Free Mock Test 2026
Free NEET Ecology Important MCQs Practice Test — Practice Questions
1. The pioneer species in primary succession on a bare rock are generally:
- (A) Lichens
- (B) Mosses
- (C) Herbs
- (D) Trees
Answer: (A) Lichens
Lichens secrete acids that weather the rock and form soil, preparing the way for mosses.
2. In a mycorrhizal association, the fungus helps the plant mainly by:
- (A) Absorbing phosphorus from the soil
- (B) Fixing atmospheric nitrogen
- (C) Performing photosynthesis
- (D) Providing carbohydrates
Answer: (A) Absorbing phosphorus from the soil
The fungal hyphae absorb phosphorus from the soil, and the plant provides the fungus with carbohydrates.
3. Cuscuta growing on a hedge plant is an example of:
- (A) Mutualism
- (B) Commensalism
- (C) Amensalism
- (D) Parasitism
Answer: (D) Parasitism
Cuscuta is a stem parasite that takes nutrients from its host.
4. According to Allen's rule, mammals from colder climates generally have:
- (A) Longer ears and limbs
- (B) Thinner fur
- (C) Shorter ears and limbs
- (D) A larger surface area
Answer: (C) Shorter ears and limbs
Shorter ears and limbs reduce the surface area and so minimise heat loss in cold climates.
5. Which nutrient cycle has rocks as its main reservoir and no significant gaseous exchange with the atmosphere?
- (A) Carbon cycle
- (B) Nitrogen cycle
- (C) Phosphorus cycle
- (D) Oxygen cycle
Answer: (C) Phosphorus cycle
Phosphorus is released from rocks by weathering, and the gaseous input from the atmosphere is negligible.
6. A cuckoo laying its eggs in a crow's nest is an example of:
- (A) Mutualism
- (B) Brood parasitism
- (C) Predation
- (D) Commensalism
Answer: (B) Brood parasitism
The host bird incubates the parasite's eggs, which are often similar to its own.
7. Humification during decomposition leads to the formation of:
- (A) Inorganic salts
- (B) Humus
- (C) Detritus
- (D) Nitrates
Answer: (B) Humus
Humus is a dark, amorphous material that is resistant to microbial action and acts as a nutrient reservoir.
8. The mass of living organisms per unit area at a given time at a trophic level is called:
- (A) Gross primary productivity
- (B) Standing crop
- (C) Net productivity
- (D) Detritus
Answer: (B) Standing crop
Standing crop is measured as fresh or dry weight, or as the number of organisms, per unit area.
9. Diapause, seen in many zooplankton species, is:
- (A) A stage of suspended development during unfavourable conditions
- (B) Migration to a warmer region
- (C) A change in body colour
- (D) Active hunting at night
Answer: (A) A stage of suspended development during unfavourable conditions
Diapause is a stage of suspended development that helps organisms survive adverse conditions.
10. When resources are unlimited, a population grows exponentially, as described by:
- (A) dN/dt = rN
- (B) dN/dt = rN[(K − N)/K]
- (C) N = K
- (D) dN/dt = 0
Answer: (A) dN/dt = rN
Exponential growth gives a J-shaped curve described by dN/dt = rN.
11. The breakdown of detritus into smaller particles by organisms such as earthworms is called:
- (A) Leaching
- (B) Humification
- (C) Mineralisation
- (D) Fragmentation
Answer: (D) Fragmentation
Fragmentation increases the surface area available for microbial action.
12. Hydrarch succession, which begins in water, ultimately leads to:
- (A) Xeric conditions
- (B) A desert climax
- (C) Tundra
- (D) Mesic conditions
Answer: (D) Mesic conditions
Hydrarch succession proceeds from hydric to mesic conditions, ending in a mesic climax community.
13. Organisms that maintain a constant internal environment despite changes in the external environment are called:
- (A) Conformers
- (B) Migrants
- (C) Parasites
- (D) Regulators
Answer: (D) Regulators
Regulators use physiological or behavioural means to keep body temperature and osmotic concentration constant.
14. In Connell's experiment on barnacles, the smaller barnacle Chthamalus was excluded from the lower intertidal zone because of:
- (A) Predation
- (B) Lack of food
- (C) Wave action
- (D) Competition from Balanus
Answer: (D) Competition from Balanus
Balanus is a superior competitor and excludes Chthamalus from the lower zone.
15. Which of the following is NOT an attribute of a population?
- (A) Sex ratio
- (B) Species richness
- (C) Age distribution
- (D) Birth rate
Answer: (B) Species richness
Species richness describes a community, not a single-species population.
16. If N is the population density at time t, B the births, D the deaths, I the immigrants and E the emigrants, the density at time t+1 is:
- (A) N + [(B + D) − (I + E)]
- (B) N + [(B + E) − (D + I)]
- (C) N + [(B + I) − (D + E)]
- (D) N − [(B + I) − (D + E)]
Answer: (C) N + [(B + I) − (D + E)]
Natality and immigration increase density, while mortality and emigration decrease it.
17. The pyramid of biomass in a sea is generally:
- (A) Upright
- (B) Inverted
- (C) Spindle-shaped
- (D) Absent
Answer: (B) Inverted
Phytoplankton have small standing biomass but reproduce quickly, so the biomass of zooplankton and fish can exceed that of producers.
18. The rate of decomposition is slower when the detritus is rich in:
- (A) Nitrogen and water-soluble sugars
- (B) Simple sugars only
- (C) Lignin and chitin
- (D) Proteins only
Answer: (C) Lignin and chitin
Lignin and chitin are decomposed slowly. Detritus rich in nitrogen and water-soluble substances such as sugars decomposes faster.
19. A lichen is a close mutualistic association between:
- (A) Algae and bacteria
- (B) Fungi and bacteria
- (C) Fungi and algae (or cyanobacteria)
- (D) Mosses and fungi
Answer: (C) Fungi and algae (or cyanobacteria)
The fungus absorbs water and minerals, and the photosynthetic partner supplies food.
20. Producers in an ecosystem fix 10,000 J of energy. By the 10 per cent law, the energy available at the third trophic level is:
- (A) 100 J
- (B) 1,000 J
- (C) 10 J
- (D) 10,000 J
Answer: (A) 100 J
The second trophic level gets 1,000 J and the third gets 100 J.