Ecosystem structure and functions — UPSC Prelims PYQs

With reference to the planet Earth, consider the following statements: I. Rain forests produce more oxygen than that produced by oceans. II. Marine phytoplankton and photosynthetic bacteria produce about 50% of world's oxygen. III. Well-oxygenated surface water contains several folds higher oxygen than that in atmospheric air. Which of the statements given above are correct?

With reference to perfluoroalkyl and polyfluoroalkyl substances (PFAS) that are used in making many consumer products, consider the following statements: 1. PFAS are found to be widespread in drinking water, food and food packaging materials. 2. PFAS are not easily degraded in the environment. 3. Persistent exposure to PFAS can lead to bioaccumulation in animal bodies. Which of the statements given above are correct?

Which one of the following shows a unique relationship with an insect that has coevolved with it and that is the only insect that can pollinate this tree?

Consider the following statements: Statement-I: The soil in tropical rain forests is rich in nutrients. Statement-II: The high temperature and moisture of tropical rain forests cause dead organic matter in the soil to decompose quickly. Which one of the following is correct in respect of the above statements?

In nature, which of the following is/are most likely to be found surviving on a surface without soil? 1. Fern 2. Lichen 3. Moss 4. Mushroom Select the correct answer using the code given below.

“Leaf litter decomposes faster than in any other biome and as a result the soil surface is often almost bare. Apart from trees, the vegetation is largely composed of plant forms that reach up into the canopy vicariously, by climbing the trees or growing as epiphytes, rooted on the upper branches of trees.” This is the most likely description of

Which of the following are detritivores? 1. Earthworms 2. Jellyfish 3. Millipedes 4. Seahorses 5. Woodlice Select the correct answer using the code given below

Which of the following have species that can establish a symbiotic relationship with other organisms? 1. Cnidarians 2. Fungi 3. Protozoa Select the correct answer using the code given below

Due to some reasons, if there is a huge fall in the population of species of butterflies, what could be its likely consequence/consequences? 1. Pollination of some plants could be adversely affected. 2. There could be a drastic increase in the fungal infections of some cultivated plants. 3. It could lead to a fall in the population of some species of wasps, spiders and birds. Select the correct using the code given below:

With reference to an initiative called ‘The Economics of Ecosystems and Biodiversity (TEEB)’, which of the following statements is/are correct? 1. It is an initiative hosted by UNEP, IMF and World Economic Forum. 2. It is a global initiative that focuses on drawing attention to the economic benefits of biodiversity. 3. It presents an approach that can help decision-makers recognize, demonstrate and capture the value of ecosystems and biodiversity. Select the correct answer using the code given below.

Which one of the following is the best description of the term ‘ecosystem’?

Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of

Which of the following adds/add carbon dioxide to the carbon cycle on the planet Earth? 1. Volcanic action 2. Respiration 3. Photosynthesis 4. Decay of organic matter Select the correct answer using the code given below:

Which one of the following is the process involved in photosynthesis?

If you walk through countryside, you are likely to see some birds stalking alongside the cattle to seize the insects disturbed by their movement through grasses. Which one of the following is/are such bird/birds? 1. Painted Stork 2. Common Myna 3. Black-necked Crane Select the correct answer using the code given below.

Which one of the following is the correct sequence of a food chain?

With reference to food chains in ecosystems, consider the following statements: 1. A food chain illustrates the order in which a chain of organisms feeds upon each other. 2. Food chains are found within the populations of a species. 3. A food chain illustrates the numbers of each organism which are eaten by others. Which of the statements given above is/are correct?

With reference to the food chains in ecosystems, which of the following kinds of organism is/are known as decomposer organism/organisms? 1. Virus 2. Fungi 3. Bacteria Select the correct answer using the codes given below:

Which one of the following terms describes not only the physical space occupied by an organism but also its functional role in the community of organisms?

In the grasslands, trees do not replace the grasses as a part of an ecological succession because of:

Which one of the following is the correct sequence of ecosystems in the order of decreasing productivity?

The Millennium Ecosystem Assessment describes the following major categories of ecosystem services— provisioning, supporting, regulating, preserving and cultural. Which one of the following is a supporting service?

Biodiversity forms the basis for human existence in the following ways: 1. Soil formation 2. Prevention of soil erosion 3. Recycling of waste 4. Pollination of crops Select the correct answer using the codes given below:

When the bark of a tree is removed in a circular fashion all around near its base, it gradually dries up and dies because