UPSC Prelims 2014 GS Paper I · Q22 of 100 Environment & Ecology easy

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

  1. (a) algae and bacteria
  2. (b) algae and fungi ✓ UPSC's answer
  3. (c) bacteria and fungi
  4. (d) fungi and mosses

Why the answer is (b)

• A lichen is a mutualistic partnership between a fungus (which provides structure, water and minerals) and a photosynthetic partner — an alga or cyanobacterium — that supplies food — option (b).

• As pioneers of primary succession, lichens secrete acids that weather bare rock into soil.

• Bacteria with algae (a) or fungi (c), and fungi with mosses (d), do not form lichens.

• Hence option (b).

Why the other options are wrong

(a) algae and bacteria
Lichens involve fungi, not bacteria alone with algae.
(c) bacteria and fungi
Bacteria–fungi is not a lichen.
(d) fungi and mosses
Mosses are not lichen partners.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2014, held on 24 August 2014. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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