UPSC Prelims 2022 · Question 48 of 98

UPSC Prelims 2022 question on Nitrogen Fixing Plants

Which of the following are nitrogen-fixing plants?

1. Alfalfa

2. Amarnath

3. Chickpea

4. Clover

5. Purslane (Kulfa)

6. Spinach

Select the correct answer using the code given below:

  1. 1, 3 and 4 only
  2. 1, 3, 5 and 6 only
  3. 2, 4, 5 and 6 only
  4. 1, 2, 4, 5 and 6
Show answer

Answer: A. 1, 3 and 4 only

Alfalfa (Option 1) – CORRECT: Alfalfa, also called lucerne, is a perennial flowering plant in the legume family Fabaceae. Symbiotic N2 fixation by alfalfa provides substantial amounts of nitrogen (N) to livestock operations, subsequent crops, and soil organic matter.

Amarnath (Option 2) – INCORRECT: Amaranthus is a cosmopolitan genus of annual or short-lived perennial plants. It is NOT a nitrogen-fixing plant.

Chickpea (Option 3) – CORRECT: The chickpea or chick pea is an annual legume of the family Fabaceae — a nitrogen-fixing plant.

Clover (Option 4) – CORRECT: Nitrogen is 'fixed' in clovers through a symbiotic relationship with Rhizobium bacteria that infects the plant's roots.

Purslane/Kulfa (Option 5) – INCORRECT: Purslane is a green, leafy vegetable (Portulaca oleracea). It is NOT a nitrogen-fixing plant.

Spinach (Option 6) – INCORRECT: Spinach is a leafy green flowering plant native to central and western Asia, of the order Caryophyllales — NOT a nitrogen-fixer.

Correct nitrogen-fixing plants: 1, 3 and 4 → Option (a).

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