Ecosystems and Biodiversity Questions and Answers

Answer: C

The role of the detritus food chain is recycling of resources.

The detritus food chain starts with dead organic matter rather than living plants. Detritivores such as earthworms and millipedes, and decomposers such as bacteria and fungi, break it down and release nitrogen, phosphorus and other nutrients back into the soil and water for producers to reuse.

Grazing describes the other chain, which starts with herbivores eating living plants. Transfer of food and assimilation happen in every food chain, so they do not describe the special role of the detritus chain.

Answer: C

The answer is Tall, hardwood evergreen trees.

Tropical evergreen rainforests grow where rainfall exceeds about 200 cm and there is no real dry season. Trees such as rosewood, mahogany and ebony rise to 45 m or more in a multi-layered canopy and keep their leaves all year. In India they are found in the Western Ghats, the north-east and the Andamans.

Grasses with few trees describes savanna. Short softwood trees fit coniferous or alpine forests, and short hardwood trees fit dry thorn or scrub forests.

Answer: D

The equilibrium model says an ecosystem always tends towards stability.

The classical equilibrium (balance of nature) view holds that ecosystems are self-regulating. After a disturbance, negative feedbacks and succession return the system to a stable climax state, as in Clements' climax concept.

The first three options describe the opposite, non-equilibrium view, in which disturbance and chance keep ecosystems from settling and they need not return to their original state. An ecosystem perishing under change is not what any equilibrium model predicts.

Answer: B

Such species are called allopatric.

Allopatric (Greek allos, other, and Latin patria, homeland) populations or species live in separate geographical areas, divided by a barrier such as a mountain range or sea. Allopatric speciation, through such isolation, is the commonest route to new species.

Sympatric species share the same area. Ecological equivalents are unrelated species filling the same niche in different regions, and ecotypes are genetically distinct local forms of a single species adapted to their habitat.

Answer: C

These organisms are called benthic.

The benthos are organisms living on, in or near the bottom sediment, such as insect larvae, worms, snails and mussels. Benthic macroinvertebrates are widely used as indicators of water quality.

Neuston live at the surface film, plankton drift in the water column, and nekton are strong swimmers such as fish that move against currents. None of these is tied to the bed.

Answer: A

Dengue is spread by Aedes mosquitoes.

Aedes aegypti, and to a lesser extent Aedes albopictus, carry the dengue virus. They bite by day and breed in small pools of clean water in containers, coolers and tyres, which is why dengue rises after the monsoon in towns. They also carry chikungunya and Zika.

Anopheles spreads malaria, and Culex spreads filariasis and Japanese encephalitis. Plasmodium is not a mosquito at all; it is the malaria parasite that Anopheles carries.

Answer: A

Such a wetland is an example of an ecotone.

An ecotone is a transition zone between two different ecosystems, here land and deep water. It holds species of both neighbouring communities and some of its own, so it is often richer in species than either, the 'edge effect'. Mangroves, estuaries and marshes are classic ecotones.

An ecological pyramid shows numbers, biomass or energy across trophic levels. An ecological race is a population of a species adapted to local conditions, and an ecological niche is the functional role and requirements of a species, not a zone between systems.

Answer: A

Kaziranga National Park is in Assam.

It lies on the south bank of the Brahmaputra in the Golaghat, Nagaon and Biswanath districts. It holds about two-thirds of the world's greater one-horned rhinoceroses, was declared a national park in 1974, became a UNESCO World Heritage Site in 1985 and a tiger reserve in 2006.

Meghalaya's best-known parks are Nokrek and Balphakram, Arunachal Pradesh has Namdapha, and Uttarakhand has Jim Corbett, so none of them is home to Kaziranga.

Answer: A

The keyed answer is the Primary producer.

All the energy that flows through an ecosystem enters at the producer level, where plants capture solar energy in photosynthesis. Producers have the largest energy budget of any trophic level: much of their gross production is spent on their own respiration, and only about 10 percent of the energy at one level passes to the next (Lindeman's ten percent rule).

Primary consumers receive only part of the producers' net production, secondary consumers about a tenth of that again, so each higher level handles less energy. Decomposers process dead matter from all levels, but the energy they use is itself only a fraction of what producers originally captured.

Answer: C

The zone is the Profundal zone.

In a lake or deep pond, the profundal zone is the deep water and bottom below the compensation depth, the depth at which light is just enough for photosynthesis to balance respiration. Below it, too little light penetrates, so respiration by decomposers and animals exceeds production and the zone depends on organic matter sinking from above.

The limnetic zone is the open, lit surface water above the compensation depth, where plankton production exceeds respiration. The benthic zone is a general term for the bottom at any depth, including the lit shallows. The intertidal zone belongs to sea coasts, not ponds.