Oceans

Answer: (b) 2 and 3

Primary producers make their own food by photosynthesis. In the sea these are the phytoplankton, which include cyanobacteria and diatoms. Copepods are tiny crustaceans and foraminifera are shelled protists; both eat other organisms, so they are consumers.

• ✗ 1. Copepods are small crustaceans; they graze on phytoplankton or live as parasites on fish, so they are consumers, not producers.
• ✓ 2. Cyanobacteria (blue-green algae) are photosynthetic bacteria and form part of the ocean's phytoplankton.
• ✓ 3. Diatoms are single-celled, silica-walled algae that make their own food using sunlight; they are among the most important phytoplankton.
• ✗ 4. Foraminifera are single-celled protists with shells that capture food such as bacteria, diatoms and even copepods; they are consumers, even though some species harbour algae inside.

Remember · Ocean food chains start with phytoplankton (cyanobacteria, diatoms, dinoflagellates, coccolithophores). Zooplankton such as copepods and foraminifera are consumers.

📘 Read it in NCERT: Class 8 Curiosity, Ch 2 (practise this chapter) · Class 12 Biology, Ch 11 (practise this chapter)

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (b) 2 and 3 only

Statements 2 and 3 are correct. Seabed exploration rights in international waters come from the International Seabed Authority, not from the Global Ocean Commission, which was only an independent advisory body.

• ✗ 1. The Global Ocean Commission (launched 2013) was an independent international commission working on threats to the high seas; it issues no licences. Exploration areas are allocated by the International Seabed Authority (ISA), set up under UNCLOS.
• ✓ 2. India holds ISA exploration rights over 75,000 sq. km of the Central Indian Ocean Basin for polymetallic nodules, and a later ISA contract for polymetallic sulphides in the Indian Ocean.
• ✓ 3. Polymetallic nodules lying on the deep seafloor, including in the Central Indian Ocean Basin, carry rare earth elements alongside nickel, copper, cobalt and manganese.

Remember · The International Seabed Authority, not the Global Ocean Commission, licenses seabed exploration beyond national jurisdiction; India holds ISA contracts for nodules and sulphides.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error

Answer: (c) Both 1 and 2

Both statements are correct: winds push warm surface water to the western side of tropical oceans, while in the temperate zone the westerlies carry warm water to the eastern side, that is, to the west coasts of continents.

• ✓ 1. In the tropics the easterly trade winds push warm water west and hold it there, so the western side of an ocean is warmer than the east. This matches warm currents along the east coasts of continents in tropical latitudes and cool waters off their west coasts.
• ✓ 2. Ocean circulation follows the planet's wind pattern, and in the middle latitudes the surface winds are the westerlies, which carry warm water eastwards, so the eastern side of the ocean is the warm side. NCERT notes that west coasts of continents in middle and higher latitudes are bordered by warm waters, as in north-western Europe.

Remember · Tropics: trade winds pile warm water in the west of the ocean. Temperate zone: westerlies carry warm water to the east, so west coasts of continents there are mild.

📘 Read it in NCERT: Class 11 Fundamentals of Physical Geography, Ch 13 (practise this chapter) · Class 11 Fundamentals of Physical Geography, Ch 13 (practise this chapter) · Class 11 Fundamentals of Physical Geography, Ch 13 (practise this chapter) · Class 11 Fundamentals of Physical Geography, Ch 9 (practise this chapter)

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink · Report an error

Answer: (b) 2 only

Only statement 2 is correct: ice caps and glaciers hold about 2 per cent of Earth's water, well above the 0.68 per cent held as groundwater, while rivers and lakes together hold only about 0.009 per cent.

• ✗ 1. NCERT's table gives fresh water lakes 0.009 per cent and rivers 0.0001 per cent of all water, far less than groundwater at 0.68 per cent.
• ✓ 2. The same table gives ice caps 2.0 per cent (glaciers are counted with them), which is roughly three times the groundwater share of 0.68 per cent.

Remember · Earth's water: oceans 97.3%, ice caps and glaciers 2.0%, groundwater 0.68%, lakes 0.009%, atmosphere 0.0019%, rivers 0.0001%.

Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink · Report an error