General Science GK Questions with Answers – Page 97

Balance is controlled by the inner ear, which holds the vestibular apparatus alongside the organ of hearing. It is made of three semicircular canals set at right angles to one another and two small sacs, the utricle and the saccule.

The speed of any wave is its frequency multiplied by its wavelength, so here 200 Hz times 2 m gives 400 metres per second.

A concave lens, also called a diverging lens, spreads out the rays that fall on it and so can never bring them to a real focus.

Wetting is decided by a contest between two forces: cohesion, the attraction among the molecules of the liquid itself, and adhesion, the attraction between the liquid and the solid surface.

The atomic number of an element is by definition the number of protons in its nucleus, so an atomic number of 11 means 11 protons.

A gram of fat yields about nine kilocalories, more than twice the yield of carbohydrate or protein, because its carbon chains are far less oxidised to begin with; this is also why fat is the body’s store of energy and why fatty food is called energy dense.

Iodine is needed to make thyroxine, the hormone of the thyroid gland; when the supply is short the gland works harder and enlarges into the swelling at the front of the neck called goitre, and in an infant the same shortage stunts growth and mental development as cretinism.

Kwashiorkor appears when a child gets enough calories but far too little protein, typically after being weaned onto a starchy gruel; the signs are swelling of the feet and face, a distended belly, thin and discoloured hair and an apathetic look, while the muscles are not severely wasted.

These four dissolve in fat and not in water, so they travel with dietary fat, are stored in the liver and in body fat, show their deficiency only after a long shortage, and can be toxic in excess.

Retinol is vitamin A, and it is the raw material of rhodopsin, the pigment in the rod cells of the retina that lets us see in dim light; when it is short the eye cannot adjust to darkness, which is night blindness, and a longer shortage dries the conjunctiva as…

Vitamin D, chemically calciferol, is needed for the absorption of calcium and phosphorus from the intestine, so a child short of it cannot mineralise growing bone; the legs bow, the wrists thicken and the chest deforms, and the disease is rickets, while the same shortage in an adult softens formed…

Vitamin B12 is chemically cyanocobalamin, and the cobalt atom at the centre of its ring is what the name points to; it is the only vitamin that contains a metal, it is absorbed only with the help of intrinsic factor secreted by the stomach, and its shortage gives pernicious anaemia.

Vitamin B3 is niacin, also called nicotinic acid, and its shortage gives pellagra, remembered by the three Ds of dermatitis, diarrhoea and dementia, with death as a fourth if it is untreated; the disease appeared where maize was the staple, because the niacin in maize is bound and poorly absorbed.

Vitamin K, chemically phylloquinone, is needed by the liver to make prothrombin and other clotting factors, so a shortage of it makes bleeding last longer and can cause haemorrhage in a newborn; green leafy vegetables supply it and the bacteria of the large intestine make part of our requirement.

Thiamine is vitamin B1, and its shortage causes beriberi, in which the nerves and the heart are affected, giving weakness, loss of sensation in the legs and in the wet form swelling and heart failure; the disease was common where polished rice was the staple, since polishing removes the thiamine-rich…

Vitamin C, chemically ascorbic acid, is needed to make collagen, the protein that holds tissues together; without it the gums swell and bleed, wounds refuse to heal and the joints ache, and the disease is called scurvy.

Amylase breaks starch into the sugar maltose; a lipase works on fat, and saliva carries no significant lipase, so the statement pairs the right action with the wrong enzyme.

It is formed from the roots of the lower spine, passes through the buttock and runs down the back of the thigh to the leg and foot, and its compression by a slipped disc causes the pain called sciatica.

An injury here is fatal because these actions cannot be done at will.

It quickens the heartbeat, raises the blood pressure, widens the air passages, sends more blood to the muscles and releases glucose from the liver, so that the body is ready to fight or to run.