Ecology is the study of how organisms interact with each other and their environment. It examines relationships between living things (biotic factors) and non-living elements (abiotic factors) such as air, water, soil, and climate.
Solving questions from Ecology and Environment from previous years helps aspirants understand the trend of questions on this topic. NEET follows a specific pattern in asking questions aboutEcology and Environment. The listed questions and solutions from past years' papers help identify frequently asked topics like Ecosystem, Biodiversity, Food chain and Food web, Biomes, Ecological Niches and Population Dynamics.
Q-1.The equation of Verhulst-Pearl logistic growth is
From this equation, K indicates:
(1) Intrinsic rate of natural increase
(2) Biotic potential
(3) Carrying capacity
(4) Population density
Solution: The correct answer is: (3) Carrying capacity
Explanation: In the Verhulst-Pearl logistic growth equation:
The term K represents the carrying capacity of the environment. Carrying capacity is the maximum population size that an environment can sustain indefinitely, given the available resources such as food, habitat, water, and other necessities.
Q-2. 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 the tropics.
D. Constant environments promote niche specialization.
E. Tropical environments are constant and predictable.
Choose the correct answer from the options given below:
(1) A, C, D and E only
(2) A and B only
(3) A, B and E only
(4) A, B and D only
Solution: - Correct Answer - (1) A, C, D, and E only
Explanation : B) Tropical environments are more seasonal.
False. Tropical environments are less seasonal and more stable throughout the year, which helps in sustaining diverse species.
Q-3 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:
(1) in-situ conservation
(2) Biodiversity conservation
(3) Semi-conservative method
(4) Sustainable development
Solution- The correct answer is - (2) Biodiversity conservation
Solution: The conservation method described in the question refers to ex-situ conservation, where species are removed from their natural habitat and placed in a controlled environment for protection and care. However, ex-situ conservation is not listed among the options. The most appropriate choice from the given options is biodiversity conservation because it broadly includes both in-situ and ex-situ conservation methods.
Q-4. 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:
(1) A, C and D only
(2) A, B, C and D only
(3) A, B and E only
(4) A, B and D only
Solution: Correct Answer: (4) A, B, and D only
Explanation:
The major causes of biodiversity loss include:
(A) Overexploitation – True - Excessive hunting, fishing, logging, and resource extraction lead to species extinction. Example: Overfishing of whales and tuna has drastically reduced their populations.
(B) Co-extinction – True- When one species becomes extinct, species that depend on it may also go extinct. Example: The extinction of host plants can lead to the loss of dependent insect species.
(C) Mutation – False - Mutation is a natural genetic process and does not directly cause biodiversity loss. Some mutations may even be beneficial for species survival.
(D) Habitat loss and fragmentation – True - The destruction of forests, wetlands, and other ecosystems reduces biodiversity. Example: Deforestation in the Amazon threatens thousands of species.
(E) Migration – False - Migration is a natural process in which species move to different habitats for survival. It does not directly cause biodiversity loss.
Q-5. 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 limited.
In the light of the above statements, choose the correct answer from the options given below:
(1) Both Statement I and Statement II are true
(2) Both Statement I and Statement II are false
(3) Statement I is true but Statement II is false
(4) Statement I is false but Statement II is true
Solution: Correct Answer: (4) Statement I is false but Statement II is true.
Explanation: Statement I: Gause’s Competitive Exclusion Principle states that two species competing for the same limited resource cannot coexist indefinitely because one will eventually outcompete the other.
Statement II: According to Gause’s principle, during competition, the inferior will be eliminated. This may be true if resources are limiting.(True)
Q-6. The species of plants that plays a vital role in controlling the relative abundance of other species in a community is called _____ .
(1) alien species
(2) endemic species
(3) exotic species
(4) keystone species
Solution: Correct Answer: (4) Keystone species
Explanation: A keystone species is a species that has a disproportionate impact on its ecosystem relative to its abundance. These species play a vital role in maintaining the structure, diversity, and function of a community by controlling the population of other species.
Q-7. Match List-I with List-II.
Choose the correct answer from the options given below.
(1) (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
(2) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
(3) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
(4) (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
Solution: Correct Answer: (3) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
Explanation:
(a) Allen’s Rule → (iv) Polar seal - Allen’s Rule states that animals in colder regions have shorter limbs, ears, and appendages to minimize heat loss.
(b) Physiological adaptation → (i) Kangaroo rat - Kangaroo rats in deserts survive without drinking water by relying on metabolic water from food and producing highly concentrated urine to prevent water loss.
(c) Behavioural adaptation → (ii) Desert lizard - Desert lizards regulate body temperature by moving between sun and shade instead of relying on physiological changes.
(d) Biochemical adaptation → (iii) Marine fish at depth - Deep-sea marine fish survive extreme pressure conditions due to biochemical adaptations, such as special proteins and enzymes that function efficiently under high pressure.
Q-8. 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 option given below:
(1) B, C, D only
(2) C, D, E only
(3) D, E, A only
(4) A, B, C only
Solution: Correct Answer: (4) A, B, C only
Explanation:
(A) Detrivores perform fragmentation. (True) - Detrivores (e.g., earthworms, millipedes) break detritus into smaller pieces through a process called fragmentation.
(B) The humus is further degraded by some microbes during mineralization. (True) - Mineralization is the breakdown of humus (partially decomposed organic matter) by microbes, releasing inorganic nutrients like nitrates and phosphates into the soil.
(C) Water-soluble inorganic nutrients go down into the soil and get precipitated by a process called leaching. (True) - Leaching is the process where water dissolves nutrients and carries them deeper into the soil, sometimes making them unavailable to plants.
(D) The detritus food chain begins with living organisms. (False) - The detritus food chain (DFC) begins with dead organic matter, not living organisms.
(E) Earthworms break down detritus into smaller particles by a process called catabolism. (False) - Earthworms break down detritus through fragmentation, not catabolism (which refers to enzyme-driven biochemical reactions inside cells).
Q-9. Which of the following statements is not correct?
(1) Pyramid of biomass in sea is generally inverted.
(2) Pyramid of biomass in sea is generally upright.
(3) Pyramid of energy is always upright.
(4) The pyramid of numbers in a grassland ecosystem is upright.
Solution: Correct Answer: (2) Pyramid of biomass in sea is generally upright.
Explanation:
(1) Pyramid of biomass in the sea is generally inverted. - In aquatic ecosystems, phytoplankton (producers) have less biomass than the zooplankton (consumers) at any given time. This is because phytoplankton reproduce rapidly and are consumed quickly.
(2) Pyramid of biomass in the sea is generally upright. - Incorrect, as the pyramid of biomass in marine ecosystems is inverted, not upright.
(3) Pyramid of energy is always upright. - Energy flows in one direction and is lost as heat at each trophic level. Hence, the energy pyramid is always upright.
(4) The pyramid of numbers in a grassland ecosystem is upright. - In grasslands, producers (grasses) are abundant, followed by herbivores (e.g., rabbits, deer) and then carnivores (e.g., foxes, snakes, hawks), making the pyramid of numbers upright.
Q-10. In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct?
(1) There is no relationship between Gross primary productivity and Net primary productivity.
(2) Gross primary productivity is always less than net primary productivity.
(3) Gross primary productivity is always more than net primary productivity.
(4) Gross primary productivity and Net primary productivity are one and the same.
Solution: Correct Answer: (3) Gross primary productivity is always more than net primary productivity.
Explanation:
The relationship between GPP and NPP:
NPP=GPP-RESPIRATION(R)
Since some energy is always used for respiration, NPP is always less than GPP.
Q-11. Which of the following is not an attribute of a population?
(1) Species interaction
(2) Sex ratio
(3) Natality
(4) Mortality
Solution: Correct Answer: (1) Species interaction
Explanation: Species interaction (e.g., predation, competition, mutualism, parasitism) occurs between different species and is a concept of community ecology, not population ecology. A population refers to only one species, so interspecies interactions are not considered its attribute.
Q-12. In the equation GPP - R = NPP represents :-
(1) Radiant energy
(2) Retardation factor
(3) Environment factor
(4) Respiration losses
Solution: Correct Answer: (4) Respiration losses
Explanation:
The given equation represents the relationship between Gross Primary Productivity (GPP) and Net Primary Productivity (NPP):
GPP−R=NPP
where R represents respiration losses by plants.
Q-13. Which one of the following is not included under in-situ conservation ?
(1) Wild-life sanctuary
(2) Botanical garden
(3) Biosphere reserve
(4) National park
Solution: Correct Answer: (2) Botanical garden
Explanation: In-situ conservation refers to the protection of species in their natural habitat. It involves conserving ecosystems and natural habitats where the species naturally exist. Botanical gardens are ex-situ conservation sites, where plants are grown outside their natural habitat for research, education, and conservation.
Q-14. Cryo preservation technique is used for :
(1) Protection of environment
(2) Protection of Biodiversity hotspots.
(3) Preservation of gametes in viable and fertile condition for a long period
(4) In-situ conservation
Solution: Correct Answer: (3) Preservation of gametes in viable and fertile condition for a long period
Explanation: Cryopreservation is a technique used to store biological material at extremely low temperatures (-196°C using liquid nitrogen) to preserve cells, tissues, and genetic material for a long time.
Q-15. Match List-I with List-II :
(1) A-I, B-IV, C-III, D-II
(2) A-IV, B-I, C-II, D -III
(3) A-III, B-I, C-II, D-IV
(4) A-II, B-IV, C-III, D-I
Solution: Correct Answer: (2) A-IV, B-I, C-II, D -III
(Session 2025 - 26)