Exams › NEET › Biology › Ecology
14 questions with worked solutions.
Q1. Succession on sand dune is
Answer: Psammosere
Succession on sand dunes is called psammosere because it begins on sandy substrates. The term 'psammo' refers to sand, making it the correct ecological succession type.
Q2. The possible beneficial affect of grazing animals is the
Answer: Addition of their excrete to the soil
Grazing animals can benefit ecosystems by depositing dung and urine, which add nutrients back into the soil. This helps improve soil fertility and supports plant growth.
Q3. Who proposed the term ecosystem?
Answer: Tansley
Arthur Tansley proposed the term "ecosystem" in 1935 to describe the whole complex of organisms and physical environment interacting together. The other names are associated with ecology, but not with coining this term.
Answer: Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Forests modify local airflow by increasing surface roughness and acting as barriers, which reduces wind velocity. That slower, altered circulation can trap suspended solids and gaseous substances, so the reason correctly explains the assertion.
Answer: particles of spray liquids and by condensation of vapours in air
Mists consist of very fine liquid droplets dispersed in air. They form either when liquids are sprayed into tiny particles or when vapours condense into droplets, which matches option B.
Answer: Four
Autotrophs include photosynthetic organisms and chemoautotrophs. In the list, Nostoc, Chara, Nitrosomonas, and Nitrobacter are autotrophs, while the others are heterotrophs or parasites.
Answer: Community itself modifies its own environment, thus causing its own replacement by new commuity
Autogenic succession is driven by the biotic community itself: organisms change soil, light, moisture, or nutrients, and those changes lead to replacement by another community. That matches the option describing self-modification causing self-replacement.
Answer: Assertion is correct but Reason is incorrect
Lichens and mosses are pioneer species because they are the first to establish on bare, dry habitats in xerarch succession. The reason is wrong because these species do not get established later; they appear early and help create conditions for subsequent communities.
Q9. Tree ecosystem is an example of :-
Answer: Detritus Food Chain
A tree ecosystem is mainly supported by dead organic matter such as fallen leaves, bark, and wood. Decomposers and detritivores process this material, so the food chain begins with detritus rather than living green plants being eaten directly.
Q10. Eutrophication is often seen in
Answer: Fresh water lakes
Fresh water lakes are especially prone to eutrophication because they can receive nutrient runoff from surrounding land and have limited water exchange. These nutrients trigger excessive algal growth, which depletes oxygen as the algae decompose.
Q11. Which one of the following cannot be considered as a decomposer?
Answer: Hyenas
Fungi and bacteria are true decomposers because they chemically break down dead organic matter. Hyenas are not decomposers; they are scavengers/carnivores that feed on animal flesh rather than decomposing it.
Q12. Term used to describe non-dominant species that dictates community structure is
Answer: Keystone species
A keystone species has a disproportionately large effect on community structure relative to its abundance. Even though it may not be dominant, it can control interactions and maintain the balance of the ecosystem.
Answer: oxygen
In eutrophication, excess nutrients trigger algal blooms. When the algae die and decompose, microbes use up dissolved oxygen, creating hypoxic conditions that can kill fish.
Q14. Heavy rainfall during summer produces
Answer: Forest
Heavy rainfall provides enough water for many trees to grow and compete successfully, which leads to dense, layered vegetation. That pattern is characteristic of forests rather than drier biomes like grasslands or deserts.