Defence Previous Year GK Questions with Answers

The correct answer is D, Bowman's capsule. Each human kidney has about one million nephrons, and every nephron begins with a cup-shaped Bowman's capsule that encloses a knot of capillaries called the glomerulus. Blood enters the glomerulus under pressure, and water, salts, glucose, urea and other small molecules are pushed out through its walls into the capsule; this is ultrafiltration, the first step of urine formation. Proteins and blood cells are too large to pass and stay in the blood. The filtrate then flows through the tubule, where useful substances such as glucose and most of the water are reabsorbed. A, the Collecting duct, only gathers urine from many nephrons and carries it to the pelvis of the kidney. B, the Renal vein, carries filtered blood away from the kidney and is not part of a nephron. C, the Ureter, is the tube that takes urine from the kidney to the bladder. Exam tip: Bowman's capsule plus glomerulus is the Malpighian body, the filter of the nephron.

The correct answer is C, Rickets. Vitamin D helps the intestine absorb calcium and phosphorus, so without it the bones of a growing child stay soft and bend, giving bow legs, a pigeon chest and a large forehead; this disease is rickets. In adults the same deficiency causes osteomalacia, a softening of already formed bones. Vitamin D is called the sunshine vitamin because the skin makes it when sunlight falls on it; fish liver oil, egg yolk and milk are food sources. Its chemical name is calciferol. A, Beriberi, is caused by lack of vitamin B1 (thiamine) and affects the nerves and the heart. B, Scurvy, comes from lack of vitamin C (ascorbic acid) and causes bleeding gums. D, Pneumonia, is an infection of the lungs caused by bacteria or viruses, not a deficiency disease. Exam tip: remember the pairs, A night blindness, B1 beriberi, C scurvy, D rickets, K delayed clotting.

The correct answer is D, General theory of relativity. LIGO, the Laser Interferometer Gravitational-Wave Observatory in the USA, detected gravitational waves for the first time in September 2015 (announced in February 2016), and such waves were predicted by Einstein's general theory of relativity in 1916. General relativity treats gravity as the curving of space-time and says that huge accelerating masses, like two black holes spiralling into each other, send ripples through space-time at the speed of light. LIGO's two detectors at Hanford and Livingston measured a change in arm length smaller than the width of a proton. India is building a third detector, LIGO-India, at Hingoli in Maharashtra. A, String theory, has made no prediction that any experiment has yet confirmed. B, Special relativity, deals with motion at constant speed and does not include gravity. C, Quantum mechanics, describes atoms and particles, not gravitational waves. Exam tip: LIGO means gravitational waves, which means general relativity; the 2017 Physics Nobel went to Weiss, Barish and Thorne for it.

The correct answer is D, Magnesium hydroxide. Milk of magnesia is a white suspension of magnesium hydroxide, Mg(OH)2, in water, and its milky look gives it the name. It is a mild base, so it is taken as an antacid to neutralise excess hydrochloric acid in the stomach and relieve acidity; in larger doses it works as a laxative. Being only slightly soluble, it does not make the stomach strongly alkaline, which is why it is safe as a medicine. A, Magnesium bicarbonate, exists only in solution and is not used as a medicine. B, Magnesium carbonate, is used in chalk and as a drying powder for the hands in sports, and is not called milk of magnesia. C, Magnesium sulphate, is Epsom salt, used in bath salts and as a purgative. Exam tip: pair the common names: milk of magnesia is Mg(OH)2, Epsom salt is MgSO4.7H2O, milk of lime is a Ca(OH)2 suspension.

The correct answer is C, Zinc. Galvanisation is the coating of iron or steel with a thin layer of zinc so that the iron underneath does not rust. Zinc sits above iron in the reactivity series, so even when the coating is scratched, zinc corrodes first and keeps protecting the iron; this is called sacrificial protection. The zinc layer is usually put on by dipping the article in molten zinc (hot-dip galvanising) or by electroplating. Galvanised sheets are used for roofs, water pipes, buckets and electricity poles. A, Gallium, is a rare, low-melting metal and is never used for rust protection. B, Aluminum, forms its own protective oxide layer, but coating iron with aluminium is not called galvanisation. D, Silver, is too costly and is less reactive than iron, so it would not protect it sacrificially. Exam tip: galvanisation means a zinc coating on iron; a tin coating on iron is called tinning.

The correct answer is B. R. Ambedkar. Dr Ambedkar, chairman of the Drafting Committee, described the Directive Principles as a "novel feature" of the Constitution. He also compared them to the Instrument of Instructions that the Government of India Act, 1935 issued to the Governor-General and the Governors, with one difference: under the Constitution the instructions are addressed to the government by the people, not by a colonial power.

Jawaharlal Nehru moved the Objectives Resolution and shaped the Preamble, but this description is not his. Dr Rajendra Prasad was the President of the Constituent Assembly. S.N. Mukherjee was the Chief Draftsman of the Constitution in the Assembly, the official who put its provisions into legal language, which makes him a clever distractor. Other famous descriptions are worth pairing with their authors: K.T. Shah called the Directive Principles "a cheque on a bank, payable at the convenience of the bank", and T.T. Krishnamachari called them "a veritable dustbin of sentiments".