25 questions in 25 minutes on the NTA computer-based test interface, all from Organisms and Populations. +4 / -1 marking, instant score, full solutions. Free, no login.
A chapter test is the fastest honest check on whether a chapter has actually landed. This one draws 25 questions from Organisms and Populations, of which 22 are real NEET previous-year questions and 0 sit at the harder end of the bank. Sit it in one 25-minute block, the way you would in the hall.
Revising first? Read the Organisms and Populations chapter notes, then come back and take this test to check it stuck.
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Duration: 180 minutes · 180 questions · 720 marks maximum
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NEET CBT mock test: common questions
How many questions are in this Organisms and Populations mock test?
25 questions in 25 minutes, marked +4 for a correct answer and -1 for a wrong one, exactly like the real paper. 22 of them are NEET previous-year questions.
Is this the same interface as the real NEET CBT?
Yes. On-screen countdown, colour-coded question palette, Save & Next, Clear Response and Mark for Review, then an instant score with full solutions.
Should I take this before or after revising Organisms and Populations?
Both, and that is the point. Take it cold to find out what you actually do not know, revise from the chapter notes, then retake it to confirm the gap closed.
All 25 questions with answers and solutions
The complete paper in text form, with the correct option and a worked explanation for every question. Sit the timed test above first: the score is only worth having if you earn it. Then open this to revise, or to re-read a question you got wrong without replaying the whole paper.
Show all 25 questions with answers and solutions
Botany
- Q1Carnivorous animals like lions and leopards occupy the same niche, but lions predate mostly larger animals while leopards take smaller ones. This mechanism of avoiding competition is referred to as:
- Resource partitioning
- Altruism
- Character displacement
- Competitive exclusion
Answer: (A) Resource partitioning
By feeding on different prey sizes the two predators divide the shared resource, i.e. resource partitioning, which lets them coexist despite occupying the same niche and escapes competitive exclusion.
- Q2In a logistic growth curve, the asymptote is obtained when:
- K is greater than N
- K = N
- K is less than N
- The value of r approaches zero
Answer: (B) K = N
In logistic growth (dN)/(dt) = rN(K-N)/(K), when N equals the carrying capacity K the bracket (K-N)/K = 0, so dN/dt = 0 and the curve flattens into a horizontal asymptote at N = K.
- Q3CAM (Crassulacean Acid Metabolism) helps desert plants in:
- Conserving water
- Reproduction
- Disease resistance
- Secondary growth
Answer: (A) Conserving water
CAM plants keep their stomata closed during the hot day and open them at night to take in CO2, drastically reducing transpirational water loss. Thus CAM primarily helps conserve water in arid habitats.
- Q4The relation between algae and fungi in a lichen is:
- Protocooperation
- Parasitism
- Symbiosis
- Commensalism
Answer: (C) Symbiosis
In a lichen the alga photosynthesises food while the fungus provides water, minerals and shelter; both benefit in an obligate partnership, i.e. symbiosis (mutualism).
- Q5A sedentary sea anemone gets attached to the shell lining of a hermit crab. The association is best described as:
- Symbiosis (mutualism)
- Commensalism
- Amensalism
- Ectoparasitism
Answer: (A) Symbiosis (mutualism)
The sea anemone rides on the hermit crab’s shell, gaining mobility and food scraps, while protecting the crab with its stinging cells; both benefit, so it is a mutualistic symbiosis.
- Q6Which one of the following is one of the characteristics of a biological community?
- Natality
- Sex ratio
- Mortality
- Stratification
Answer: (D) Stratification
Stratification (the vertical layering of organisms into zones, e.g. canopy, understory, floor) is a community-level characteristic. Natality, mortality and sex ratio are attributes of a single population, not a community.
- Q7Special kinds of roots called pneumatophores are characteristic of plants growing in:
- Dryland regions
- Saline soils
- Marshy places and salt lakes
- Sandy soils
Answer: (C) Marshy places and salt lakes
Pneumatophores are negatively geotropic breathing roots that grow upward out of waterlogged, oxygen-poor mud (e.g. mangroves in marshes and salt lakes) to enable gas exchange for the submerged root system.
- Q8In which of the following plants are sunken stomata found?
- Hydrilla
- Nerium
- Guava
- Mango
Answer: (B) Nerium
Nerium (oleander) is a xerophyte and shows sunken stomata, partially covered by hairs and cuticle, to check transpiration. Hydrilla is a hydrophyte; mango and guava are mesophytes.
- Q9Geometric (J-shaped) representation of population growth is mathematically described by:
- A sigmoid plateau
- Zero population growth
- Logistic equation with carrying capacity
- dN/dt = rN (exponential/geometric increase)
Answer: (D) dN/dt = rN (exponential/geometric increase)
J-shaped (geometric) growth occurs under unlimited resources and is described by the exponential equation (dN)/(dt) = rN, integrating to Nₜ = N₀ eʳᵗ. The logistic equation (A) gives the S-shaped curve, not the J.
- Q10Cuscuta growing on a host shrub and deriving its nutrition from it represents which interaction?
- Commensalism (+ 0)
- Mutualism (+ +)
- Amensalism (− 0)
- Parasitism (+ −)
Answer: (D) Parasitism (+ −)
Cuscuta is a leafless stem parasite lacking chlorophyll that draws nutrition from its host, harming it. The parasite benefits while the host is harmed: parasitism (+ −).
- Q11Annual migration does not occur in the case of:
- Salmon
- Salamander
- Arctic tern
- Siberian crane
Answer: (B) Salamander
Salmon (anadromous), the Siberian crane and the Arctic tern are all famous annual migrants. The salamander shows hibernation, not annual migration, so it is the exception (C).
- Q12Keystone species in an ecosystem are those which:
- Are present in maximum number
- Attain a large biomass
- Are most frequent
- Contribute greatly to ecosystem properties (have a large regulatory effect)
Answer: (D) Contribute greatly to ecosystem properties (have a large regulatory effect)
A keystone species exerts a regulatory effect on community structure far out of proportion to its abundance, contributing strongly to ecosystem properties and maintaining diversity. It need not be the most numerous (A,B) or have the largest biomass (C).
- Q13Sunken stomata are the characteristic feature of a:
- Hydrophyte
- Mesophyte
- Xerophyte
- Halophyte
Answer: (C) Xerophyte
Sunken stomata sit in pits that trap humid air and reduce transpiration, an adaptation of xerophytes (dry-habitat plants) to conserve water. Hydrophytes and mesophytes have no such water-saving need.
- Q14Which of the following correctly pairs a plant with a semelparous (once-in-a-lifetime) flowering habit?
- Wheat (annual, harvested)
- Mango
- Bamboo species
- Rose
Answer: (C) Bamboo species
Certain bamboo species flower only once in their lifetime (often after many decades), produce a large number of seeds and then die, an example of big-bang/semelparous reproduction.
- Q15If the mean and the median for a certain character of a population are the same, the distribution is most likely:
- Bi-modal distribution
- T-shaped curve
- Normal distribution
- Skewed curve
Answer: (C) Normal distribution
In a normal (symmetric) distribution the mean, median and mode coincide. When the mean equals the median the data are symmetric, indicating a normal distribution; a skewed curve (D) would separate the mean and median.
- Q16Temperature changes in the environment affect most the body temperature of animals which are:
- Aquatic
- Homeothermic
- Desert living
- Poikilothermic
Answer: (D) Poikilothermic
Poikilotherms (cold-blooded conformers) cannot regulate their internal temperature, so their body temperature fluctuates with the environment. Homeotherms (A) maintain a constant body temperature regardless of ambient change.
- Q17An association of individuals of different species living in the same habitat and having functional interactions is called a:
- Ecosystem
- Ecological niche
- Population
- Biotic community
Answer: (D) Biotic community
A biotic community is an assemblage of populations of different species living together in a defined area with functional interactions. An ecosystem (C) additionally includes the abiotic environment; a population (D) is a single species.
- Q18In an ecosystem, the niche of a species refers to its:
- Competitive ability
- Place of occurrence only
- Centre of origin
- Functional role at its place of occurrence
Answer: (D) Functional role at its place of occurrence
Grinnell coined ‘niche’ for the functional role an organism plays in its ecosystem, not merely where it occurs (that is the habitat). Place of occurrence (B) is the habitat, not the niche.
- Q19Which of the following does NOT have stomata?
- Mesophytes
- Hydrophytes
- Submerged hydrophytes
- Xerophytes
Answer: (C) Submerged hydrophytes
Submerged hydrophytes (e.g. Hydrilla, Ceratophyllum) exchange gases directly through their thin epidermis under water and carry out no transpiration, so they lack functional stomata. Other groups retain stomata.
- Q20The formula for exponential population growth is:
- dt/dN = rN
- dN/dt = rN
- dN/rN = dt
- rN/dN = dt
Answer: (B) dN/dt = rN
Exponential growth is described by (dN)/(dt) = rN, where the rate of change of population is proportional to the current population N and the intrinsic rate r. This yields the J-shaped curve.
- Q21A mutually beneficial association necessary for the survival of both partners is:
- Both commensalism and amensalism
- Mutualism / symbiosis
- Commensalism
- Amensalism
Answer: (B) Mutualism / symbiosis
When both species benefit and cannot live separately (an obligatory, mutually essential association), it is mutualism/symbiosis, e.g. lichens or obligate pollination. Commensalism benefits only one partner.
- Q22An orchid growing as an epiphyte on the branch of a mango tree, without harming the tree, is an example of:
- Competition
- Commensalism
- Mutualism
- Predation
Answer: (B) Commensalism
The orchid (epiphyte) gains support/space while the mango tree is neither benefited nor harmed. One species benefits, the other is unaffected (+ 0): commensalism.
- Q23Which one of the following population interactions is widely used in medical science for the production of antibiotics?
- Commensalism
- Amensalism
- Mutualism
- Parasitism
Answer: (B) Amensalism
Antibiotic production exploits amensalism: a microbe such as Penicillium secretes chemicals (allelochemicals) that harm other microbes while itself remaining unaffected (- , 0). This inhibition is harnessed to make antibiotics.
- Q24Soil particles primarily determine its:
- Soil flora
- Water-holding capacity
- Field capacity
- Texture
Answer: (D) Texture
The size of the soil particles (gravel, sand, silt, clay) directly defines the soil texture. Texture in turn influences field capacity, water-holding capacity and flora, but those are consequences, not the property the particle size is.
- Q25A high density of an elephant population in an area can result in:
- Predation on one another
- Intraspecific competition
- Interspecific competition
- Mutualism
Answer: (B) Intraspecific competition
High density of a single species crowds members of the same species, intensifying competition among them for food, space and mates, i.e. intraspecific competition, a density-dependent regulating factor. Interspecific competition (C) is between different species.