UPSC CSE Prelims

Correct Option: C (2 and 3) Explanation: Lichens can attach directly to bare rock and mosses colonise rock or bark without soil; most ferns and mushrooms require substrate/nutrients not captured by that simple soil-free pioneer category. Statement / Pair / Item-wise Analysis: 1. Incorrect / does not qualify - Typical ferns need a moist substrate/organic medium; they are not the classic bare-rock pioneers intended. 2. Correct / qualifies - Lichens can colonise exposed rock without a soil layer. 3. Correct / qualifies - Mosses can grow on rock or bark and help form soil. 4. Incorrect / does not qualify - Mushrooms are fruiting bodies of fungi requiring decomposing organic matter or a host, not independent bare-surface colonisers. Option-wise Analysis: A. Incorrect-includes item 1, which is not valid (Typical ferns need a moist substrate/organic medium; they are not the classic bare-rock pioneers intended); includes item 4, which is not valid (Mushrooms are fruiting bodies of fungi requiring decomposing organic matter or a host, not independent bare-surface colonisers); omits valid item 2 (Lichens can colonise exposed rock without a soil layer); omits valid item 3 (Mosses can grow on rock or bark and help form soil). B. Incorrect-omits valid item 3 (Mosses can grow on rock or bark and help form soil). C. Correct-selects exactly the supported statements/items: 2, 3. D. Incorrect-includes item 1, which is not valid (Typical ferns need a moist substrate/organic medium; they are not the classic bare-rock pioneers intended); includes item 4, which is not valid (Mushrooms are fruiting bodies of fungi requiring decomposing organic matter or a host, not independent bare-surface colonisers); omits valid item 2 (Lichens can colonise exposed rock without a soil layer). Review note: Some epiphytic ferns and fungi can grow without mineral soil; question uses the textbook category of soil-free pioneers.