What does Ecology and Environment cover for NEET Biology?

6 lessons: Biodiversity Loss Conservation, Biodiversity Patterns, Ecosystem Productivity Decomposition, Ecosystem Structure Function, Population Attributes Growth and Population Interactions.

How often has Ecology and Environment come up in NEET past papers?

Our set of verified past papers has 58 questions from this unit, from NEET 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.

Is the Ecology and Environment material free?

Yes. All 6 lessons and 48 practice questions are free, with no login needed.

Ecology and Environment

6 lessons

Topic index in NCERT order

6 of 6 lessons by the NCERT chapter they teach from, in book order. The page is the first printed page of your NCERT book the lesson cites; PYQs are the past NEET questions on that topic.

Biodiversity Loss Conservation

8 MCQs10 PYQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Biodiversity Patterns

8 MCQs5 PYQs4 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Ecosystem Productivity Decomposition

8 MCQs11 PYQs4 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Ecosystem Structure Function

8 MCQs4 PYQsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (2)

Population Attributes Growth

8 MCQs8 PYQs3 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (2)

Population Interactions

8 MCQs12 PYQsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (2)

NCERT lines NEET tested in this unit

Each line with its printed NCERT page and the past NEET questions that tested it.

Past-paper questions from this unit

58 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025, 2026. Answers verified against NTA official keys.

By year in our set: 2020 (7) · 2021 (5) · 2022 (12) · 2023 (10) · 2024 (8) · 2025 (9) · 2026 (7)

Lesson: Biodiversity Patterns

NEET 2026

Arrange the following in descending order of number of species in the Amazonian rain forest. (a) Plants (b) Birds (c) Fishes (d) Invertebrates (e) Mammals. Choose the correct answer from the options given below :

1(c) > (b) > (d) > (e) > (a)

2(d) > (a) > (c) > (b) > (e)

3(e) > (b) > (a) > (c) > (d)

4(b) > (a) > (d) > (c) > (e)

NTA Answer: Option 2(final)

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Lesson: Ecosystem Structure Function

NEET 2026

Which of the following are primary consumers in a food chain ?

1Parasites

2Predators

3Herbivores

4Carnivores

NTA Answer: Option 3(final)

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Lesson: Population Attributes Growth

NEET 2026

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 ______.

11 million

25 million

310 million

4100 million

NTA Answer: Option 3(final)

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Lesson: Population Attributes Growth

NEET 2026

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : The logistic growth model of populations is considered more realistic than the exponential growth model. Reason R : Resources are finite. In the light of the above statements, choose the most appropriate answer from the options given below :

1Both A and R are correct and R is the correct explanation of A

2Both A and R are correct but R is not the correct explanation of A

3A is correct but R is not correct

4A is not correct but R is correct

NTA Answer: Option 1(final)

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Lesson: Population Interactions

NEET 2026

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Abingdon tortoise in Galapagos islands became extinct within a decade after goats were introduced. Reason R : Goats were more efficient at browsing than Abingdon tortoise. In the light of the above statements, choose the most appropriate answer from the options given below :

1Both A and R are correct and R is the correct explanation of A

2Both A and R are correct but R is not the correct explanation of A

3A is correct but R is not correct

4A is not correct but R is correct

NTA Answer: Option 1(final)

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Lesson: Population Interactions

NEET 2026

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 :

1A-III, B-IV, C-II, D-I

2A-I, B-II, C-III, D-IV

3A-II, B-I, C-IV, D-III

4A-III, B-I, C-II, D-IV

NTA Answer: Option 4(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2026

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 :

1(a), (b) and (c)

2(a) and (b) only

3(a) and (c) only

4(b) and (c) only

NTA Answer: Option 2(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2025

Which of the following is the unit of productivity of an Ecosystem?

1(KCal m⁻²)yr⁻¹

2gm–2

3KCal m⁻²

4KCal m⁻³

NTA Answer: Option 1(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2025

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:

1Statement I is incorrect but statement II is correct

2Both statement I and statement II are correct

3Both statement I and statement II are incorrect

4Statement I is correct but statement II is incorrect

NTA Answer: Option 4(final)

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Lesson: Population Attributes Growth

NEET 2025

Which one of the following equations represents the Verhulst-Pearl Logistic Growth of population?

1dN/dt = N((r − K)/K)

2dN/dt = r((K − N)/K)

3dN/dt = rN((K − N)/K)

4dN/dt = rN((N − K)/N)

NTA Answer: Option 3(final)

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Lesson: Population Interactions

NEET 2025

Given below are two statements : Statement I : Fig fruit is a non-vegetarian fruit as it has enclosed fig wasps in it. Statement II : Fig wasp and fig tree exhibit mutual relationship as fig wasp completes its life cycle in fig fruit and fig fruit gets pollinated by fig wasp. In the light of the above statements, choose the most appropriate answer from the options given below :

1Statement I is incorrect but statement II is correct

2Both statement I and statement II are correct

3Both statement I and statement II are incorrect

4Statement I is correct but statement II is incorrect

NTA Answer: Option 3(final)

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Lesson: Biodiversity Loss Conservation

NEET 2025

Match List I with List II: List I List II A. The Evil Quartet I. Cryopreservation B. Ex situ conservation II. Alien species invasion C. Lantana camara III. Causes of biodiversity losses D. Dodo IV. Extinction Choose the option with all correct matches.

1A-III, B-II, C-IV, D-I

2A-III, B-II, C-I, D-IV

3A-III, B-I, C-II, D-IV

4A-III, B-IV, C-II, D-I

NTA Answer: Option 3(final)

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Lesson: Ecosystem Structure Function

NEET 2025

Who is known as the father of Ecology in India?

1Birbal Sahni

2S.R. Kashyap

3Ramdeo Misra

4Ram Udar

NTA Answer: Option 3(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2025

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:

1Statement I is incorrect but statement II is correct

2Both statement I and statement II are correct

3Both statement I and statement II are incorrect

4Statement I is correct but statement II is incorrect

NTA Answer: Option 4(final)

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Lesson: Biodiversity Loss Conservation

NEET 2025

Which one of the following is an example of ex-situ conservation?

1Protected areas

2National Park

3Wildlife Sanctuary

4Zoos and botanical gardens

NTA Answer: Option 4(final)

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Lesson: Population Interactions

NEET 2025

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

1Amensalism

2Commensalism

3Mutualism

4Predation

NTA Answer: Option 2(final)

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Lesson: Biodiversity Loss Conservation

NEET 2024Revised key

The type of conservation in which the threatened species are taken out from their natural habitat and placed in special setting where they can be protected and given special care is called;

1in-situ conservation

2Biodiversity conservation

3Semi-conservative method

4Sustainable development

NTA Answer: Option 2(revised_final)

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Lesson: Population Attributes Growth

NEET 2024Revised key

The equation of Verhulst-Pearl logistic growth is dN/dt = rN[(K − N)/K]. From this equation, K indicates:

1Intrinsic rate of natural increase

2Biotic potential

3Carrying capacity

4Population density

NTA Answer: Option 3(revised_final)

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Lesson: Biodiversity Loss Conservation

NEET 2024Revised key

These are regarded as major causes of biodiversity loss: A. Over exploitation B. Co-extinction C. Mutation D. Habitat loss and fragmentation E. Migration Choose the correct option:

1A, C and D only

2A, B, C and D only

3A, B and E only

4A, B and D only

NTA Answer: Option 4(revised_final)

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Lesson: Biodiversity Loss Conservation

NEET 2024Revised key

List of endangered species was released by-

1GEAC

2WWF

3FOAM

4IUCN

NTA Answer: Option 4(revised_final)

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Lesson: Biodiversity Patterns

NEET 2024Revised key

Tropical regions show greatest level of species richness because A. Tropical latitudes have remained relatively undisturbed for millions of years, hence more time was available for species diversification. B. Tropical environments are more seasonal. C. More solar energy is available in tropics. D. Constant environments promote niche specialization. E. Tropical environments are constant and predictable. Choose the correct answer from the options given below.

1A, C, D and E only

2A and B only

3A, B and E only

4A, B and D only

NTA Answer: Option 1(revised_final)

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Lesson: Biodiversity Patterns

NEET 2024Revised key

Match List I with List II List I List II A. Robert May I. Species-Area relationship B. Alexander von Humboldt II. Long term ecosystem experiment using out door plots C. Paul Ehrlich III. Global species diversity at about 7 million D. David Tilman IV. Rivet popper hypothesis Choose the correct answer from the options given below:

1A-II, B-III, C-I, D-IV

2A-III, B-I, C-IV, D-II

3A-I, B-III, C-II, D-IV

4A-III, B-IV, C-II, D-I

NTA Answer: Option 2(revised_final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2024Revised key

In an ecosystem if 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?

1(x/10) (kcal m⁻²) yr⁻¹

2x (kcal m⁻²) yr⁻¹

310x (kcal m⁻²) yr⁻¹

4(100x/3x) (kcal m⁻²) yr⁻¹

NTA Answer: Option 3(revised_final)

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Lesson: Population Interactions

NEET 2024Revised key

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 :

1Both Statement I and Statement II are true.

2Both Statement I and Statement II are false.

3Statement I is true but Statement II is false.

4Statement I is false but Statement II is true.

NTA Answer: Option 4(revised_final)

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Lesson: Biodiversity Loss Conservation

NEET 2023

Among ‘The Evil Quartet’, which one is considered the most important cause driving extinction of species?

1Over exploitation for economic gain

2Alien species invasions

3Co-extinctions

4Habitat loss and fragmentation

NTA Answer: Option 4(final)

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Lesson: Biodiversity Loss Conservation

NEET 2023

The historic Convention on Biological Diversity, ‘The Earth Summit’ was held in Rio de Janeiro in the year

11992

21986

32002

41985

NTA Answer: Option 1(final)

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NEET 2023

The thickness of ozone in a column of air in the atmosphere is measured in terms of :

1Decibels

2Decameter

3Kilobase

4Dobson units

NTA Answer: Option 4(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2023

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:

1B, C, D only

2C, D, E only

3D, E, A only

4A, B, C only

NTA Answer: Option 4(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2023

In the equation GPP − R = NPP GPP is Gross Primary Productivity NPP is Net Primary Productivity R here is ________.

1Respiratory quotient

2Respiratory loss

3Reproductive allocation

4Photosynthetically active radiation

NTA Answer: Option 2(final)

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Lesson: Population Interactions

NEET 2023

Match List I with List II : List I List II (Interaction) (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:

1A-IV, B-I, C-II, D-III

2A-IV, B-III, C-I, D-II

3A-III, B-I, C-IV, D-II

4A-IV, B-II, C-I, D-III

NTA Answer: Option 1(final)

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Lesson: Population Interactions

NEET 2023

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:

1Both Statement I and Statement II are false.

2Statement I is correct Statement II is false.

3Statement I is incorrect but Statement II is true.

4Both Statement I and Statement II are true.

NTA Answer: Option 2(final)

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NEET 2023

Given below are two statements: Statement I: Electrostatic precipitator is most widely used in thermal power plant. Statement II : Electrostatic precipitator in thermal power plant removes ionising radiations. In the light of the above statements, choose the most appropriate answer from the options given below:

1Both Statement I and Statement II are incorrect.

2Statement I is correct but Statement II is incorrect.

3Statement I is incorrect but Statement II is correct.

4Both Statement I and Statement II are correct.

NTA Answer: Option 2(final)

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Lesson: Population Interactions

NEET 2023

Match List I with List II. List I List II (Interacting species) (Name of interaction) A. A Leopard and a Lion in a forest/grassland I. Competition B. A Cuckoo laying egg in a Crow’s nest II. Brood parasitism C. Fungi and root of a higher plant in Mycorrhizae III. Mutualism D. A cattle egret and a Cattle in a field IV. Commensalism Choose the correct answer from the options given below.

1A-I, B-II, C-IV, D-III

2A-III, B-IV, C-I, D-II

3A-II, B-III, C-I, D-IV

4A-I, B-II, C-III, D-IV

NTA Answer: Option 4(final)

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Lesson: Population Attributes Growth

NEET 2023

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 percent individuals of pre-reproductive age is largest followed by reproductive and post reproductive age groups D. Stable age pyramid IV. The percent individuals of pre-reproductives and reproductive age group are same Choose the correct answer from the options given below:

1A-II, B-III, C-I, D-IV

2A-II, B-IV, C-I, D-III

3A-II, B-IV, C-III, D-I

4A-II, B-I, C-III, D-IV

NTA Answer: Option 4(final)

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NEET 2022

The device which can remove particulate matter present in the exhaust from a thermal power plant is :

1Catalytic Convertor

2STP

3Incinerator

4Electrostatic Precipitator

NTA Answer: Option 4(final)

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Lesson: Biodiversity Loss Conservation

NEET 2022

Which of the following is not a method of ex situ conservation?

1Cryopreservation

2In vitro fertilization

3National Parks

4Micropropagation

NTA Answer: Option 3(final)

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Lesson: Population Interactions

NEET 2022

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

1It is necessitated by nature to maintain the ecological balance

2It helps in maintaining species diversity in a community

3It might lead to extinction of a species

4Both the interacting species are negatively impacted

NTA Answer: Option 4(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2022

Given below are two statements: Statement I: Decomposition is a process in which the detritus is degraded into simpler substances by microbes. Statement II: Decomposition is faster if the detritus is rich in lignin and chitin. In the light of the above statements, choose the correct answer from the options given below:

1Statement I is incorrect but Statement II is correct

2Both Statement I and Statement II are correct

3Both Statement I and Statement II are incorrect

4Statement I is correct but Statement II is incorrect

NTA Answer: Option 4(final)

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Lesson: Biodiversity Loss Conservation

NEET 2022

Habitat loss and fragmentation, over exploitation, alien species invasion and co-extinction are causes for:

1Natality

2Population explosion

3Competition

4Biodiversity loss

NTA Answer: Option 4(final)

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Lesson: Ecosystem Structure Function

NEET 2022

Which one of the following will accelerate phosphorus cycle?

1Rain fall and storms

2Burning of fossil fuels

3Volcanic activity

4Weathering of rocks

NTA Answer: Option 4(final)

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NEET 2022

The entire fleet of buses in Delhi were converted to CNG from diesel. In reference to this, which one of the following statements is false?

1It cannot be adulterated like diesel

2CNG burns more efficiently than diesel

3The same diesel engine is used in CNG buses making the cost of conversion low

4It is cheaper than diesel

NTA Answer: Option 3(final)

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Lesson: Population Interactions

NEET 2022

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

1Competition

2Predation

3Amensalim

4Commensalism

NTA Answer: Option 2(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2022

Detritivores breakdown detritus into smaller particles. This process is called:

1Decomposition

2Catabolism

3Fragmentation

4Humification

NTA Answer: Option 3(final)

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Lesson: Population Attributes Growth

NEET 2022

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.

1zero

20.1

310

41.0

NTA Answer: Option 2(final)

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Lesson: Biodiversity Loss Conservation

NEET 2022

In-situ conservation refers to:

1Conserve only extinct species

2Protect and conserve the whole ecosystem

3Conserve only high-risk species

4Conserve only endangered species

NTA Answer: Option 2(final)

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NEET 2022

Given below are two statements: Statements I : In a scrubber the exhaust from the thermal plant is passed through the electric wires to charge the dust particles. Statement II : Particulate matter (PM 2.5) cannot be removed by scrubber but can be removed by an electrostatic precipitator. In the light of the above statements, choose the most appropriate answer from the options given below :

1Statement I is incorrect but Statement II is correct

2Both Statement I and Statement II are correct

3Both Statement I and Statement II are incorrect

4Statement I is correct but Statement II is incorrect

NTA Answer: Option 1(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2021

The amount of nutrients, such as carbon, nitrogen, phosphorus and calcium present in the soil at any given time, is referred as :

1Standing crop

2Climax

3Climax community

4Standing state

NTA Answer: Option 4(final)

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Lesson: Population Interactions

NEET 2021

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

1Predation

2Resource partitioning

3Competitive release

4Mutualism

NTA Answer: Option 2(final)

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Lesson: Population Interactions

NEET 2021

Amensalism can be represented as:

1Species A (+); Species B

2Species A (–); Species B

3Species A (+); Species B (+)

4Species A (–); Species B (–)

NTA Answer: Option 2(final)

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Lesson: Population Attributes Growth

NEET 2021

In the exponential growth equation Nt = Noert, e represents

1The base of geometric logarithms

2The base of number logarithms

3The base of exponential logarithms

4The base of natural logarithms

NTA Answer: Option 4(final)

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NEET 2021

Match List-I with List - II List - I List - II (a) Allen’s Rule (b) Physiological adaptation (c) Behavioural adaptation (d) Biochemical adaptation (i) Kangaroo rat (ii) Desert lizard (iii) Marine fish at depth (iv) Polar seal Choose the correct answer from the options given below. (a) (b) (c) (d)

1(iv) (iii) (ii) (i)

2(iv) (ii) (iii) (i)

3(iv) (i) (iii) (ii)

4(iv) (i) (ii) (iii)

NTA Answer: Option 4(final)

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NEET 2020

Montreal protocol was signed in 1987 for control of :

1Disposal of e-wastes

2Transport of Genetically modified organisms from one country to another

3Emission of ozone depleting substances

4Release of Green House gases

NTA Answer: Option 3(final)

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Lesson: Biodiversity Patterns

NEET 2020

According to Robert May, the global species diversity is about :

17 million

21.5 million

320 million

450 million

NTA Answer: Option 1(final)

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Lesson: Ecosystem Structure Function

NEET 2020

Match the trophic levels with their correct species examples in grassland ecosystem. (a) Fourth trophic level (i) Crow (b) Second trophic level (ii) Vulture (c) First trophic level (iii) Rabbit (d) Third trophic level (iv) Grass Select the correct option : (a) (b) (c) (d)

1(i) (ii) (iii) (iv)

2(ii) (iii) (iv) (i)

3(iii) (ii) (i) (iv)

4(iv) (iii) (ii) (i)

NTA Answer: Option 2(final)

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Lesson: Ecosystem Productivity Decomposition

NEET 2020

In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct ?

1There is no relationship between Gross primary productivity and Net primary productivity.

2Gross primary productivity is always less than net primary productivity.

3Gross primary productivity is always more than net primary productivity.

4Gross primary productivity and Net primary productivity are one and same.

NTA Answer: Option 3(final)

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NEET 2020

Snow-blindness in Antarctic region is due to :

1Damage to retina caused by infra-red rays

2Freezing of fluids in the eye by low temperature

3Inflammation of cornea due to high dose of UV-B radiation

4High reflection of light from snow

NTA Answer: Option 3(final)

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Lesson: Biodiversity Patterns

NEET 2020

Which of the following regions of the globe exhibits highest species diversity ?

1Amazon forests

2Western Ghats of India

3Madagascar

4Himalayas

NTA Answer: Option 1(final)

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Lesson: Population Attributes Growth

NEET 2020

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

1Species interaction

2Sex ratio

3Natality

4Mortality

NTA Answer: Option 1(final)

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Exam traps and common mistakes in this unit

Lesson: Population Interactions

Trap

Mutualism (+,+) vs commensalism (+,0) confusion

Category: Similar Terms

Mutualism benefits BOTH; commensalism benefits one, neutral for the other; parasitism +,−; predation +,−.

When it triggers

Question presents organism-pair interaction and asks for type.

How to avoid

Tabulate effects on each partner: (+,+), (+,0), (+,−), (−,−), (0,−), (0,0).

Lesson: Ecosystem Productivity Decomposition

Mistake

Says pyramid of energy can be inverted (it's always upright).

Root cause: concept gap

Correction

Pyramid of ENERGY is ALWAYS upright (10% law guarantees decreasing energy at higher trophic levels). Pyramid of NUMBER and BIOMASS can be inverted (e.g. ocean: small algae < large zooplankton at one moment).

Lesson: Population Attributes Growth

Mistake

Lists humans as r-selected (they are K-selected).

Root cause: term confusion

Correction

K-selected: large body, few offspring with high parental investment, long-lived (whales, humans, elephants). r-selected: small body, many offspring, low investment, short-lived (insects, weeds).

Formulas in this unit

Lesson: Biodiversity Patterns

Species-area relationship

lo g S = lo g C + Z lo g A

Number of species S in area A increases as a power law. Z (slope) = 0.1-0.2 for small areas, 0.6-1.2 for continents.

Symbol	Quantity	SI Unit
S	species number	-
A	area	-
Z	slope	-
C	intercept	-

Valid when

Within a biogeographic region

Lesson: Ecosystem Productivity Decomposition

Lindeman's 10% law of energy transfer

E_{n + 1} = 0.10 E_{n}

Approximately 10% of energy at one trophic level is transferred to the next; rest dissipated as heat.

Symbol	Quantity	SI Unit
E_n	energy at level n	kcal/m²

Valid when

Idealised trophic transfer

Lesson: Population Attributes Growth

Logistic population growth

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

Population grows exponentially at small N; growth slows as N approaches K (carrying capacity); equilibrium at N = K.

Symbol	Quantity	SI Unit
N	population size	-
r	intrinsic rate of increase	/time
K	carrying capacity	-

Valid when

Verhulst-Pearl assumptions
Limiting resource

NEET question patterns in this unit

Unit-wide

Population growth, interactions, ecosystem, biodiversity, conservation, pollution

RecallMedium

Common distractors

population interaction type confusion

Six interaction types form a 2x2 effect matrix (+,+), (+,-), (+,0), (-,-), (-,0), (0,0). Students who have memorised the symbols cannot always assign real organism pairs correctly: barnacles on a whale body = commensalism (+,0) not mutualism (+,+); mycorrhizal fungi on plant roots = mutualism not parasitism. The most common error is selecting mutualism for commensalism examples because both organisms are 'associated'.

ecological pyramid inversion error

Students learn that 'ecological pyramids can be inverted' from the examples of the number pyramid (tree-insects-birds) and the ocean biomass pyramid. They over-apply this to energy pyramids. The 10% law guarantees that energy ALWAYS decreases at each trophic level -- no realistic scenario inverts the energy pyramid. Questions ask which pyramid type 'can be inverted'; students select energy because they generalise the inversion rule.

k r selection confusion

K-selected species (large body, few offspring, high parental investment, long-lived: whales, humans, elephants) are confused with r-selected (small body, many offspring, no parental care: insects, frogs, bacteria). Students who associate 'reproducing as humans do = normal' call humans r-selected, or who associate 'complex animal = cared-for offspring' call oysters K-selected.

speciation type confusion

Sympatric speciation occurs in the same geographic area without physical isolation (e.g., polyploidy); allopatric speciation requires a geographic barrier. Students who cannot recall the Greek roots (sym = same, allo = different) confuse the two when a question describes a real-world scenario and asks which speciation type it illustrates.

Questions about this unit

What does Ecology and Environment cover for NEET Biology?: 6 lessons: Biodiversity Loss Conservation, Biodiversity Patterns, Ecosystem Productivity Decomposition, Ecosystem Structure Function, Population Attributes Growth and Population Interactions.
How often has Ecology and Environment come up in NEET past papers?: Our set of verified past papers has 58 questions from this unit, from NEET 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.
Is the Ecology and Environment material free?: Yes. All 6 lessons and 48 practice questions are free, with no login needed.

Ecology and Environment

Topic index in NCERT order

Class 12 Biology, Chapter 11: Organisms and Populations

Class 12 Biology, Chapter 12: Ecosystem

Class 12 Biology, Chapter 13: Biodiversity and Conservation

Biodiversity Loss Conservation

Biodiversity Patterns

Ecosystem Productivity Decomposition

Ecosystem Structure Function

Population Attributes Growth

Population Interactions

NCERT lines NEET tested in this unit

Past-paper questions from this unit

Exam traps and common mistakes in this unit

Mutualism (+,+) vs commensalism (+,0) confusion

When it triggers

How to avoid

Says pyramid of energy can be inverted (it's always upright).

Correction

Lists humans as r-selected (they are K-selected).

Correction

Formulas in this unit

Species-area relationship

Valid when

Lindeman's 10% law of energy transfer

Valid when

Logistic population growth

Valid when

NEET question patterns in this unit

Population growth, interactions, ecosystem, biodiversity, conservation, pollution

Common distractors

Questions about this unit