Organisms and PopulationsNEET MCQs with solutions
Organisms and Populations covers how organisms adapt to their environment (thermoregulation, dormancy), population attributes (birth rate, death rate, age pyramids) and population growth models (exponential vs logistic). NEET tests the growth equations, carrying capacity, and species interactions (mutualism, competition, parasitism, predation, commensalism, amensalism).
- Class
- 12 Biology
- Free on this page
- 24 questions
- In the RankUp app
- 439 questions
- ELITE questions
- 236
- NCERT topics
- 7
Practise 24 questions
Tap an option to check it. Questions from every NCERT topic in this chapter, from easy to hard.
Q1Important PYQ Mixed Concepts
An organism enters a population from another geographical area and successfully establishes there. Which population attribute has directly increased because of this event?
Not quite — the answer is C.
Immigration means movement of individuals into a population from outside and directly increases population density. Natality also increases density but refers specifically to births within the population. Mortality and emigration both decrease population density.
Q2Important PYQ Mixed Concepts
An orchid grows epiphytically on a mango tree, obtaining support and light access, while the mango tree is neither significantly benefited nor harmed. Which interaction does this represent?
Not quite — the answer is D.
The orchid obtains support and better light access while the host tree is essentially unaffected, giving the +/0 relationship of commensalism. Parasitism would require the mango to be harmed. Mutualism requires both to benefit. Amensalism requires one species to be harmed with no effect on the other.
Q3Important PYQ Mixed Concepts
A population has abundant pre-reproductive individuals, a relatively narrow reproductive group and a small post-reproductive group. Which conclusion is most appropriate?
Not quite — the answer is B.
A broad pre-reproductive base indicates many individuals are yet to enter reproductive age, indicating an expanding population. A declining population has a narrower pre-reproductive base relative to older groups. Reaching carrying capacity or zero growth is not directly indicated by age-group proportions alone.
Q4Population Interactions
Which ecological interaction benefits one species while the other is neither harmed nor benefited?
Not quite — the answer is B.
In commensalism, one species benefits and the other is completely unaffected — neither harmed nor helped. Mutualism benefits both; parasitism harms the host; amensalism harms one species.
Q5Population Interactions
Which interaction involves one species deriving nutrition from another, harming but not immediately killing it?
Not quite — the answer is C.
Parasitism is defined by one organism (parasite) living on/in a host, deriving nutrients while harming it without immediate killing. Predation involves immediate killing of prey.
Q6Population Interactions
Which type of mutualism involves partners that cannot survive independently without each other?
Not quite — the answer is D.
In obligate mutualism, both species are entirely dependent on each other — e.g., lichens (alga + fungus). Facultative mutualism benefits both but neither partner is fully dependent.
Q7Organism and Its Environment
Which term refers to the specific place where an organism lives and performs its functions?
Not quite — the answer is A.
Habitat is the physical place where an organism lives and carries out its life activities. Niche describes the functional role of the organism within that habitat, not its location.
Q8Organism and Its Environment
Which abiotic factor most directly affects enzyme kinetics and metabolic activity in organisms?
Not quite — the answer is B.
Temperature directly controls the rate of enzymatic reactions by affecting molecular kinetic energy and enzyme conformation. Light drives photosynthesis but does not directly regulate enzyme kinetics across all metabolic pathways.
Q9Organism and Its Environment
Organisms capable of tolerating a wide range of temperature variations are called:
Not quite — the answer is C.
Eurythermal organisms survive across a wide temperature range; stenothermal organisms tolerate only a narrow range. Thermophilic organisms specifically thrive at high temperatures and are not a tolerance-range category.
Q10Mixed Revision
An epiphytic plant grows on the branch of a mango tree without obtaining nutrients from the tree. Which ecological interaction is represented?
Not quite — the answer is C.
The epiphyte obtains support and better access to light, while the mango tree is not significantly affected. Therefore the interaction is +/0, i.e. commensalism. Predation and parasitism both harm one partner. Mutualism benefits both partners.
Q11Mixed Revision
Which example represents mutualism rather than commensalism?
Not quite — the answer is A.
Lichen represents mutualism because both the alga and the fungus benefit from the association. Orchids on trees, cattle egret near grazing cattle, and barnacles on whales are standard examples of commensalism in which one partner benefits while the other is not significantly affected.
Q12Mixed Revision
A population has a broad-based age pyramid with the pre-reproductive group much larger than the reproductive and post-reproductive groups. What does this indicate?
Not quite — the answer is A.
A broad base means a high proportion of young pre-reproductive individuals. As these individuals mature and enter the reproductive group, the population has the potential to expand rapidly. A stable population shows equal proportions across groups. A declining population has a narrow base.
415 more questions on this chapter are waiting in the app
Every one with a detailed explanation, plus flashcards and chapter tests.
Get RankUp on Google PlayQ13Grand Test
An epiphytic plant grows on the branch of a mango tree and obtains only physical support from it while the mango tree is not significantly affected. Which interaction is represented?
Not quite — the answer is D.
The epiphyte gains support and better access to light while the host remains essentially unaffected giving a plus-zero interaction. This is commensalism not parasitism because the host is not harmed and not mutualism because only one partner benefits.
Q14Grand Test
Which equation correctly represents Verhulst-Pearl logistic growth for a population with carrying capacity K?
Not quite — the answer is B.
Logistic growth incorporates environmental resistance through the factor (K minus N) divided by K. When N approaches K this factor approaches zero and population growth levels off. The exponential equation rN lacks any carrying capacity term and allows unlimited growth.
Q15Grand Test
Which pair is correctly associated with the ecological interaction represented?
Not quite — the answer is D.
Fig-wasp is a classic mutualistic association in which the fig provides a site and resource for the wasp while the wasp pollinates the fig. Mycorrhiza is mutualism not parasitism. Cuscuta is a parasite not mutualistic. Lichen is mutualism not competition.
Q16Population Attributes
Which characteristic of a population cannot be applied meaningfully to an individual organism?
Not quite — the answer is A.
Natality (birth rate) is a property of a group and has no meaning for a single individual; an individual cannot have a birth rate. Growth, respiration, and excretion are all properties of individual organisms.
Q17Population Attributes
Population density is defined as:
Not quite — the answer is B.
Population density measures the number of individuals of a species per unit area (terrestrial) or volume (aquatic). Total species count describes species richness, not density of one population.
Q18Population Attributes
Which formula correctly represents change in population size over time?
Not quite — the answer is C.
Population size is determined by four processes: births (B) and immigration (I) add individuals; deaths (D) and emigration (E) remove them — giving N = (B + I) − (D + E). Option D incorrectly adds all four, which would always inflate population size.
Q19Population Growth
In population ecology, the symbol 'r' represents:
Not quite — the answer is A.
'r' is the intrinsic rate of natural increase — per capita growth rate under ideal, unlimited conditions. It is not carrying capacity (K) or environmental resistance, which oppose growth.
Q20Population Growth
Which equation correctly represents exponential population growth under unlimited resources?
Not quite — the answer is B.
Exponential growth is expressed as dN/dt = rN, where growth is proportional to population size with no resource limitation. Option A is the logistic equation, which includes carrying capacity K.
Q21Population Growth
The J-shaped population growth curve corresponds to which growth model?
Not quite — the answer is C.
Exponential growth under unlimited resources produces a J-shaped curve with continuously accelerating growth. Logistic growth produces an S-shaped (sigmoid) curve, not J-shaped.
Q22Organism and Its Environment
Animals that maintain relatively constant internal body temperature independent of environmental temperature are termed:
Not quite — the answer is D.
Endotherms generate metabolic heat to maintain a stable core temperature regardless of external conditions. Ectotherms and poikilotherms depend on environmental heat sources and show variable body temperatures.
Q23Organism and Its Environment
Which adaptation enables desert mammals such as kangaroo rats to conserve water efficiently?
Not quite — the answer is A.
Kangaroo rats produce highly concentrated urine and dry feces, minimizing water loss in arid habitats. Sweating and high evaporation would cause fatal dehydration in desert conditions.
Q24Organism and Its Environment
Which environmental signal mainly controls photoperiodic responses like flowering in plants?
Not quite — the answer is B.
Photoperiodism is the response to the relative duration of light and dark periods (day length), not total light intensity or temperature. Soil nutrients and minerals have no role in triggering photoperiodic responses.
ELITE question · AIR under 50 level
This chapter has 236 ELITE questions for students aiming at the very top. They are only in the app.
Unlock ELITE questions in the appKey Ecology Concepts
Quick revision: most questions in this chapter test these facts.
| Concept | Key Fact |
|---|---|
| Exponential growth | dN/dt = rN; J-shaped curve; unlimited resources |
| Logistic growth | dN/dt = rN(K-N)/K; S-shaped curve; K = carrying capacity |
| Mutualism | Both benefit (e.g. lichens: fungus + alga; mycorrhiza: fungus + plant roots) |
| Parasitism | +/– interaction; parasite benefits, host harmed (e.g. Cuscuta on hedge plants) |
| Competition | –/– interaction; competitive exclusion (Gause's principle) |
| Adaptations | Allen's rule (shorter extremities in cold); Bergmann's rule (larger body in cold) |
What the app covers in this chapter
439 questions in total, each with a detailed explanation.
| Important PYQ Mixed Concepts | 100 |
| Population Interactions | 80 |
| Organism and Its Environment | 60 |
| Mixed Revision | 60 |
| Grand Test | 59 |
| Population Attributes | 40 |
| Population Growth | 40 |
Questions students ask
Is Organisms and Populations important for NEET?
Yes — population growth equations, species interactions and ecological adaptations are tested regularly. The growth models (exponential vs logistic) and their equations are especially important.
Which topics should I revise first?
Master the two growth equations with their curves, carrying capacity concept, all six types of species interactions with examples, and key adaptations (Allen's rule, Bergmann's rule, hibernation, aestivation).
How many questions from this chapter are on RankUp?
The RankUp app has 439 questions on Organisms and Populations, including 236 ELITE questions written for students aiming at AIR under 50. Every question has a detailed explanation.
