General Science Questions and Answers

Answer: C

The kangaroo rat of the North American deserts never drinks. It gets all the water it needs from the metabolic breakdown of the dry seeds it eats.

It survives by losing almost none: it has no sweat glands, produces extremely concentrated urine and nearly dry droppings, and recovers moisture from its own breath in its nasal passages.

Answer: A

The ostrich egg is the largest single cell - about 15 cm long and weighing up to 1.5 kg.

The yolk is the cell proper; the white and shell are added around it as the egg passes down the oviduct.

Answer: B

The normal fasting blood sugar level is about 80 to 120 mg per 100 ml of blood.

It is held in this range by insulin, which lowers it, and glucagon, which raises it. A persistently higher level indicates diabetes mellitus.

Answer: A

The nerve cell is the longest cell in the body. A single motor neuron can run from the base of the spine to the toe, over a metre in a person of average height.

Most of that length is the axon, a slender process along which the impulse travels.

Answer: A

Penicillin is isolated from a fungus, the mould Penicillium notatum.

Alexander Fleming noticed in 1928 that a stray colony of it had killed the bacteria around it on a culture plate. Florey and Chain later purified the drug, and the three shared the Nobel Prize in 1945.

Answer: B

Metal teapots have wooden handles because wood is a poor conductor of heat.

The metal body conducts heat readily from the tea, which would burn the hand; wood conducts it so slowly that the handle stays cool enough to hold. Plastic and bakelite are used for the same reason.

Answer: C

Oxygen is the most abundant element in the earth's crust, making up about 46 per cent by mass.

Silicon follows at about 28 per cent, aluminium at 8 per cent, iron at 5 per cent and calcium at 4 per cent. Most crustal rock is silicate, which is why the first two dominate.

Answer: A

A red blood cell lives about 120 days. Having no nucleus it cannot repair itself, and it is eventually broken down in the spleen and liver.

The bone marrow replaces about two million of them every second to keep the count steady.

Answer: C

The pituitary is called the master gland, because its hormones control the thyroid, the adrenal cortex, the gonads and growth throughout the body.

It is itself directed by the hypothalamus above it, which is why the hypothalamus is sometimes called the master of the master gland.

Answer: B

The adrenal glands control blood pressure. The cortex secretes aldosterone, which makes the kidney retain sodium and water and so raises blood volume, and the medulla secretes adrenaline, which constricts vessels and speeds the heart.

The thyroid and parathyroid regulate metabolism and calcium instead, and the thymus is part of the immune system.