Ecosystems and Biodiversity Questions and Answers

Answer: D

The threats accepted are A and B, so the answer is Only A and B.

Rising sea surface temperature is the greatest threat to the Great Barrier Reef. Water that stays too warm makes corals expel the algae that feed them, causing the mass bleaching events of 2016, 2017 and 2020. Outbreaks of crown-of-thorns starfish, which eat coral polyps, are the other major direct cause of coral loss.

Shipping, including oil transport, and tourism are pressures that the Reef's managers regulate, but they are minor compared with warming and starfish outbreaks. The key therefore rejects the options built on C and D, and 'Only A' leaves out the starfish.

Answer: C

The adaptations are A and C, so the answer is A and C.

Lizards are cold-blooded: they cannot generate much body heat, so they regulate their temperature by behaviour. When it is hot, desert lizards burrow into the soil to escape the heat (A), and when it is cool they bask in the sun to warm up (C).

Losing heat rapidly through the body (B) and insulation by a thick fatty layer (D) are physiological methods used by warm-blooded animals such as mammals, not by desert lizards. Every option containing B or D is therefore wrong.

Answer: D

The correct matching is A-III, B-II, C-IV, D-I.

• A population is a group of similar individuals of the same species in an area (A-III).
• A community is the assemblage of individuals of different species living in an area (B-II).
• An ecosystem is the interaction between living organisms and their physical environment (C-IV).
• The ecosphere (biosphere) is the part of the Earth that contains all the world's ecosystems (D-I).

Item V, classifying organisms by their environment, matches none of the four terms and is a distractor. Options that use V, or give population the community's definition, are wrong.

Answer: B

The Red Data Book covers all four, so the answer is A, B, C and D.

The Red Data Book, maintained in its modern form as the IUCN Red List of Threatened Species, documents the conservation status of species across the living world: animals, plants and fungi. Arthropods, such as insects, spiders and crustaceans, are animals, so they are covered as well, and many butterflies, beetles and crabs are assessed in it.

The options limited to animals alone, or to two groups, leave out groups the book includes.

Answer: B

Karnataka had 524 tigers in the 2018 estimation.

The All India Tiger Estimation of 2018, released in July 2019, counted 2,967 tigers in India. Madhya Pradesh had the most, 526, and Karnataka came second with 524, followed by Uttarakhand with 442.

That is why 526 is the trap: it is Madhya Pradesh's figure, two more than Karnataka's. 442 is Uttarakhand's count, and 512 is not a state figure from that report.

Answer: C

An ecological niche is best defined as the role an organism plays in its community.

A niche is the functional position of a species in its ecosystem: what it eats, what eats it, when and where it is active, the resources it uses and how it affects other organisms. Ecologists often put it as 'the habitat is the address, the niche is the profession'.

The specific environment an organism inhabits is its habitat, the usual confusion. The range of habitats it may occupy describes its distribution, and the inorganic, non-living features of an area are its abiotic factors. None of these is the niche.

Answer: C

Evenness is measured when we use the Simpson index.

Species diversity has two parts: richness, the number of species, and evenness, how equally individuals are spread among those species. The Simpson index combines both: it gives the probability that two individuals picked at random belong to the same species, so a community dominated by one species scores very differently from one with the same species in equal numbers.

Species richness and the number of genera count kinds only and say nothing about how evenly individuals are distributed. Genetic diversity is variation within species, a different level of biodiversity.

Answer: C

The false statement is the efficiency of energy transfer depends on the total production at a particular trophic level.

Ecological (trophic transfer) efficiency is a ratio: production at one trophic level divided by production at the level below, typically around 10%. As a ratio it does not depend on how large the total production at a level is; a large and a small ecosystem can transfer energy with the same efficiency.

The other statements are true. Because energy is lost at each step, a trophic level can support more herbivores than carnivores. Birds and mammals spend most of their assimilated energy on keeping warm, so their production efficiency is low. Herbivores assimilate less of what they eat than carnivores do, because plant matter such as cellulose is harder to digest than meat.

Answer: C

The criteria are A, C and E, so the answer is A, C and E.

Biodiversity hotspots, a concept introduced by Norman Myers and applied by Conservation International, are regions that combine very high species diversity with a high level of endemism, at least 1,500 endemic vascular plant species, and serious threat, having lost at least 70% of their original habitat.

Vegetation density, ethno-botanical importance and species' adaptation to local climate are not hotspot criteria. India's hotspots are the Western Ghats and Sri Lanka, the Himalaya, Indo-Burma and Sundaland, which includes the Nicobar Islands.

Answer: C

Feeding on dead and decaying organic matter is saprophytic nutrition.

Saprophytes, such as many fungi and bacteria, secrete digestive enzymes onto dead matter and absorb the dissolved products. In doing so they decompose dead organisms and return nutrients to the soil.

Autotrophic organisms make their own food, holozoic organisms ingest solid food and digest it inside the body, and parasites draw food from a living host. None of these feeds on dead matter.