The enzymes that initiates digestion of starch in the mouth?

Correct Answer: A

Rationale: Salivary amylase (ptyalin) begins starch digestion in the mouth, making A correct.

Correct Answer: B

Rationale: Sodium is the predominant cation in extracellular fluid, critical for osmotic balance and nerve function.

Correct Answer: B

Rationale: Without aldosterone, sodium reabsorption decreases, as aldosterone promotes sodium retention in the kidneys.

Correct Answer: C

Rationale: ADH, from the posterior pituitary, increases water reabsorption, concentrating urine.

Correct Answer: D

Rationale: Excess ADH causes water retention, diluting plasma sodium and leading to hyponatremia.