The enzyme pepsin is secreted by which cells of the gastric glands? MCQ with Answer and Explanation

Explanation:
The nephron is the structural and functional unit of the kidney, responsible for filtration, reabsorption, and secretion to form urine. Each kidney has about 1 million nephrons. A nephron consists of the Bowman's capsule, glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. Neurons are units of nervous system, alveoli of lungs, hepatocytes of liver.

Explanation:
The cell cycle consists of interphase (G1, S, G2) and M phase. DNA synthesis or replication occurs during the S (synthesis) phase, resulting in each chromosome having two sister chromatids. G1 is for cell growth and RNA/protein synthesis; G2 is for preparation for mitosis. M phase includes mitosis and cytokinesis. Accurate DNA replication in S phase is crucial for genetic continuity.

Explanation:
Pellagra, characterized by dermatitis, diarrhea, and dementia (3 Ds), is due to deficiency of niacin (vitamin B₃) or its precursor tryptophan. Niacin is part of NAD and NADP coenzymes.