The disease caused by the bacterium Clostridium tetani is: MCQ with Answer and Explanation

Explanation:
During intense exercise, when oxygen supply is insufficient, muscle cells switch to anaerobic glycolysis, producing ATP and lactic acid from glucose. Lactic acid accumulation lowers pH, causing muscle fatigue, soreness, and cramps. It is later converted back to glucose in the liver (Cori cycle). Ethanol is produced by yeast fermentation.

Explanation:
The lac repressor protein (product of lacI gene) binds to the operator sequence, preventing RNA polymerase from transcribing the structural genes. When lactose is present, allolactose (inducer) binds the repressor, causing it to release the operator, allowing transcription. This is negative regulation.

Explanation:
Aldosterone, from the adrenal cortex, acts on the distal tubule and collecting duct to increase sodium reabsorption (and water follows) and potassium secretion, raising blood volume and pressure. ADH increases water reabsorption, ANP reduces sodium reabsorption, renin is an enzyme initiating the RAAS.