Biodiversity, plants & animals

Answer: (d) 3

River dolphins live only in fresh water and cannot pass from one river system to another through the sea. Finding the same kind of dolphin in both the Indus and the Ganga systems was therefore read as proof that the two systems were once joined, with a tributary such as the Yamuna or the Sutlej changing sides in the Pleistocene.

• ✗ 1. The Nadistuti (Nadi) Sukta is a hymn in praise of the rivers of north-west India. It names the rivers in order but says nothing about Pleistocene river courses.
• ✗ 2. Robert Bruce Foote is known for discovering Palaeolithic tools in South India (Pallavaram, 1863), not for exploring the Sutlej and the Yamuna.
• ✓ 3. A freshwater dolphin common to the Indus and the Ganga systems implies an old connection between them, which is exactly what the assertion claims. The Convention on Migratory Species document proposed by India treats the South Asian river dolphin, Platanista gangetica, as one species spread across rivers in India, Pakistan, Bangladesh and Nepal (the Indus form being a subspecies).
• • Since then The Indus and Ganges dolphins were long treated as one species; since 2021 scientists list them as two species, Platanista minor and Platanista gangetica (Britannica). The old argument used the single-species view.

Remember · The shared South Asian river dolphin of the Indus and Ganga systems is the classic clue that the two drainages were once linked through a shifting tributary.

📘 Read it in NCERT: Class 7 Exploring Society: India and Beyond (Part 1), Ch 8 (practise this chapter)

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Answer: (b) 1 and 2

The western hoolock gibbon, India's only ape, is assessed as Endangered by the IUCN, and Assam's Hollongapar Gibbon Wildlife Sanctuary in Jorhat is named after it. Gibbons are expert brachiators that swing arm over arm through the canopy, but they are small, light apes, not heavily built like gorillas.

• ✓ 1. Hollongapar Gibbon Wildlife Sanctuary (about 21 sq km, Jorhat district, Assam) is named after the hoolock gibbon; the western hoolock (Hoolock hoolock) is listed as Endangered on the IUCN Red List.
• ✓ 2. Gibbons have very long forearms and move mainly by brachiation, swinging from branch to branch and covering more than 3 m in a single swing.
• ✗ 3. Gibbons are the lightest apes, weighing roughly 4–13 kg; the agility comes from a slender, light build, not a heavy gorilla-like body.

Remember · Western hoolock gibbon: India's only ape, IUCN Endangered, Schedule I; Hollongapar Gibbon Sanctuary, Jorhat (Assam); moves by brachiation.

Question and answer: UPSC's provisional GS Paper I (2026, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (a) 1 only

Amur Falcons stop over in the Doyang area of Wokha district for about a month each October–November on their long migration to southern Africa. Mass hunting in 2012 gave way to protection by villagers, churches, youth groups and the forest department, which is why the roost now thrives. Satellite tags only record their routes; they do not guide the birds, and the falcons do not stay in India.

• ✓ 1. After the 2012 slaughter, local communities around Pangti and Doyang turned protectors, enforcing hunting bans; the safe roost is the product of that sustained community effort.
• ✗ 2. Satellite tagging (from 2013) was used to study the falcons' routes; migratory birds navigate on their own, and tags play no part in guiding them back.
• ✗ 3. The falcons are passage migrants: they spend about a month in Nagaland and then continue to southern Africa, so they have not become permanent residents.

Remember · Amur Falcon: breeds in Siberia–China–Mongolia, stops over in Nagaland (Pangti, Doyang, Wokha) in Oct–Nov, winters in southern Africa; a community-conservation success after 2012.

Question and answer: UPSC's provisional GS Paper I (2026, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) 1 and 3

The foxtail orchid grows perched on trees rather than in soil, and it is the State flower of Arunachal Pradesh and of Assam. It is not a North-east endemic, because the species ranges across South and South-east Asia.

• ✓ 1. The Botanical Survey of India describes Rhynchostylis retusa as an epiphytic herb: it lives on the branches of host trees. NCERT gives an orchid growing on a mango branch as its standard example of an epiphyte.
• ✗ 2. The Botanical Survey of India gives its range as India, Bhutan, Cambodia, Indonesia, Laos, Malaysia, Myanmar, Nepal, Philippines, Singapore, Sri Lanka, Thailand and Vietnam, so it is not restricted to North-east India.
• ✓ 3. Arunachal Pradesh's official state profile lists the Foxtail Orchid as its State Flower, and the Botanical Survey of India's State Flower sheet for Assam names the same orchid (kopou phul) as Assam's State Flower.

Remember · Foxtail orchid (Rhynchostylis retusa): an epiphyte; State flower of Arunachal Pradesh and Assam; widespread in Asia, not a North-east endemic.

📘 Read it in NCERT: Class 12 Biology, Ch 11 (practise this chapter)

Question and answer: UPSC's provisional GS Paper I (2026, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error