Species: UPSC Previous Year Questions (Environment and Ecology)

Explanation

Azadirachta indica, commonly known as the Indian neem tree, is a tropical evergreen belonging to the Meliaceae family, native to the Indian subcontinent, renowned for its medicinal and ecological significance. Neem is typically grown in tropical and subtropical regions.

Statement 1 is correct: Neem oil and neem barks are used as an insect repellent and can be used for controlling the spread of some insects and mites.

Statement 2 is incorrect: While neem seeds contain oil, which has potential as biofuel, the manufacturing of hospital detergents is not a common or widespread use of neem seeds. The primary application of neem oil in hospital settings is in disin-fectants or antiseptic creams, not detergents specifically.

Statement 3 is correct: Neem oil has multiple applications in the pharmaceutical industry. Neem is considered a weed and based on its antimicrobial resistance and other antifungal properties, they are also used in pharmaceutical and cosmetic industries.

Explanation

Gangetic dolphins live in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Nepal, In-dia, and Bangladesh. The Ganges river dolphin can only live in freshwater. They are essentially blind. They are also called ‘susu’.

Statement 1 is correct: Dams and barrages disrupt the natural flow of rivers, reducing the availability of suitable habitats for the dolphins. They also fragment populations and prevent dolphins from migrating to areas with adequate food resources. These structures can obstruct the dolphins’ access to breeding and feeding grounds.

Statement 2 is incorrect: While crocodiles may compete with dolphins for food yet an increase in the population of crocodiles in rivers is not considered a threat to Gangetic dolphins.

Statement 3 is correct: Dolphins die as a result of accidentally being caught in fishing nets, also known as bycatch.

Statement 4 is correct: The use of pesticides and fertilizers in agricultural practices leads to water pollution, which can degrade the dolphins’ habitat by reducing water quality and food availability (as it affects the aquatic food chain).

Explanation

Option 2 is correct: Common mynas are native to South Asia, with their breeding range extending from Afghanistan through India and Sri Lanka to Bangladesh. They have been introduced to many tropical regions worldwide, except South America. While generally resident in India, occasional east-west movements occur. The Common Myna is an omnivorous, opportunistic feeder, often foraging on insects disturbed by grazing cattle. It thrives in urban environments and is known for its strong territorial instincts, often found in open woodlands.

Option 1 is incorrect: Painted storks forage in flocks in shallow waters along rivers or lakes. A wading bird that lives in the wet-lands of tropical Asia. They feed on fish, frogs, and insects in shallow water. It has distinctive pink tertial feathers Option 3 is incorrect: The habitat of Black-necked Crane is in the high altitude wetlands and grasslands of the Tibetan plateau, Sichuan (China), and eastern Ladakh (India). They are not opportunistic feeders.