The vitamin that is destroyed by excessive heat and light is: MCQ with Answer and Explanation

Explanation:
Dialysis artificially filters waste products (urea, creatinine) and excess fluid from the blood when kidneys fail, using a semipermeable membrane. Hemodialysis uses an external dialyzer, peritoneal dialysis uses the peritoneal membrane. Bypass is a surgical procedure, transfusion is blood transfer, endoscopy is visualization.

Explanation:
Spermiogenesis is the final stage of spermatogenesis, where the spherical, non-motile spermatids undergo a complex morphological transformation to become highly specialized, motile spermatozoa (sperm). This involves the formation of the acrosome, condensation of the nucleus, development of the flagellum (tail), and the shedding of excess cytoplasm. Spermiation is the subsequent release of these mature sperm into the tubule lumen.

Explanation:
The lac operon in E. coli is a classic example of an inducible operon. It is normally 'off' (repressed) because the lac repressor protein, produced by the 'i' gene, binds to the operator, preventing transcription of the structural genes (z, y, a) needed for lactose metabolism. However, when lactose is present in the environment, it is converted to allolactose, which acts as an inducer. Allolactose binds to the repressor, changing its shape and preventing it from binding to the operator, thus 'inducing' or allowing transcription to occur.