Which of the following are nitrogen-fixing plants? 1. Alfalfa 2. Amaranth 3. Chickpea 4. Clover 5. Purslane (Kulfa) 6. Spinach Select the correct answer using the code given below:

Answer: A. Alfalfa, Chickpea, and Clover are nitrogen-fixing plants (only 1, 3, 4). Nitrogen fixation in plants is performed by SYMBIOTIC bacteria (Rhizobium spp.) living in root nodules of LEGUMES (family Fabaceae). They convert atmospheric N2 into ammonia usable by plants. (1) ALFALFA (Medicago sativa): LEGUME with nitrogen-fixing nodules. Widely grown as fodder. (2) AMARANTH (Amaranthus): NOT a legume — belongs to family Amaranthaceae. No nodulation; no nitrogen fixation. Grown as leafy vegetable and grain pseudo-cereal. (3) CHICKPEA (Cicer arietinum): LEGUME with nitrogen-fixing nodules. Major Indian pulse crop. (4) CLOVER (Trifolium): LEGUME with nitrogen-fixing nodules. Widely used as fodder and green manure. (5) PURSLANE/KULFA (Portulaca oleracea): NOT a legume — Portulacaceae family. No nitrogen fixation. Grown as a vegetable in India and globally. (6) SPINACH (Spinacia oleracea): NOT a legume — Amaranthaceae family. No nitrogen fixation. Leafy vegetable. So only 1, 3, 4 are legumes that fix nitrogen. Source: NCERT Class 12 Biology Ch 12 (Biotechnology and its Applications) / Ch 14 (Ecosystem) on biogeochemical cycles.