NEET BotanyUpdated 19 Oct 2026

Organisms and Populations: NEET PYQs and weightage

Organisms and Populations 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 10 of 21 Botany chapters.

Take the 25-question Organisms and Populations test Key facts ↓All NEET Botany chapters

4.7/100 Weight in Botany

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

37 NEET PYQs

304 Practice questions

298 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.

Organisms and Populations: 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.

Levels of organisation in ecology
Ecology studies four levels of organisation: organisms, populations, communities and biomes.
Asked as: Which is NOT one of the four levels ecology deals with (e.g. ecosystem, cell)?
Per capita birth and death rates
$birth rate = \frac{8}{20} = 0.4 (20 lotus, 8 new)$
$death rate = \frac{4}{40} = 0.1 (4 deaths among 40 fruitflies)$
Population rates are per capita.
Asked as: Calculate the birth or death rate from given numbers.
Population attributes and age pyramids
Birth rate, death rate, sex ratio and age distribution belong to a population, not an individual. The shape of the age pyramid shows a growing, stable or declining population.
Asked as: Which attribute does an individual lack? / Identify the pyramid type.
Measuring population density
Density ( $N$ ) can be measured as per cent cover or biomass when counting misleads (one banyan vs 200 Parthenium). The tiger census uses pug marks and fecal pellets.
Asked as: Best measure of density for a banyan or a bacterial culture? / What is a tiger census based on?
Population change equation
$N_{t + 1} = N_{t} + [(B + I) - (D + E)]$
Births and deaths normally matter most. Immigration matters most when a new habitat is being colonised.
Asked as: Which factor dominates growth in a newly colonised habitat?
Exponential growth
$\frac{d N}{d t} = r N$
$N_{t} = N_{0} e^{r t} (integral form)$
It gives a J-shaped curve when resources are unlimited.
Asked as: J-shaped curve = which model / which resource condition?
Intrinsic rate of natural increase
$r$ is the intrinsic rate of natural increase: Norway rat $0.015$ , flour beetle $0.12$ , India in 1981 $0.0205$ .
Asked as: Match the organism with its $r$ value.
Logistic (Verhulst-Pearl) growth
$\frac{d N}{d t} = r N (\frac{K - N}{K})$
The sigmoid curve runs lag $\to$ acceleration $\to$ deceleration $\to$ asymptote at $K$ (carrying capacity). It is the more realistic model.
Asked as: Sequence of phases / what the asymptote represents.
Life history variation
Pacific salmon and bamboo breed only once. Oysters and pelagic fishes produce many small offspring, while birds and mammals produce few large ones.
Asked as: Which organism breeds only once in its lifetime?
Interaction signs
Interaction signs: mutualism $+ / +$ , competition $- / -$ , predation and parasitism $+ / -$ , commensalism $+ /0$ , amensalism $- /0$ .
Asked as: Match each interaction with its sign pair.
Predation: biological control and diversity
Prickly pear cactus (Australia, 1920s) was controlled by a cactus-feeding moth. Removing the starfish Pisaster made more than $10$ invertebrate species extinct within a year.
Asked as: Principle behind biological control / role of a predator in keeping species diversity.
Defences against predation
Monarch butterfly is distasteful to birds because of a chemical it takes in as a caterpillar from a poisonous weed. Calotropis makes cardiac glycosides. Acacia and Cactus defend with thorns. About $25%$ of insects are phytophagous.
Asked as: Which plant makes cardiac glycosides? / How does the Monarch get its chemical?
Competition examples
Competition can occur between unrelated species: flamingoes and fishes share zooplankton in South American lakes. Goats drove the Abingdon tortoise extinct within a decade. Connell showed Balanus excludes Chathamalus on the coast of Scotland.
Asked as: Example of competition between unrelated species / of competitive release.
Gause's Competitive Exclusion Principle
Two closely related species competing for the same limiting resource cannot co-exist indefinitely. Resource partitioning allows co-existence, as in MacArthur's five warbler species on one tree.
Asked as: Which mechanism let MacArthur's warblers co-exist?
Parasitism
The human liver fluke needs two intermediate hosts, a snail and a fish. Cuscuta has lost its chlorophyll and leaves. The cuckoo (koel) lays its eggs in the crow's nest (brood parasitism).
Asked as: Intermediate hosts of the liver fluke / an example of brood parasitism.
Commensalism and mutualism
Commensalism: orchid epiphyte on mango, barnacles on a whale, cattle egret with cattle, clown fish with sea anemone. Mutualism: lichens, mycorrhizae, fig–wasp (one-to-one) and Ophrys, which uses sexual deceit (pseudocopulation by a male bee).
Asked as: Orchid on a mango branch is which interaction? / How does Ophrys get pollinated?

Trap

Clown fish–sea anemone and orchid–mango are commensalism in NCERT, not mutualism or parasitism. The anemone and the mango tree get no benefit and suffer no harm.

How does NEET ask Organisms and Populations?

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 PYQPopulation Growth Models

Try right here · No sign-in

In the exponential growth equation N

_{t}

= N

_{0}

^{r t}

, e represents

Answer key (A) & worked solution

Correct answer: Option A

The integral form of the exponential growth equation as N

_{t}

= N

_{0}

^{r t}

where Nt = Population density after time t, N

_{0}

= Population density at time zero, r = intrinsic rate of natural increase, e = the base of natural logarithms.

Q2BotanyNEET UG PYQPopulation Interactions

A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is

AEctoparasitism

BSymbiosis

CCommensalism

DAmensalism

Answer key (C) & worked solution

Correct answer: Option C

The association between the sea anemone and hermit crab is commensalism. In such interaction, one species is benefitted while the other is neither harmed nor benefitted.Symbiosis- In this, both the organisms get the benefit. Example- Lichens (Algae and fungal association).Amensalism- In this, one organism is harmed and the other is unaffected. For example- Penicillin production from Penicillium notatum against Staphylococci bacteria.

Ectoparasitism- In this, one organism gets the benefit and the other is harmed. Example- Lice on humans.

Q3BotanyNEET UG PYQPopulation Interactions

Given below are two statements: Statement I: Gause’s ‘Competitive Exclusion Principle’ states that two closely related species competing for the same resources cannot co-exist indefinitely, and the competitively inferior one will be eliminated eventually. Statement II: In general, carnivores are more adversely affected by competition than herbivores. In the light of the above statements, choose the correct answer from the options given below:

ABoth Statement I and Statement II are false.

BStatement I is correct, but Statement II is false.

CStatement I is incorrect, but Statement II is true.

DBoth Statement I and Statement II are true.

Answer key (B) & worked solution

Correct answer: Option B

Statement II: In general, herbivores are more adversely affected by competition than carnivores.

Q4BotanyNEET UG PYQPopulation Interactions

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

AIt helps in maintaining species diversity in a community

BIt might lead to extinction of a species

CBoth the interacting species are negatively impacted

DIt is necessitated by nature to maintain the ecological balance

Answer key (C) & worked solution

Correct answer: Option C

In predation, the predator is benefitted whereas the prey population is negatively impacted since they are preyed on by the predator.

Q5BotanyNEET UG PYQPopulation Growth Models

When does the growth rate of a population following the logistic model equal zero? The logistic model is given as DN/dt = rN(1 – N/K)

AWhen N/K is exactly one

BWhen N nears the carrying capacity of the habitat

CWhen N/K equals zero

DWhen death rate is greater than birth rate

Answer key (A) & worked solution

Correct answer: Option A

Logistic growth of a population size occurs when resources are limited. The formula we use to calculate logistic growth adds the carrying capacity as a moderating force in the growth rate. The logistic model is given as dN/dt = rN(1-N/K). When the value of N/K is one, then, dN/dt = rN(1-N/K) dN/dt = rN(1-1) dN/dt = rN(0) dN/dt = 0 (zero) So, the growth rate of the population will be equal to zero, when the value of N/K is equal to one.

Q6BotanyNEET UG PYQPopulation Interactions

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:

ABoth A and R are correct but R is not the correct explanation of A

BA is correct but R is not correct

CA is not correct but R is correct

DBoth A and R are correct and R is the correct explanation of A

Answer key (D) & worked solution

Correct answer: Option D

The logistic growth model of populations is considered more realistic than the exponential growth model because resources are limited/finite in nature.

Q7BotanyNEET UG PYQPopulation Interactions

Pinus seed cannot germinate and establish without fungal association. This is because

AIt has obligate association with mycorrhizae

BIt have very hard seed coat

CIts seeds contain inhibitors that prevent germination

DIts embryo is immature

Answer key (A) & worked solution

Correct answer: Option A

Fungus associated with roots of Pinus increases minerals & water absorption for the plant by increasing surface area and in turn, fungus gets food from the plant, this association is called mycorrhizae. Therefore, the mycorrhizal association is obligatory for Pinus seed germination.

Q8BotanyNEET UG PYQPopulation Interactions

Gause’s principle of competitive exclusion states that

AMore abundant species will exclude the less abundant species through competition

BCompetition for the same resources excludes species having different food preferences

CNo two species can occupy the same niche indefinitely for the same limiting resources

DLarger organisms exclude smaller ones through competition

Answer key (C) & worked solution

Correct answer: Option C

In ecology, the competitive exclusion principle, sometimes referred to as Gause's law of competitive exclusion or just Gause's law states that two species competing for the same resource cannot coexist at constant population values if other ecological factors remain constant. When two competing life forms attempt to occupy the same niche, only one outcome is possible that is one life form will drive out the other.

Which topics in Organisms and Populations carry the most questions?

All 9 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
Population Interactions	19	107
Population Growth Models	7	43
Population and Population Attributes	6	44
Organisms and Environment	2	28
Major Abiotic Factors	1	32
Response to Abiotic Factors	1	28
Adaptations	1	17
Life History Variations	0	3
Miscellaneous Examples	0	2

Why does Organisms and Populations show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Organisms and Populations, 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 Organisms and Populations?

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 Organisms and Populations test

Chapters either side of Organisms and Populations by weight

Biodiversity and Its Conservation Weight 5.3/100 Ecosystem Weight 4.7/100 Anatomy of Flowering Plants Weight 4.5/100 Photosynthesis in Higher Plants Weight 4.3/100

Organisms and Populations: NEET PYQs and weightage

Organisms and Populations: key facts for NEET

Levels of organisation in ecology

Per capita birth and death rates

Population attributes and age pyramids

Measuring population density

Population change equation

Exponential growth

Intrinsic rate of natural increase

Logistic (Verhulst-Pearl) growth

Life history variation

Interaction signs

Predation: biological control and diversity

Defences against predation

Competition examples

Gause's Competitive Exclusion Principle

Parasitism

Commensalism and mutualism

How does NEET ask Organisms and Populations?

Which topics in Organisms and Populations carry the most questions?

Why does Organisms and Populations show "–" until you answer 3 questions?

What happens when you test Organisms and Populations?

Chapters either side of Organisms and Populations by weight