B.Predation✓
C.Amensalism
D.Commensalism

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BotanyNEET 2021show ▾

In spite of interspecific competition in nature, which mechanism might the competing species have evolved for their survival?

A.Resource partitioning✓
B.Competitive release
C.Mutualism
D.Predation

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BotanyNEET 2021show ▾

Amensalism can be represented as:

A.Species A (–); Species B (0)✓
B.Species A (+); Species B (+)
C.Species A (–); Species B (–)
D.Species A (+); Species B (0)

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BotanyNEET 2021show ▾

In the exponential growth equation

N_{t} = N_{0} e^{r t}

,

e

represents:

A.The base of number logarithms
B.The base of exponential logarithms
C.The base of natural logarithms✓
D.The base of geometric logarithms

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BotanyNEET 2020show ▾

Which of the following is not an attribute of a population?

A.Sex ratio
B.Natality
C.Mortality
D.Species interaction✓

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