Consider statements about cell biology: 1. The cell membrane is made of a phospholipid bilayer. 2. Ribosomes are the site of lipid synthesis. 3. The cytoskeleton provides structural support. Which are correct? MCQ with Answer and Explanation

Explanation:
Nitrogen fixation is the process by which atmospheric N₂ is reduced to ammonia, which is then converted into nitrates that plants can absorb. This can be biological (by bacteria like Rhizobium, Azotobacter), physical (lightning), or industrial (Haber-Bosch process). Nitrification is the oxidation of ammonia to nitrates. Ammonification releases ammonia from organic matter. Denitrification converts nitrates back to N₂.

Explanation:
Poultry farming involves rearing birds like chickens for the production of eggs (layers) and meat (broilers). Apiculture (beekeeping) not only produces honey but also significantly increases crop yields through enhanced pollination by bees. Dairy farming focuses on the breeding and rearing of cattle, buffaloes, etc., for milk production, not fish (which is pisciculture). Thus, statements 1 and 2 are correct.

Explanation:
Bacteria are unicellular prokaryotic organisms, characterized by the absence of a true nucleus and membrane-bound organelles. Fungi are eukaryotic organisms, possessing a true nucleus and membrane-bound organelles, and can be unicellular (yeasts) or multicellular (molds, mushrooms). Viruses are acellular, non-cellular entities; they consist of genetic material (DNA or RNA) enclosed in a protein coat (capsid) and lack any cellular structure or metabolic machinery. Thus, statements 1 and 2 are correct.