Rickets in children is caused by the deficiency of: MCQ with Answer and Explanation

Explanation:
The Krebs cycle (citric acid cycle) occurs in the mitochondrial matrix in eukaryotes. It oxidizes acetyl-CoA to CO₂, producing NADH, FADH₂, and GTP. The inner membrane houses the electron transport chain. Glycolysis occurs in cytoplasm, the Calvin cycle in chloroplast stroma. The matrix contains the necessary soluble enzymes.

Explanation:
Polygenic inheritance occurs when a single phenotypic trait is controlled by two or more different genes at different loci, each having an additive effect. Human skin color, height, and eye color are controlled by multiple genes (e.g., at least three genes for skin color). This results in a continuous range of phenotypes, forming a bell-shaped curve in a population.

Explanation:
Vitamin B₆ (pyridoxine, pyridoxal, pyridoxamine) is a coenzyme (pyridoxal phosphate, PLP) for many enzymes involved in amino acid metabolism, including transaminases and decarboxylases. B₁ acts in carbohydrate metabolism, B₂ in redox reactions, B₁₂ in methylation and DNA synthesis.