The technique of producing many identical copies of a plant from a single tissue is: MCQ with Answer and Explanation

Explanation:
Pellagra, characterized by dermatitis, diarrhea, and dementia (3 Ds), is caused by a deficiency of niacin (vitamin B₃) or its precursor tryptophan. It is common in populations with corn-based diets lacking tryptophan. Beriberi is due to B₁ deficiency, cheilosis to B₂, peripheral neuropathy to B₆. Niacin is a component of coenzymes NAD and NADP.

Explanation:
Cholera is a severe diarrheal disease caused by the bacterium Vibrio cholerae. AIDS is caused by the Human Immunodeficiency Virus (HIV), which is a retrovirus. Dengue fever is transmitted by the bite of an infected female Aedes aegypti mosquito, not Culex (which transmits filariasis and Japanese encephalitis). Thus, statements 1 and 2 are correct.

Explanation:
Emil Fischer proposed the lock-and-key model in 1894, suggesting that the enzyme's active site is exactly complementary to the substrate, like a key fits a lock. Koshland later proposed the induced fit model, which is more widely accepted. Michaelis and Menten developed enzyme kinetics equations.