Every Ecology question CSIR-NET Life Sciences has set in its last 11 papers, sorted by topic, with 16 of them solved step by step. Answers follow NTA’s final answer keys.
Unit 10 of the CSIR-NET Life Sciences syllabus, Ecological Principles, covers the physical environment, habitat and niche, population and community ecology, species interactions, succession, ecosystem ecology, biogeography, applied ecology and conservation biology. We went through all 11 papers from February 2022 to June 2025 and pulled out every question from this unit. Only Plant Physiology carried more Part B and Part C questions over that period.
How much of the paper is Ecology?
Across the 11 papers, 129 of the 1,375 Part B and Part C questions (9.4%) came from Unit 10. That ranks it second of the 13 units. 85 of the 129 were 4-mark Part C questions.
| Paper | Part B | Part C | Total |
|---|---|---|---|
| June 2025 | 3 | 7 | 10 |
| December 2024, Shift 1 | 2 | 9 | 11 |
| December 2024, Shift 2 | 3 | 8 | 11 |
| June 2024, Shift 1 | 4 | 9 | 13 |
| June 2024, Shift 2 | 4 | 10 | 14 |
| December 2023, Shift 1 | 5 | 8 | 13 |
| December 2023, Shift 2 | 6 | 9 | 15 |
| June 2023, Shift 1 | 4 | 8 | 12 |
| June 2023, Shift 2 | 4 | 5 | 9 |
| February 2022, Shift 1 | 4 | 7 | 11 |
| February 2022, Shift 2 | 5 | 5 | 10 |
| All 11 papers | 44 | 85 | 129 |
Which Ecology topics come up most
Population Ecology and Community Ecology together account for 39% of the unit’s questions.
16 solved Ecology PYQs
One or two from each major subtopic, from different papers. Try each one before you open the solution.
A researcher captured 60 bivalves from a habitat on day 1 and tagged all of them. On day 2, she caught 40 bivalves out of which 20 were already tagged. She then estimated the population size of bivalves in the lake using this information. Which one of the options represents the percentage of the bivalve population that were marked on day 1?
- 110
- 250
- 360
- 420
Show answer and solution
By the Lincoln–Petersen method, population size N = (marked on day 1 × caught on day 2) ÷ recaptured = (60 × 40) ÷ 20 = 120. The 60 tagged bivalves are 60 ÷ 120 = 50% of the population. The same figure comes straight from the recapture: 20 of the 40 caught on day 2 carried tags.
An herbivore eats food that provides 1,000 kJ of energy of which, 500 kJ is lost in faeces, 350 kJ is used in cellular respiration, and 150 kJ is used for growth. The percent production efficiency of the herbivore is:
- 150
- 235
- 330
- 415
Show answer and solution
Production efficiency is production (growth) as a share of assimilated energy, not of energy eaten. Assimilation = ingestion − faeces = 1,000 − 500 = 500 kJ. Production = 150 kJ. So production efficiency = 150 ÷ 500 = 30%. (Assimilation efficiency would be 50%, and 15% is growth as a share of ingestion.)
The exponential growth equation dN/dt expresses the rate of population growth as the per capita rate of increase, r times population size N. This exponential model of population growth can be modified to produce a model in which population growth is sigmoidal by adding an element that slows growth, as population size approaches carrying capacity, K. If the per capita rate of increase rmax is the maximum per capita rate of increase, then select the correct option for the logistic equation for population growth.
- 1dN/dt = rmax (K − N)/K
- 2dN/dt = rmaxN (K − N)/K
- 3dN/dt = rmax N/K
- 4dN/dt = rmax K/N
Show answer and solution
Answer: (2) dN/dt = rmaxN (K − N)/K
The logistic equation multiplies exponential growth (rmaxN) by the fraction of carrying capacity still unused, (K − N)/K. Growth is close to exponential when N is small and falls to zero when N = K, which gives the S-shaped curve. Option 1 drops N, so it is not a growth rate.
Stable coexistence is possible in a classical two-species Lotka-Volterra competition model when
- 1intraspecific competition is stronger than interspecific competition.
- 2intraspecific competition is weaker than interspecific competition.
- 3inter- and intra-specific competitive effects are balanced.
- 4interspecific effects are offset by demographic stochasticity.
Show answer and solution
Answer: (1) intraspecific competition is stronger than interspecific competition.
In the Lotka–Volterra model the two species coexist stably only when each one limits its own growth more than it limits the other’s (α12 < K1/K2 and α21 < K2/K1). In other words, intraspecific competition is stronger than interspecific. If interspecific effects are stronger, one species excludes the other and which one wins depends on the starting numbers.
A positive association between absolute average individual fitness and population size over some finite interval is known as
- 1Allee effect
- 2Founder effect
- 3Rensch’s rule
- 4Bergmann’s rule
Show answer and solution
Answer: (1) Allee effect
The Allee effect is positive density dependence: below some population size, average individual fitness rises as the population grows, for example because mates are easier to find or group defence works. The founder effect is about genetic drift in a small colonising group. Rensch’s and Bergmann’s rules describe body-size patterns.
A desert annual plant with long-duration seed dormancy germinates only after heavy rainfall. What life history trait does this illustrate?
- 1Bet-hedging strategy
- 2K strategy
- 3Frequency-dependent reproduction
- 4Density-dependent reproduction
Show answer and solution
Answer: (1) Bet-hedging strategy
Long seed dormancy with germination only after heavy rain spreads the risk of failure across years. In any one year only some seeds germinate, so a single bad season cannot wipe out the whole generation. That is bet-hedging: giving up some average fitness to reduce its variance in an unpredictable environment.
Which one of the following terms is used for species that exploit the same resources in a similar manner?
- 1Guild
- 2Taxonomic order
- 3Community
- 4Assemblage
Show answer and solution
Answer: (1) Guild
A guild (Root, 1967) is a group of species that exploit the same class of resources in a similar way, whatever their taxonomy. Seed-eating birds and rodents can be in one guild. A community is all the interacting species in an area. An assemblage is a taxonomically defined subset of a community.
The relationship between species and area of distribution is given by the following equation: S = CAz where S is the number of species on an island or isolated patch, A is the area of the habitat, and C and Z are constants. The following are a set of statements pertaining to the value of ‘Z’:
- A. Z value is typically not greater than 0.4 across all ecosystem types.
- B. Z value is positively related to a species’ dispersal capability, with flying and wind-dispersed organisms having the highest values.
- C. Z value, which represents the slope in the relationship, declines with area, especially when large landmasses such as continents are considered.
- D. The Z value is the exponent in the power model and can be used to estimate the proportion of area required to represent a given proportion of species present in any land class.
Select the option that represents the combination of all correct statements.
- 1A and B
- 2A and D
- 3B and C
- 4C and D
Show answer and solution
Answer: (2) A and D
A is correct: z usually lies between about 0.15 and 0.35. D is correct: z is the exponent of the power law, so it is used to estimate how much area must be kept to retain a given fraction of species. B is wrong because good dispersers give lower z (isolated patches still receive them). C is wrong because z gets steeper, not shallower, at continental and inter-provincial scales.
Which one of the following options lists mechanisms that drive ecological succession?
- 1Only facilitation and tolerance
- 2Disturbance and tolerance
- 3Only tolerance and inhibition
- 4Facilitation, tolerance and inhibition
Show answer and solution
Answer: (4) Facilitation, tolerance and inhibition
Connell and Slatyer (1977) proposed three models of how early species affect later ones. In facilitation they make the site more suitable, in tolerance they have no effect, and in inhibition they make it harder. Disturbance starts or resets succession, but it is not one of the mechanisms that drive the replacement of species.
Which of the following biogeographic realms are divided by the Wallace Line?
- 1Indomalaya and Neotropical
- 2Indomalaya and Australasia
- 3Nearctic and Palearctic
- 4Palearctic and Afrotropical
Show answer and solution
Answer: (2) Indomalaya and Australasia
The Wallace Line runs between Bali and Lombok and between Borneo and Sulawesi. It separates the Indomalayan (Oriental) realm, with placental mammals such as tigers and primates, from Australasia, dominated by marsupials and monotremes. It follows deep-water channels that stayed open even when sea levels were low during the ice ages.
Which of the following describes ‘Empty Forest’?
- 1Absence of large trees
- 2Less species diversity due to natural reasons
- 3Habitat void of large mammals due to anthropogenic impacts
- 4Loss of habitat
Show answer and solution
Answer: (3) Habitat void of large mammals due to anthropogenic impacts
“The Empty Forest” is Kent Redford’s 1992 term for forests whose trees still stand, so they look intact from a satellite, but whose large mammals and birds have been hunted out. It is defaunation caused by people. The loss of seed dispersers and predators then changes the forest itself over time.
Select the correct combination of factors which drive the extinction vortex
- 1reduced population size, loss of genetic diversity, inbreeding
- 2emigration, fragmented habitat, inbreeding
- 3immigration, reduced population size, loss of genetic diversity
- 4catastrophic events, reduced population size, outbreeding
Show answer and solution
Answer: (1) reduced population size, loss of genetic diversity, inbreeding
In the extinction vortex, a small population loses genetic diversity through drift, which leads to inbreeding and inbreeding depression. That lowers survival and reproduction, so the population shrinks further and the cycle speeds up. Reduced population size, loss of genetic diversity and inbreeding are the three linked drivers. Immigration would slow the vortex.
As per Aichi Target 11 of the Convention on Biological Diversity, what percentage of geographical area was proposed to be protected for biodiversity conservation by the year 2020?
- 1Terrestrial and inland water 23%, coastal and marine areas 17%
- 2Terrestrial and inland water 23%, coastal and marine areas 10%
- 3Terrestrial and inland water 17%, coastal and marine areas 10%
- 4Terrestrial and inland water 17%, coastal and marine areas 7%
Show answer and solution
Answer: (3) Terrestrial and inland water 17%, coastal and marine areas 10%
Aichi Target 11, part of the CBD Strategic Plan 2011–2020, called for at least 17% of terrestrial and inland water areas and 10% of coastal and marine areas to be conserved in protected areas by 2020. Its successor, the Kunming–Montreal framework, raised both to 30% by 2030.
Which one of the following pollutants does NOT concentrate in organisms at higher trophic levels due to biomagnification?
- 1Mercury
- 2Phosphate
- 3Persistent Organic Pollutants (POPs)
- 4Selenium
Show answer and solution
Answer: (2) Phosphate
Biomagnification happens with substances that are persistent, fat-soluble and poorly excreted, so they build up at each trophic level: methylmercury, selenium and POPs such as DDT and PCBs. Phosphate is a water-soluble nutrient that organisms take up, use and excrete. It causes eutrophication, not biomagnification.
Which of the following constitute the largest reservoir of carbon in the global carbon cycle?
- 1The atmosphere
- 2The plant biomass on land
- 3Soils
- 4The ocean
Show answer and solution
Answer: (4) The ocean
Of the reservoirs listed, the ocean holds by far the most carbon, about 38,000 Gt, mostly as dissolved inorganic carbon in deep water. Soils hold roughly 1,500–2,400 Gt, the atmosphere about 870 Gt and land plants about 450–650 Gt. Sedimentary rocks hold more still, but they are not among the options.
Which one of the following gases is present in the stratosphere at a concentration higher than its concentration in troposphere?
- 1Nitrogen
- 2Oxygen
- 3Ozone
- 4Carbon dioxide
Show answer and solution
Answer: (3) Ozone
About 90% of atmospheric ozone sits in the stratosphere (the ozone layer, about 15–35 km up), where UV splits O2 and the free O atoms combine with O2 to form O3. Nitrogen and oxygen keep the same proportions through both layers, and CO2 is well mixed, slightly lower in the stratosphere.
All 129 Ecology questions, by subtopic
Each link opens the question on its full paper page. Press Show answer and solution there to see NTA’s final key and a worked solution.
Population Ecology (29 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q30 | B | In the classical metapopulation model as articulated by Richard Levins (1969, 1970), the metapopulation is considered to be a collection of… |
| Jun 2025, Q41 | B | For a given organism, which one of these life history attributes is associated with the broadest range of environmental tolerance? |
| Jun 2025, Q86 | C | A population of Indian wolf shows logistic growth. Let the carrying capacity (K) be 200 and intrinsic rate of increase, r = 0.05. What is… |
| Dec 2024 S1, Q113 | C | A parasitoid infects a host to complete its life cycle. Which of the following life-history traits typically characterizes this parasitoid… |
| Dec 2024 S2, Q28 | B | A researcher captured 60 bivalves from a habitat on day 1 and tagged all of them. On day 2, she caught 40 bivalves out of which 20 were… |
| Dec 2024 S2, Q55 | B | A desert annual plant with long-duration seed dormancy germinates only after heavy rainfall. What life history trait does this illustrate? |
| Dec 2024 S2, Q84 | C | Populations of two species (A and B) follow logistic growth. The parameter values for the logistic growth equation are given in the table… |
| Dec 2024 S2, Q102 | C | In the classical metapopulation model articulated by Richard Levins (1969, 1970), the metapopulation is considered to be a collection of… |
| Jun 2024 S1, Q22 | B | Which of these traits is NOT characteristic of r-selected tree species? |
| Jun 2024 S1, Q76 | C | In a line transect of length L and half-width w, designed for estimating the density of gaur (~ D=N/2Lw), N animals were counted. The… |
| Jun 2024 S1, Q85 | C | A student used the mark-recapture method to assess the population size of grasshopper in a field. The student was asked to repeat the… |
| Jun 2024 S1, Q120 | C | For a population that grows exponentially in the time interval (t, t+1), we have Nt+1 = R Nt, where N denotes population size and R denotes… |
| Jun 2024 S1, Q130 | C | Here is some data for a cohort of 400 individuals of a species whose abundance was tracked for 6 years (its maximum lifespan). For one-year… |
| Jun 2024 S2, Q119 | C | In a population with density-dependent effects on births and deaths due to intraspecific competition, the net recruitment curve is dome-shaped because |
| Jun 2024 S2, Q127 | C | The lines (A to D) in the graphs represent trait relationships that capture the allocations of different tree species to their present… |
| Jun 2024 S2, Q129 | C | The exponential growth equation dN/dt expresses the rate of population growth as the per capita rate of increase, r times population size… |
| Jun 2024 S2, Q135 | C | In the figure below, which of the curves that relate current reproductive effort with future reproductive value are likely to favor… |
| Dec 2023 S2, Q58 | B | What is the typical maximum sustainable yield for a fish population, given that its carrying capacity (K) is 20,000 and intrinsic growth… |
| Dec 2023 S2, Q128 | C | Some of the statements given below are related to species that show r– or k-selection strategies: Choose the option that contains all the… |
| Dec 2023 S2, Q129 | C | A researcher captured 45 fish from a lake on day 1, tagged and released them back. On day 2 the researcher caught 50 fish out from the same… |
| Dec 2023 S2, Q136 | C | The reproductive cycles of two populations (X and Y) of the silk cotton tree (Ceiba pentandra) were monitored for one year. A census was… |
| Jun 2023 S1, Q59 | B | A positive association between absolute average individual fitness and population size over some finite interval is known as |
| Jun 2023 S1, Q127 | C | Given below are a set of statements about metapopulation dynamics and habitat conservation: Which one of the following options represents… |
| Jun 2023 S1, Q128 | C | Ecologists examined the role of competition for below ground resources (water and nutrients) in the dispersion pattern of trees in the… |
| Jun 2023 S2, Q59 | B | A tree species has leaves that contain an allelochemical compound that leaches into the soil and prevents the growth of its own seedlings… |
| Jun 2023 S2, Q125 | C | The following is the life table of a natural population of a small annual succulent where ‘x’ is its life phase, ‘lx’ is its survivorship… |
| Jun 2023 S2, Q126 | C | Which of the following plots best depicts growth as per the logistic equation? |
| Feb 2022 S1, Q56 | B | The graph below shows the change in the size of four populations (A-D) over time. Which among the four populations (A, B, C, and D) would… |
| Feb 2022 S1, Q127 | C | Consider the following graphs for per capita growth rate (1/N)(dN/dt) as a function of population density (N). Which one of the plots… |
Community Ecology (21 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q127 | C | Given below are four niche-oriented models proposed to explain species-abundance distributions in ecological communities. Assuming a… |
| Dec 2024 S1, Q82 | C | Which one of the following statements is NOT part of the neutral paradigm in ecology? |
| Dec 2024 S1, Q108 | C | The table below gives the avian community composition of three communities (X, Y, Z), where ‘1’ indicates the presence of the species in… |
| Dec 2024 S1, Q126 | C | A student studying tree species diversity uses a large number of sampling quadrats (each of 1-hectare area) to cover >50% of the area of… |
| Dec 2024 S1, Q137 | C | Which one of the following is INCORRECT regarding Hill numbers (q), a family of diversity indices? |
| Dec 2024 S2, Q36 | B | The presence and abundance of a species in a local community is dependent on multiple processes. Which one of these processes is UNLIKELY… |
| Dec 2024 S2, Q95 | C | Which one of the following scenarios is likely to produce the highest beta diversity for tree species in a forested landscape? |
| Dec 2024 S2, Q115 | C | The figure below represents a bipartite network of species interactions between two trophic levels. Each link represents an interaction… |
| Dec 2024 S2, Q133 | C | The phylogeny given below depicts the evolutionary relationships and branch lengths of species found in three spider communities, X, Y, and… |
| Dec 2024 S2, Q144 | C | An ecologist calculates the Shannon-Wiener diversity index for an ecosystem with high species diversity. Which one of the following… |
| Jun 2024 S1, Q27 | B | A community of woody plants is being shaped by environmental filtering. What will be the likely local species pool of this community, if… |
| Jun 2024 S1, Q92 | C | An ecological community is more than just the sum of the attributes of the constituent species. Which one of the following options is NOT… |
| Jun 2024 S1, Q115 | C | Which of the following options represents the correct order of increasing biological organisation? |
| Jun 2024 S2, Q130 | C | In a quadrat sample for tree species in a plantation, 20 species were found in almost equal abundance. The Shannon’s index of diversity is… |
| Dec 2023 S1, Q126 | C | In a study comparing different plant communities (A to D) across a landscape, the following data were obtained: Which one of the following… |
| Dec 2023 S2, Q140 | C | Plotless sampling techniques have been applied by plant ecologists when rapid estimates of the density of plants in a large region are… |
| Jun 2023 S1, Q57 | B | Which one of the following terms is used for species that exploit the same resources in a similar manner? |
| Jun 2023 S1, Q125 | C | The relationship between species and area of distribution is given by the following equation: S = CAz where S is the number of species on… |
| Jun 2023 S1, Q129 | C | Four different plant communities that consisted of the same number of species were taken up for a species diversity study. The following… |
| Jun 2023 S2, Q129 | C | The number of individuals of different species in two communities P and Q is given below. Based on the given data, select the correct statement? |
| Feb 2022 S1, Q122 | C | The tables below show the bird species and their abundance in three habitats P, Q and R. Which one of the combinations below best… |
Ecosystem Ecology (21 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q114 | C | The following figure shows the decomposition of selected plant litter constituents. In the above, the correct identities of the symbols A… |
| Jun 2025, Q121 | C | The table below presents the energy transfer values for various activities exhibited by three herbivores inhabiting a grassland with a net… |
| Dec 2024 S1, Q77 | C | The following table shows forest floor litter pool and aboveground litterfall data for three forest types. Based on the provided… |
| Jun 2024 S1, Q129 | C | The given table shows the annual Net Primary Productivity (NPP), season length, and Leaf Area Index (LAI) for various ecosystems. Which one… |
| Dec 2023 S1, Q57 | B | Which one of the following correctly shows the total estimated biomass of the lifeforms on Earth given here, in increasing order? |
| Dec 2023 S1, Q59 | B | Which one of the following anthropogenic activities contributes the most nitrogen to the global nitrogen cycle? |
| Dec 2023 S1, Q60 | B | In which of the following ecosystems would the largest percentage of Net Primary Productivity (NPP) be taken up by the grazing food chain? |
| Dec 2023 S1, Q127 | C | Phosphorus is an important essential element for living organisms. Given below are a few fluxes of the global phosphorus cycle. Select the… |
| Dec 2023 S1, Q130 | C | Match the names of scientists (column X) with the ecosystem concepts (column Y) they are known for: |
| Dec 2023 S2, Q56 | B | An herbivore eats food that provides 1,000 kJ of energy of which, 500 kJ is lost in faeces, 350 kJ is used in cellular respiration, and 150… |
| Dec 2023 S2, Q57 | B | Which one of the following pollutants does NOT concentrate in organisms at higher trophic levels due to biomagnification? |
| Dec 2023 S2, Q125 | C | Nutrients are gained or lost by ecosystems in a variety of ways. These nutrients may accumulate in different organic or inorganic pools… |
| Dec 2023 S2, Q126 | C | Which one of the following graphs typically represents the change in C:N ratio over time in decomposing leaf litter in temperate forests? |
| Jun 2023 S1, Q119 | C | Which one of the following options correctly lists ecosystems of the world arranged according to the descending order of their average… |
| Jun 2023 S1, Q122 | C | Which one of the following statements pertaining to global ocean ecosystem productivity is NOT correct? |
| Jun 2023 S2, Q57 | B | Which one of the following curves correctly depicts the relationship of the NPP/GPP ratio with latitude? |
| Feb 2022 S1, Q57 | B | Consider the following ecosystems. Which one of the following options represents these ecosystems in an increasing order of their… |
| Feb 2022 S1, Q124 | C | The diagram below depicts energy flow within a single trophic level, where I=amount ingested, NA= amount not assimilated, R=respiration… |
| Feb 2022 S1, Q125 | C | The following graph shows the change in proportion of biomass in foliage (leaves), branch and stemwood (bole) for a tree species as a… |
| Feb 2022 S2, Q57 | B | Which of the following constitute the largest reservoir of carbon in the global carbon cycle? |
| Feb 2022 S2, Q125 | C | The largest reservoir of nitrogen in the global nitrogen cycle is the atmosphere. Options A-D below represent important pathways in the… |
Conservation Biology (18 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q58 | B | Which one of the following habitats harbors the critically endangered Great Indian Bustard (Ardeotis nigriceps)? |
| Jun 2025, Q83 | C | The Red List of the IUCN categorises species (Column X) under multiple threat levels (Column Y). Match the following species with their… |
| Dec 2024 S1, Q40 | B | Saara hardwickii, a spiny-tailed lizard, is a diurnal, ground-dwelling species currently known from the Indian subcontinent. It is endemic… |
| Dec 2024 S1, Q128 | C | A researcher uses taxon weighting and complementarity as criteria to prioritise communities for biodiversity conservation. The diagram… |
| Jun 2024 S1, Q62 | B | Which one of the following options includes all plants that are major non-native invaders of aquatic ecosystems in India? |
| Jun 2024 S2, Q70 | B | Which of the following describes ‘Empty Forest’? |
| Jun 2024 S2, Q71 | C | The statements given below indicate key characteristics of a geographical region. Which one of the following combinations represents the… |
| Dec 2023 S1, Q55 | B | Select the species that was thought to be extinct because of climate change and habitat loss, but was recently rediscovered in the year 2022. |
| Dec 2023 S2, Q53 | B | As per Aichi Target 11 of the Convention on Biological Diversity, what percentage of geographical area was proposed to be protected for… |
| Dec 2023 S2, Q55 | B | As per the ENVIS database, approximately how much of India’s landmass is designated under various categories of protected areas for… |
| Dec 2023 S2, Q59 | B | According to the latest IUCN Red List (2022), which one of the following groups has the highest percentage of assessed species that are… |
| Dec 2023 S2, Q130 | C | Western Ghats of India is considered as one of the global biodiversity hotspots because of some of the following characteristics: Which one… |
| Jun 2023 S1, Q58 | B | Invasive species, in general grow very well in a new area that they invade, and often outcompete native species. An explanation for the… |
| Jun 2023 S2, Q56 | B | Which one of the options given below is NOT desirable when setting up nature reserves in the tropics? |
| Jun 2023 S2, Q121 | C | Select the rare or endangered species which also have exceptionally low genetic variability, as documented by multi-locus molecular methods. |
| Feb 2022 S1, Q118 | C | The table given below lists the conservation areas and the major group of organisms that they are best known for. Which one of the… |
| Feb 2022 S2, Q53 | B | Select the correct combination of factors which drive the extinction vortex |
| Feb 2022 S2, Q126 | C | Fragmentation breaks up contiguous tracts of natural habitats into smaller patches. In a fragmented landscape where a previously large… |
Applied Ecology (12 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q78 | C | As per the 2020 FAO Global Forest Resources Assessment, the climatic domains ranked in descending order based on their proportion and… |
| Dec 2024 S1, Q52 | B | As per the India State of Forest Report 2021, the percentage cover of ‘very dense forests’ as a component of the country’s total geographical area is: |
| Jun 2024 S2, Q23 | B | Greenhouse Gas emissions are considered the primary driver of global warming through their influence on the radiative forcing of the… |
| Jun 2024 S2, Q26 | B | The proponents of sustainable development argue for a switch to a predominantly plant-based diet, in order to reduce the human footprint of… |
| Dec 2023 S1, Q121 | C | Selected human diseases and their vectors are listed below: Which one of the following options represents the correct match between column… |
| Dec 2023 S1, Q128 | C | The graph below depicts the net change in forest cover in four regions (A–D) between 1990 and 2020, according to the FAO report ‘The State… |
| Dec 2023 S1, Q140 | C | The figure below depicts the reflectance curves of different features found in an urban ecosystem. Which one of the options below correctly… |
| Jun 2023 S1, Q126 | C | The diagram below depicts the cumulative fossil CO2 emissions (y axis) of different continents from the years 1850-2020 (x axis). Select… |
| Feb 2022 S1, Q58 | B | Historical frequencies of fires in an area can be determined by |
| Feb 2022 S2, Q59 | B | The Covid-19 pandemic had a major impact on CO2 emissions due to the disruption of industrial activities caused by it. Which of the… |
| Feb 2022 S2, Q120 | C | Select the correct combination of species (column X) and the known cause of their population declines. |
| Feb 2022 S2, Q127 | C | In a high-altitude meadow region, it was observed that over the last five years 20 forb species flowered 2-3 weeks earlier than their… |
Biogeography (11 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2024 S1, Q104 | C | The table below lists selected bird species (Column X) and their possible habitats (Column Y). Which one of the following options… |
| Dec 2024 S2, Q125 | C | The following table shows a list of migratory birds coming to India (Column X) and the region from where they migrate (Column Y). Which one… |
| Jun 2024 S1, Q48 | B | Andaman and Nicobar archipelago are part of which biodiversity hotspots? |
| Jun 2024 S1, Q109 | C | Which one of the options below includes habitats that are ALL found in the Indian subcontinent? |
| Jun 2024 S2, Q36 | B | Which of the following biogeographic realms are divided by the Wallace Line? |
| Jun 2024 S2, Q85 | C | Given below are mammals and their location in India: Which one of the following options represents the correct match between the mammals… |
| Jun 2024 S2, Q101 | C | The table below represents a list of geographical regions and avian fauna. Which one of the following options represents the combination of… |
| Jun 2024 S2, Q128 | C | In the table given below, match the national parks with the mountain range in India where they are located. Which one of the following… |
| Dec 2023 S1, Q58 | B | Which one of the following options lists landmasses that were all a part of the ancient Gondwana supercontinent? |
| Feb 2022 S1, Q133 | C | A researcher working on island biogeography mapped how isolation-controlled immigration (I), and area-controlled extinction (E), will act… |
| Feb 2022 S2, Q58 | B | Select the correct statement from the options given below to complete the following. In the 1960s, experiments were conducted to test the… |
The Environment – Physical Factors (6 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2024 S2, Q105 | C | The following table presents soil formation processes (Column X) and climatic conditions in which they occur (Column Y). Which one of the… |
| Dec 2023 S1, Q124 | C | The following table lists habitat type (Column X) and geographic regions (Column Y) where they can be found: Which of the following options… |
| Dec 2023 S1, Q125 | C | Which one of the following statements about change in temperature with elevation is correct? |
| Feb 2022 S1, Q55 | B | Which one of the following gases is present in the stratosphere at a concentration higher than its concentration in troposphere? |
| Feb 2022 S2, Q55 | B | Which one of the following ecosystems is unique to India? |
| Feb 2022 S2, Q124 | C | The microclimate at the ground level is very important to plant life. Each curve (A-D) in the diagram below shows the temperature profiles… |
Ecological Succession (5 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q113 | C | In a successional chronosequence (30 – 400 years) on a sand dune, Ammophilia dune grass dominates the youngest dunes, the prairie bunch… |
| Dec 2024 S1, Q100 | C | Which statement about studies on succession is INCORRECT? |
| Jun 2023 S1, Q61 | B | Which one of the following statements is correct for a primary successional species? |
| Jun 2023 S2, Q58 | B | Which one of the following options lists mechanisms that drive ecological succession? |
| Feb 2022 S1, Q126 | C | The graphs given below show the possible behavior of two species over the course of succession. Possible effects observed during succession… |
Species Interactions (4 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2024 S1, Q101 | C | The following statements represent possible outcomes of competition between two species. Which one of the following options represents the… |
| Jun 2024 S2, Q102 | C | Stable coexistence is possible in a classical two-species Lotka-Volterra competition model when |
| Dec 2023 S2, Q133 | C | Competition between two species (A and B) can be represented as vector field graphs. Competition in its classic form can have four… |
| Jun 2023 S1, Q130 | C | A food chain involving Spartina (a plant), the marsh periwinkle snail, the blue crab and an unknown fungus was identified in a… |
Habitat & Niche (2 questions)
| Paper and question | Part | Question |
|---|---|---|
| Dec 2023 S2, Q127 | C | The table below lists terminologies (column X) and concepts (column Y) related to ecological niche. Which one of the following options… |
| Jun 2023 S2, Q128 | C | The figure below represents the fundamental and realised niche of two species. Which one of the following options correctly identifies the… |
PYQs for every CSIR-NET unit
How to revise Ecology with these questions
- Start with the two biggest subtopicsPopulation Ecology and Community Ecology are where most of the marks have been. Revise them first.
- Attempt before you readWork through a subtopic’s questions on paper, then check them against the answer keys.
- Find the repeatsThe same ideas keep coming back in new wording. When you get one wrong, look for its earlier version in the list above.
- Finish with a full paperTake a whole paper in live exam mode to practise choosing which Part C questions to attempt.
Keep going
<
p class=”lbq-src”>Source: CSIR-NET Life Sciences question papers and final answer keys, National Testing Agency, February 2022 to June 2025. Subtopic tags, difficulty ratings and solutions: Lesson Basket.
