Human Physiology Questions and Answers

Answer: A

Milk contains protein, calcium and vitamin D.

Milk is rich in protein (mainly casein) and calcium, and contains vitamin D (often added in fortified milk), together with fat, the sugar lactose and vitamin A. Calcium and vitamin D together are needed for strong bones and teeth.

Milk is a poor source of vitamin C and of iron, which is why the other options are wrong: each names vitamin C or iron as a nutrient of milk. Infants fed only milk for too long can develop iron deficiency for this reason.

Answer: B

The correct matching is a-iv, b-i, c-ii, d-iii.

• Liver: the largest gland in the body; it makes bile.
• Stomach: where protein digestion starts, by pepsin in the gastric juice.
• Gall bladder: where bile juice is stored.
• Pancreas: releases digestive juice into the small intestine (pancreatic juice).

Options A and C make the liver the place where protein digestion starts, which is the stomach's role. Option D makes the pancreas the largest gland and the liver the source of pancreatic juice, reversing them.

Answer: A

Nose bleeding happens because the pressure in blood vessels exceeds outside pressure.

Air pressure falls with altitude. At great heights the pressure of the blood inside the body becomes much greater than the air pressure outside, and the thin, delicate blood vessels in the nose can burst. The dry, cold air of high mountains adds to the effect.

The blood pressure does not fall below or equal the outside pressure, and blood thickening is not the reason given for nosebleeds.

Answer: D

Both the Assertion and the Reason are false.

Water holds far less dissolved oxygen than the same volume of air contains. Aquatic animals therefore generally breathe faster than land animals to obtain enough oxygen, so the Assertion that their breathing is slower is false.

The Reason is false for the same underlying fact: the amount of dissolved oxygen in water is small, not large. Since neither statement holds, all the options treating either as true are wrong.

Answer: D

The human circulatory system is closed, with double circulation.

It is closed because blood always flows within vessels: arteries, capillaries and veins. It is double because blood passes through the heart twice in each complete circuit: the pulmonary circulation (heart to lungs and back) and the systemic circulation (heart to body and back).

Open circulation, where blood bathes the tissues directly, is found in insects and most molluscs. Single circulation, with one pass through the heart, is found in fishes.

Answer: A

The correct combination is P - chief cells, Q - hydrochloric acid, R - oxyntic cells.

Pepsinogen is secreted by the chief (peptic) cells of the gastric glands. Hydrochloric acid, secreted by the oxyntic (parietal) cells, lowers the pH and converts pepsinogen into active pepsin, which then activates more pepsinogen itself.

Parietal and oxyntic cells are the same cells and secrete HCl, not pepsinogen, so the options naming them as P are wrong. Enterokinase acts in the small intestine, on trypsinogen. Gastrin is a hormone that stimulates acid secretion; it does not itself activate pepsinogen and is made by G cells, not oxyntic cells.

Answer: B

The correct match is P-2, Q-1, R-4, S-3.

• Aldosterone acts on the kidney tubules to increase reabsorption of Na⁺ and, with it, water.
• Luteinizing hormone stimulates the Leydig cells of the testis to make and secrete androgens.
• Atrial natriuretic factor, released by the heart's atria, dilates blood vessels and lowers blood pressure.
• Epinephrine increases the heart rate and the strength of contraction.

P-2, Q-3, R-4, S-1 swaps LH and epinephrine. The options starting P-1 or P-3 give aldosterone a function it does not have.