Question 59 from UPSC CSE 2014 - Science and Technology

Question

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

IASCODEX · Accepted Answer

Correct Option: B. algae and fungi

Strategy: Focus on the core relationship: lichens are a unique symbiotic association. Eliminate options involving mosses or bacteria since the classic biological pairing for lichens is algae with fungi. Recall from basic ecology that lichens represent the partnership of an algal and a fungal component, enabling colonization on bare rocks.

Key Info: ## About Lichens

Lichens are composite organisms from a symbiotic partnership between a fungus (mycobiont) and an alga or cyanobacterium (photobiont). The most common and classical association is between algae and fungi.

**Symbiotic Roles**
- The fungus provides structure and protection.
- The algal cells conduct photosynthesis to produce nutrients.

**Ecological Importance**
- They are pioneer species, initiating ecological succession by colonizing bare rocks and breaking them down into soil.
- They act as bioindicators of air quality.
- They contribute to soil formation.

**Distinctions**
Mosses are distinct non-vascular plants and do not form these symbiotic structures. While cyanobacteria can be a partner, the canonical association for most lichens is algae and fungi.

IASCODEX · Answer

Option A: algae and bacteria

IASCODEX · Answer

Option C: bacteria and fungi

IASCODEX · Answer

Option D: fungi and mosses