UPSC Static Quiz – Environment : 2 April 2026

Solution: D

• Phytoplankton (the “plants” of the sea) are primarily composed of Diatoms (with silica shells) and Dinoflagellates (some of which are bioluminescent or cause red tides).
• Zooplankton are the animal-like drifters, with Copepods being the most abundant and Krill being a vital food source for baleen whales.
• Meroplankton are “temporary” plankton—they include the larval stages of fish, crabs, and sea urchins that eventually grow into larger, non-planktonic forms.
• Holoplankton are organisms that spend their entire life cycle in a planktonic state (e.g., most copepods and jellyfish).

Solution: C

• Sea-grasses are unique because they are true vascular plants (angiosperms) that have adapted to a completely submerged life. They have roots, stems, and leaves, and most importantly, they produce flowers, pollen, and seeds.
• Seaweeds, however, are macroalgae. They are simpler organisms (protists) that lack a vascular system and do not produce flowers or seeds; they reproduce through spores, gametes, or fragmentation.
• Both are autotrophic (photosynthetic), and both are generally restricted to the photic zone because they need sunlight. Sea-grasses are crucial for stabilizing sediments with their roots, while seaweeds often attach to rocky substrates using holdfasts.

Solution: A

• Statement 1 is correct; environmental parameters like salinity and temperature are primary drivers of phytoplankton community structure.
• Statement 2 is incorrect; while some species are sensitive, phytoplankton as a group are remarkably diverse and adaptable, occupying waters from the Arctic to the Tropics (eurythermal/euryhaline ranges), though specific blooms may be triggered by narrow conditions.
• Statement 3 is correct; as the base of the food chain, any loss in their diversity affects higher trophic levels (zooplankton, fish, whales) and disrupts the biological carbon pump.

Solution: C

• The Man and the Biosphere (MAB) Programme is a long-standing intergovernmental scientific program launched in 1971 by the United Nations Educational, Scientific and Cultural Organization (UNESCO).
• The program’s primary aim is to establish a scientific basis for the improvement of relationships between people and their environments. It combines natural and social sciences with a view to improving human livelihoods and safeguarding natural and managed ecosystems, thus promoting innovative approaches to economic development that are socially and culturally appropriate, and environmentally sustainable.
• The most well-known outcome of the MAB Programme is the establishment of the World Network of Biosphere Reserves (WNBR). These reserves are designated as learning places for sustainable development, where interdisciplinary approaches are tested to understand and manage changes and interactions between social and ecological systems. India participates in this program, and several of its Biosphere Reserves are part of the WNBR.

Solution: B

• Statement 1 is incorrect. The Red Data Book, or the IUCN Red List of Threatened Species, is compiled and published by the International Union for Conservation of Nature (IUCN), not the UNEP. The IUCN is the global authority on the status of the natural world and the measures needed to safeguard it.
• Statement 2 is correct. The primary purpose of the IUCN Red List is to provide a comprehensive inventory of the global conservation status of biological species. It uses a set of objective criteria to evaluate the extinction risk of thousands of species and subspecies, categorizing them into different levels of threat, such as Critically Endangered, Endangered, and Vulnerable.
• Statement 3 is incorrect. The IUCN Red List is comprehensive and is not restricted to animals. It catalogues a wide range of organisms, including animals, plants, and fungi. While the assessment of some groups (like insects and fungi) is less complete than for vertebrates and plants, the scope of the Red List is intended to cover all forms of life.