NEET BotanyUpdated 19 Oct 2026

Ecosystem: NEET PYQs and weightage

Ecosystem carries 4.7 of 100 Botany marks in NEET by past-paper share: 37 of the 793 tagged NEET Botany PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 9 of 21 Botany chapters.

Removed from NEET in this chapter: Succession, Biodgeochemical cycles. Still in NCERT and school exams, not asked in NEET now.

Take the 25-question Ecosystem test Key facts ↓All NEET Botany chapters

4.7/100 Weight in Botany

Exam importance (4/5, by past-paper share)

37 NEET PYQs

393 Practice questions

275 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Botany PYQs in the bank (37 of 793), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Ecosystem: key facts for NEET

16 facts the paper keeps asking, each with how it is asked. Copy it onto one page of your notebook: that page is this chapter's handbook.

Stratification
Stratification is the vertical distribution of species at different levels: trees form the top layer of a forest, shrubs the second, and herbs and grasses the bottom.
Asked as: "Species composition and ___ are the two main structural features of an ecosystem"
Functional aspects of an ecosystem
An ecosystem works as a unit through $4$ functional aspects: productivity, decomposition, energy flow and nutrient cycling.
Asked as: "Which of these is NOT a functional aspect of an ecosystem?"
Pond ecosystem components
In a pond, producers are phytoplankton, some algae and floating, submerged and marginal plants. Consumers are zooplankton, plus free-swimming and bottom-dwelling forms. Decomposers (fungi, bacteria, flagellates) are most abundant at the pond bottom.
Asked as: "The second trophic level in a lake is ___" (zooplankton)
Net primary productivity
$GPP - R = NPP$
NPP is the biomass available to heterotrophs (herbivores and decomposers). Productivity is a rate, in $g m^{- 2} y r^{- 1}$ or $kcal m^{- 2} y r^{- 1}$ .
Asked as: Given GPP and respiration, find NPP; or "productivity is expressed as ___"
Secondary productivity
Secondary productivity is the rate of formation of new organic matter by consumers.
Asked as: Match primary and secondary productivity to producers and consumers
Biosphere and ocean NPP
Annual NPP of the whole biosphere is about $170$ billion tons (dry weight). Oceans give only $55$ billion tons even though they cover about $70%$ of the surface.
Asked as: "Ocean productivity is low despite its area" assertion-reason
Steps of decomposition
Decomposition has $5$ steps: fragmentation (by detritivores, e.g. earthworm), leaching, catabolism (bacterial and fungal enzymes), humification and mineralisation.
Asked as: Match each step to its description; "leaching moves water-soluble nutrients down into the soil as unavailable salts"
Humus
Humus is dark, amorphous and colloidal. It resists microbial action, decomposes extremely slowly, and serves as a reservoir of nutrients. Mineralisation releases inorganic nutrients from it.
Asked as: "Which property of humus makes it a nutrient reservoir?"
Factors affecting decomposition
Decomposition is slow when detritus is rich in lignin and chitin, and fast when it is rich in nitrogen and sugars. Warm, moist conditions favour it; low temperature and anaerobiosis inhibit it.
Asked as: "Decomposition will be slowest when detritus is rich in ___"
Solar energy and PAR
The sun is the only energy source for all ecosystems except the deep-sea hydrothermal ecosystem. PAR is less than $50%$ of incident solar radiation, and plants capture only $2 - 10%$ of PAR.
Asked as: Percentage of PAR captured by plants; the one ecosystem not run on solar energy
Grazing and detritus food chains
In aquatic ecosystems, the grazing food chain (GFC) is the major path of energy flow. In terrestrial ecosystems, a much larger share of energy flows through the detritus food chain (DFC). DFC decomposers (mainly fungi and bacteria) are saprotrophs.
Asked as: "In a terrestrial ecosystem, most energy flows through ___"
10 per cent law
$10$ per cent law: only about $10%$ of energy passes from one trophic level to the next. This is why the GFC has few trophic levels.
Asked as: Producers have $10, 000 J$ ; how much energy reaches the secondary consumer? ( $100 J$ )
Standing crop
Standing crop is the mass (biomass) or number of living organisms per unit area at a trophic level at a given time. Dry weight is the more accurate measure of biomass.
Asked as: "Standing crop of a trophic level is measured as ___"
Trophic level
A trophic level is a functional level, not a species. A sparrow is a primary consumer when it eats seeds and a secondary consumer when it eats insects.
Asked as: "An organism occupying more than one trophic level" example
Pyramids of numbers and biomass
Pyramid of numbers in a grassland: about $6$ million plants support only $3$ top carnivores. Pyramid of numbers on a single tree with insects is inverted. Pyramid of biomass in the sea is generally inverted, because a small standing crop of phytoplankton supports a larger one of zooplankton or fish.
Asked as: "In an ecosystem dominated by trees, the pyramid of numbers is ___"
Nutrient cycles and limits of pyramids
Nutrient cycles are of $2$ types. Gaseous cycles (carbon) have the atmosphere or hydrosphere as reservoir. Sedimentary cycles (phosphorus) have Earth's crust as reservoir. Ecological pyramids give saprophytes no place and do not account for food webs.
Asked as: "Reservoir of the phosphorus cycle is ___"; limitations of ecological pyramids

Trap

Pyramids of numbers and biomass can be inverted (tree with insects; biomass in the sea). The pyramid of energy is always upright and can never be inverted, because some energy is lost as heat at every step.

How does NEET ask Ecosystem?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1BotanyNEET UG PYQTrophic Levels

Try right here · No sign-in

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

Answer key (C) & worked solution

Correct answer: Option C

Column IColumn II(a) Fourth trophic level(ii) Vulture(b) Second trophic level(iii) Rabbit(c) First trophic level(iv) Grass(d) Third trophic level(i) Crow

Q2BotanyNEET UG PYQSuccession

Match the following and select the correct option: Column IColumn IIAEarthworm(i)Pioneer speciesBSuccession(ii)DetritivoreCEcosystem service(iii)NatalityDPopulation growth(iv)Pollination

AA – (i), B – (ii), C – (iii), D – (iv)

BA – (iv), B – (i), C – (iii), D – (ii)

CA – (iii), B – (ii), C – (iv), D – (i)

DA – (ii), B – (i), C – (iv), D – (iii)

Answer key (D) & worked solution

Correct answer: Option D

Detritivores are heterotrophs that obtain nutrients by consuming detritus or decomposing plant and animal parts as well as faeces. Earthworms are a detrivore. In succession, pioneer species like lichen, algae, and fungi, as well as other abiotic factors like wind and water start to 'normalize' the habitat. Pollination is a type of ecosystem service which enhances the service provided by insects/birds through behavioral interaction. Natality is the crude birth rate or specific birth rate and is the greatest influence on a population's increase.

Q3BotanyNEET UG PYQBiodgeochemical cycles

In which of the following, both pairs have the correct combination?

AGaseous nutrient cycle, Sedimentary nutrient cycle - Carbon and nitrogen, Sulphur and phosphorus.

BGaseous nutrient cycle, Sedimentary nutrient cycle - Carbon and sulphur, Nitrogen and phosphorus.

CGaseous nutrient cycle, Sedimentary nutrient cycle - Nitrogen and sulphur, Carbon and phosphorus.

DGaseous nutrient cycle, Sedimentary nutrient cycle - Sulphur and phosphorus, Carbon and nitrogen.

Answer key (A) & worked solution

Correct answer: Option A

In a gaseous type of nutrient cycle, the reservoir is located either in the atmosphere or the hydrosphere. Hence, carbon and nitrogen cycles are gaseous nutrient cycles. In a sedimentary type of nutrient cycle, the reservoir exists in earth’s crust. Hence, sulphur and phosphorus are sedimentary nutrient cycles.

Q4BotanyNEET UG PYQFood Chain and Food Web

Increase in concentration of the toxicant at successive trophic levels is known as:

ABiomagnification

BBiodeterioration

CBiotransformation

DBiogeochemical cycling

Answer key (A) & worked solution

Correct answer: Option A

Biomagnification refers to an increase in concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level.

Q5BotanyNEET UG PYQEcosystems - Structure and Functions

Which one of the following is a characteristic feature of the cropland ecosystem?

AAbsence of soil organisms

BLeast genetic diversity

CAbsence of weeds

DEcological succession

Answer key (B) & worked solution

Correct answer: Option B

Least genetic diversity is a characteristic feature of cropland ecosystems. A crop land ecosystem will have a major crop cultivated in a given area. It shows that the diversity in that particular area will be least. Whereas it is the opposite when forest ecosystems are considered. This is manmade ecosystem. Man has been doing his best in modifying the croplands to get maximum benefit out of them. A cropland ecosystem may be illustrated by crops like wheat, maize, rice, sugarcane etc.

Q6BotanyNEET UG PYQProductivity of Ecosystem

In the equation GPP - R = NPP, R represents

AEnvironment factor

BRespiration losses

CRadiant energy

DRetardation factor

Answer key (B) & worked solution

Correct answer: Option B

The gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilized by plants in respiration. Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP). GPP – R = NPP. Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores and decomposers).

Q7BotanyNEET UG PYQProductivity of Ecosystem

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

AGross primary productivity and Net primary productivity are one and same

BThere is no relationship between Gross primary productivity and Net primary productivity

CGross primary productivity is always less than Net primary productivity

DGross primary productivity is always more than Net primary productivity

Answer key (D) & worked solution

Correct answer: Option D

The gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. Some of this organic matter is lost because of the respiration of plants. The remaining primary productivity is the net primary productivity, hence it is always less than gross primary productivity.

Q8BotanyNEET UG PYQEcosystems - Structure and Functions

The term ecosystem was coined by

AE.P. Odum

BA.G. Tansley

CE. Haeckel

DE. Warming

Answer key (B) & worked solution

Correct answer: Option B

Ecosystem is a segment of the biosphere consisting of a community of living beings and the abiotic or physical environment both interacting and exchanging materials between them. Word 'ecosystem' was first coined by Tansley in 1935 and previously the term 'biocoenosis' was used.

Which topics in Ecosystem carry the most questions?

All 10 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Decomposition	7	67
Productivity of Ecosystem	7	66
Ecosystems - Structure and Functions	6	55
Biodgeochemical cyclesNot in NEET now	5	19
Energy Flow	3	33
Trophic Levels	3	32
SuccessionNot in NEET now	3	27
Ecological Pyramids	2	52
Food Chain and Food Web	1	33
Miscellaneous Examples	0	9

Why does Ecosystem show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Ecosystem, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

How ViJEEta scores you

What happens when you test Ecosystem?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

Start the Ecosystem test

Chapters either side of Ecosystem by weight

Sexual Reproduction in Flowering plants Weight 6.4/100 Biodiversity and Its Conservation Weight 5.3/100 Organisms and Populations Weight 4.7/100 Anatomy of Flowering Plants Weight 4.5/100

Ecosystem: NEET PYQs and weightage

Ecosystem: key facts for NEET

Stratification

Functional aspects of an ecosystem

Pond ecosystem components

Net primary productivity

Secondary productivity

Biosphere and ocean NPP

Steps of decomposition

Humus

Factors affecting decomposition

Solar energy and PAR

Grazing and detritus food chains

10 per cent law

Standing crop

Trophic level

Pyramids of numbers and biomass

Nutrient cycles and limits of pyramids

How does NEET ask Ecosystem?

Which topics in Ecosystem carry the most questions?

Why does Ecosystem show "–" until you answer 3 questions?

What happens when you test Ecosystem?

Chapters either side of Ecosystem by weight