Human Physiology Questions and Answers

Answer: B

The correct sequence is (iv), (iii), (ii), (i).

1. The cow swallows grass quickly, with little chewing (iv).
2. The food is stored in the first part of the stomach, the rumen (iii).
3. There it is partially digested by microbes, forming cud (ii).
4. Later the cud returns to the mouth and the cow chews it at leisure (i), before it passes on for full digestion.

Cows are ruminants, and this is rumination. Any order that puts chewing the cud before storage and partial digestion is wrong, because the cud is made in the rumen.

Answer: B

Lactic acid is produced by anaerobic respiration in humans.

During heavy exercise the muscles run short of oxygen and break glucose down without it. In human muscle cells this gives lactic acid and a little energy; the build-up of lactic acid is linked with muscle cramps.

Aerobic respiration breaks glucose down completely to carbon dioxide and water. Anaerobic respiration in yeast is alcoholic fermentation, producing ethanol and carbon dioxide. The rise of dough with yeast and sugar is caused by that carbon dioxide, not by lactic acid.

Answer: C

The mismatched pair is Adrenaline - Pituitary Gland.

Adrenaline is secreted by the adrenal glands, which sit on top of the kidneys. It prepares the body for emergencies by raising heart rate, blood pressure and blood sugar.

The other pairs are correct: estrogen is made by the ovaries, thyroxine by the thyroid gland, and testosterone by the testes. The pituitary gland makes hormones such as growth hormone and the hormones that control other glands, but not adrenaline.

Answer: B

The set is oesophagus, large intestine, rectum.

None of these three organs secretes digestive enzymes or carries out the breakdown of food. The oesophagus only carries food to the stomach by peristalsis; the large intestine absorbs water and some salts from undigested food; the rectum stores the waste before it is passed out.

Each of the other sets includes an organ where digestion happens. Digestion of starch begins in the buccal cavity, through salivary amylase, and the small intestine is where digestion is completed.

Answer: C

The blanks are: right ventricle, pulmonary arteries, pulmonary veins, left ventricle and right auricle.

The right ventricle pumps blood into the pulmonary artery (A). The pulmonary arteries carry deoxygenated blood to the lungs (B), and the pulmonary veins bring oxygenated blood back to the heart (C). Blood passes from the left atrium into the left ventricle (D), which pumps it to the body. The right auricle (atrium) receives deoxygenated blood from all parts of the body (E).

The left ventricle pumps into the aorta, not the pulmonary artery, and the pulmonary veins and arteries are the other way round in the remaining option, so only the order right ventricle, pulmonary arteries, pulmonary veins, left ventricle, right auricle fits.

Answer: A

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

Adrenal hormones regulate the body's salt and water balance, so their deficiency causes salt imbalance (a-iv). Too little growth hormone in childhood causes dwarfism (b-i). Thyroxine needs iodine, and its deficiency causes goitre, a swollen thyroid (c-ii). Too little insulin causes diabetes, because blood sugar is not controlled (d-iii).

The other options swap these, for example linking thyroxine with diabetes or insulin with goitre.

Answer: B

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

• (a) Muscles move the body by contracting and relaxing.
• (b) Bones are the hard structures that form the skeleton.
• (c) Cartilage is the part of the skeleton that can be bent; it is softer and more flexible than bone, as in the ear and the nose.
• (d) The rib-cage joins the chest bone (sternum) and the backbone to enclose the heart and lungs.

Every other option pairs at least one description with the wrong structure: the first, for instance, calls cartilage the part that moves the body and gives the rib-cage the job of forming the whole skeleton.

Answer: B

The gland that secretes more than two hormones is the pituitary.

The pituitary gland at the base of the brain produces many hormones, including growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, prolactin, follicle-stimulating and luteinising hormones, and (from its posterior lobe) oxytocin and antidiuretic hormone. Because it controls several other glands it is often called the master gland.

In the school-level account the other glands each make fewer: the pancreas is known for insulin and glucagon, the thyroid for thyroxine, and the adrenal gland is taught mainly as the source of adrenaline. None matches the long list of the pituitary.

Answer: B

X, Y and Z are vitamin C, iron and citrus fruits.

Bleeding gums are a sign of scurvy, the deficiency disease of vitamin C. Vitamin C helps the body absorb iron from plant foods, and it is plentiful in citrus fruits such as oranges, lemons and amla.

The other combinations do not fit the symptom. Vitamin D deficiency causes rickets (it aids calcium absorption). Vitamin A deficiency causes night blindness. The B vitamins cause conditions such as beriberi, not bleeding gums.

Answer: D

The blood test is done to check for microbes in blood.

Malaria is caused by Plasmodium, a single-celled parasite (a microbe) passed on by the bite of an infected female Anopheles mosquito. The parasites multiply inside red blood cells, so a blood smear or rapid test detects them and confirms the disease.

Haemoglobin and iron tests check for anaemia, which malaria can cause but cannot confirm. Mosquito eggs are never found in blood; mosquitoes lay their eggs in water.