Ecosystems and Biodiversity Questions and Answers

Answer: C

The correct match is Nekton - active swimmers, Neuston - surface film, Benthos - bottom dwellers, Plankton - cannot move independently.

Nekton are strong swimmers such as fish that move against currents. Neuston live on or at the surface film of the water. Benthos live on the bottom, and plankton drift with the water and cannot swim against it.

This gives a-iii, b-i, c-ii and d-iv, which is code (C). The other codes put nekton or benthos with the wrong habit.

Answer: D

'Mountains and glaciers' is not counted as a major biome of India.

Biomes are large regions defined by vegetation type, such as tropical rain forest, tropical deciduous forest and temperate needle-leaf (coniferous) forest, all of which occur in India. Mountains and glaciers are landforms and ice features, not a vegetation-defined biome, and the key marks that option.

Options (A), (B) and (C) are real biomes of India, found in the Western Ghats and the north-east, the peninsular and central plateau, and the Himalayan slopes.

Answer: C

Occupying only part of the fundamental niche is the realized niche.

The fundamental niche is the full range of conditions and resources a species could use without competitors. When competitors are present, the species is confined to a part of it, which is the realized niche, as the question describes.

Geographic isolation is the separation of populations by physical barriers. Mutualism is a relationship between two species that benefit each other. 'Broad niche' describes a species with wide tolerances, not one that has been limited by competition.

Answer: C

Option (C) is not a characteristic of a community.

A community is the set of populations of different species living in one place and interacting. Options (A), (B) and (D) describe this, with the populations, the network of plants, animals and microbes, and the interacting individuals of different species.

Option (C) adds the interaction with the environment of matter and energy, which is the definition of an ecosystem: the community together with its non-living surroundings. So it is the statement that does not describe a community.

Answer: B

Krill, Crabeater Seal, Leopard Seal, Killer Whale is the correct food chain.

In the Antarctic food web krill feed on phytoplankton, crabeater seals eat mostly krill, leopard seals prey on crabeater seals and penguins, and killer whales prey on seals, so this chain climbs trophic levels in the right order.

Option (A) has Emperor penguins eating Adelie penguins, which they do not. Option (C) makes the leopard seal eat krill and then be eaten by an emperor penguin, and (D) has a killer whale eaten by a leopard seal, which is the wrong way round.

Answer: D

Uniform distribution suggests that members compete for access to a resource, according to the key.

Individuals spaced evenly apart are usually the result of antagonistic interactions such as territoriality, or of competition for a limited resource like water, light or nutrients, which keeps neighbours apart.

Low density does not by itself give even spacing. Resources distributed unevenly give a clumped pattern. Members that are neither attracted nor repelled give a random distribution, which is option (C).

Answer: A

Tropical forests have nearly constant day length and temperature.

Close to the equator the length of the day hardly varies through the year, and the temperature stays high and steady, which is the description in option (A).

Tundra has short, cool summers and long, cold winters, so (B) is wrong. Savanna has a marked wet and dry season and is warm throughout, so (C) is wrong. Temperate grasslands have cold winters and hot summers, not mild winters, so (D) is wrong.

Answer: C

Parasitic gall formation is related to parasite-specific enzymes, according to the key.

A gall is an abnormal growth of the host tissue produced when a parasite such as a gall insect or a nematode releases substances that alter the plant's growth. The key attributes this to enzymes of the parasite, which is the cause of the growth.

Antibodies are made by animals and do not apply to plant galls. Cysts are protective structures the parasite forms, not the stimulus for the gall. Host hormones are present but the trigger comes from the parasite.

Answer: D

Hot spots are rich in species, high in endemism and under constant threat.

Norman Myers defined a biodiversity hot spot as a region with a very large number of species, many of them endemic, which is also under serious threat from human activity. So (i), (ii) and (iv) are the features.

An area scarce in species (iii) cannot be a hot spot, which rules out the options containing it, and (A) leaves out the threat that is part of the definition.

Answer: D

A paddy field is an engineered ecosystem, according to the key.

A paddy field is made and managed by people, with ploughing, flooding, planting and harvest controlled, so it is an artificial or engineered ecosystem.

It is partly aquatic and partly terrestrial but is not simply a fresh water or a terrestrial ecosystem, since it is human-made. 'Auto ecosystem' is not a standard class of ecosystem.