NEET Biology Organisms and Populations MCQs Set 12

Answer: (d) Both Assertion and Reason are false.

Explanation:
1. Antarctic fishes show biochemical adaptations for survival in subzero temperatures.
2. Hence option (d) is correct: Both Assertion and Reason are false.

Teacher's Note:
1. Antarctic fishes survive through antifreeze proteins and not through blubber.
2. Blubber is fat, so both statements are wrong.

Answer: (b) Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Explanation:
1. Habitat is place of dewelling whereas niche represents ecological role of species.
2. Hence option (b) is correct: Both Assertion and Reason are true but the Reason is not a correct explanation of the Assertion.

Teacher's Note:
1. A niche is usually occupied by one species, and many species can share a habitat.
2. The Reason is true but does not explain the Assertion.

Answer: (a) Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Explanation:
1. Shivering is physiological adaptions.
2. Hence option (a) is correct: Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Teacher's Note:
1. Shivering produces heat in cold.
2. It is a physiological adaptation.

Answer: (a) Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Explanation:
1. Commensalism is +, 0 type of population interaction.   
2. Hence option (a) is correct: Both Assertion and Reason are true and the Reason is a correct explanation of the Assertion.

Teacher's Note:
1. The clown fish and anemone relation is described as commensalism in the NCERT text.
2. The fish is protected and the anemone is not obviously helped.

Answer: (c) a and c

Explanation:
1. Host-specific parasites and their hosts co-evolve (a), and parasites may reduce the population density of the host (c).
2. Parasites have poorly developed sense organs and often lack a digestive system, so (b) and (d) are wrong.
3. Hence option (c) is correct: a and c

Teacher's Note:
1. Parasites lose organs they do not need.
2. They show adaptations such as suckers, hooks and a high reproductive rate.

Answer: (a) Homoeostasis

Explanation:
1. An ecosystem tends to resist change because it is in a state of homeostasis (dynamic balance).
2. Feedback keeps its structure and function steady.
3. Hence option (a) is correct: Homoeostasis

Teacher's Note:
1. Homeostasis is a self-regulating balance.
2. Large disturbances can still break it.

Answer: (a) Loamy soil

Explanation:
1. Loamy soil has sand, silt and clay in good proportion, with good drainage and water holding.
2. So it is best for plant growth.
3. Hence option (a) is correct: Loamy soil

Teacher's Note:
1. Loam = balance of aeration and water retention.
2. Sand drains too fast and clay is too compact.

Answer: (a) Pedology

Explanation:
1. Pedology is the science of soil.
2. Acarology studies mites, and palaeontology studies fossils.
3. Hence option (a) is correct: Pedology

Teacher's Note:
1. Pedology = soil, pedon = soil unit.
2. Do not confuse it with petrology (rocks).

Answer: (c) Allows the water to percolate slowly into it

Explanation:
1. A good soil lets water percolate slowly.
2. It then holds enough water for roots and also stays aerated.
3. Hence option (c) is correct: Allows the water to percolate slowly into it

Teacher's Note:
1. Soil must neither hold all the water nor drain it quickly.
2. Moderate porosity is ideal.

Answer: (b) Richer in organic matter

Explanation:
1. Top soil is darker because it has more humus (organic matter).
2. Humus is formed by decomposition of litter.
3. Hence option (b) is correct: Richer in organic matter

Teacher's Note:
1. Dark colour = organic matter.
2. Deeper layers have less humus.

Answer: (d) It holds water & all essential nutrients in a definite proportion

Explanation:
1. A soil is fertile if it holds water and all the essential nutrients in the right proportion.
2. Only organic matter or only water holding is not enough.
3. Hence option (d) is correct: It holds water & all essential nutrients in a definite proportion

Teacher's Note:
1. Fertility depends on many factors together.
2. Good soil is also well aerated.

Answer: (b) Tropical rain forests

Explanation:
1. Forests near the equator receive heavy rain and warmth all year.
2. They are tropical rain forests.
3. Hence option (b) is correct: Tropical rain forests

Teacher's Note:
1. Tropical rain forests have the richest biodiversity.
2. They have several tree layers.

Answer: (a) Himalaya

Explanation:
1. Temperate evergreen forests of India occur in the Himalayan region.
2. West Bengal, Andaman and Rajasthan have other forest types.
3. Hence option (a) is correct: Himalaya

Teacher's Note:
1. Himalayan temperate forests contain oak, pine and rhododendron.

Answer: (a) Tundra

Explanation:
1. The tundra is a cold, treeless biome with permafrost, called the arctic desert.
2. Taiga is the coniferous forest south of it.
3. Hence option (a) is correct: Tundra

Teacher's Note:
1. Tundra has lichens, mosses and dwarf shrubs.
2. Rainfall is low.

Answer: (c) Tropical rain forests

Explanation:
1. Tropical rain forests have the greatest species richness of plants and animals.
2. Taiga and chaparral have much less.
3. Hence option (c) is correct: Tropical rain forests

Teacher's Note:
1. High rainfall plus high temperature gives high biodiversity.

Answer: (c) temperate deciduous plants

Explanation:
1. Temperate deciduous forests have a marked autumn when leaves turn red and yellow and fall.
2. Tropical and evergreen plants do not show this.
3. Hence option (c) is correct: temperate deciduous plants

Teacher's Note:
1. Seasonal change causes leaf fall.
2. Cold prompts chlorophyll breakdown.

Answer: (d) Grassland biomes

Explanation:
1. The veldts of Africa and the pampas of South America are temperate grasslands.
2. They are grassland biomes.
3. Hence option (d) is correct: Grassland biomes

Teacher's Note:
1. Match grasslands with regions: prairies (North America), steppes (Eurasia), pampas (South America), veldt (Africa).

Answer: (c) Grassland with scattered trees

Explanation:
1. Savannas are grasslands with scattered trees.
2. They are found in the tropics, for example in Africa.
3. Hence option (c) is correct: Grassland with scattered trees

Teacher's Note:
1. They have a long dry season.
2. Grasses are dominant.

Answer: (d) Living organisms + lithosphere + atmosphere + hydrosphere

Explanation:
1. The biosphere includes living organisms together with the lithosphere, atmosphere and hydrosphere.
2. It is the zone where life exists.
3. Hence option (d) is correct: Living organisms + lithosphere + atmosphere + hydrosphere

Teacher's Note:
1. Biosphere = all ecosystems of the earth.
2. It includes land, air and water.

Answer: (c) Alpine region

Explanation:
1. Rhododendron is characteristic of the alpine zone of the Himalayas.
2. It is a shrub of cold, high-altitude regions.
3. Hence option (c) is correct: Alpine region

Teacher's Note:
1. Alpine vegetation lies above the tree line.
2. Rhododendron, junipers and mosses occur there.