CDS 2017 Previous Year GK Questions with Answers

The correct answer is A, a nitrogenous base, deoxyribose sugar and phosphate group. Each nucleotide of DNA is made of these three parts, and many nucleotides joined together form the polynucleotide chain.

In a DNA strand, the sugar of one nucleotide is linked to the phosphate of the next by a phosphodiester bond, making a sugar-phosphate backbone. The nitrogenous bases stick out from this backbone: adenine, guanine, cytosine and thymine. Two such chains run in opposite directions and are held together by hydrogen bonds between the bases, A with T and G with C, giving the double helix described by Watson and Crick in 1953. The sugar is deoxyribose, which has one oxygen atom fewer than ribose.

B is wrong: ribose sugar is found in RNA, not DNA.

C is wrong: a DNA chain has only one kind of sugar, deoxyribose, and it must contain bases.

D is wrong: without a sugar the bases and phosphates cannot be linked into a chain.

Exam tip: DNA = deoxyribose + A, G, C, T; RNA = ribose + A, G, C, U.

The correct answer is C, New Guinea. With an area of about 7.86 lakh sq km, New Guinea is the world's second-largest island, after Greenland.

New Guinea lies just north of Australia and is shared by two countries: its western half belongs to Indonesia and its eastern half is the mainland of Papua New Guinea. It is mountainous and covered with dense rainforest. Australia is not counted here because it is treated as a continent. After Greenland and New Guinea, the next largest islands are Borneo, Madagascar, Baffin Island and Sumatra, in that order.

A is wrong: Borneo, shared by Indonesia, Malaysia and Brunei, is the third largest, at about 7.43 lakh sq km.

B is wrong: Madagascar, off the south-east coast of Africa, is fourth, at about 5.87 lakh sq km.

D is wrong: Sumatra, in Indonesia, is sixth, at about 4.73 lakh sq km.

Exam tip: largest islands in order: Greenland, New Guinea, Borneo, Madagascar, Baffin, Sumatra.

The correct answer is C, At the Second Continental Congress in 1775. The Congress met in Philadelphia in May 1775, soon after the fighting at Lexington and Concord, and in June it appointed George Washington commander-in-chief of the newly created Continental Army. He was chosen partly for his experience in the French and Indian War and partly because a Virginian at the head of a largely New England army would bind the colonies together. He held the command through the whole War of American Independence until the British surrender at Yorktown in 1781. Option A is wrong because the Boston Tea Party of December 1773 was a protest against the Tea Act and created no army. Option B is wrong because the First Continental Congress of 1774 only sent a petition to the king and agreed to boycott British goods. Option D is wrong because Washington had already led the army for a year when independence was declared. Exam tip: 1775 command, 1776 Declaration of Independence, 1781 Yorktown, 1783 Treaty of Paris.

The correct answer is A, 1 and 2 only, because the Pranami sect and the theosophists shaped Gandhi's thinking, while the Romantic poets did not. Gandhi's mother Putlibai belonged to the Pranami sect, a Vaishnava tradition that drew on both Hindu and Islamic teaching and held that faiths are one; the household he grew up in therefore treated religious tolerance as ordinary. As a law student in London he met theosophists who were reading the Bhagavad Gita in Edwin Arnold's translation, and it was through them that he first studied his own scripture seriously. Statement 3 is the odd one out, so options B and C are wrong: Gandhi's reading of English writers centred on Ruskin's Unto This Last, Tolstoy's The Kingdom of God is Within You and Thoreau's essay on civil disobedience, not on Wordsworth or the Romantics. Option D is wrong because it drops the theosophists. Exam tip: Gandhi's three book influences are Ruskin, Tolstoy and Thoreau.

The correct answer is D. The polar front jet is strongest in winter, not in summer, so this statement is the incorrect one. A jet stream is a fast, narrow ribbon of westerly wind in the upper troposphere, and its speed depends on the temperature contrast across the front below it. In winter the gap between polar and tropical air is at its widest, the pressure gradient steepens and the polar front jet can cross 300 km per hour; in summer the contrast weakens, the jet slows and shifts poleward. Option A is correct because a jet stream is indeed a narrow band of very high velocity wind, only a few hundred kilometres wide. Option B is correct because jet streams blow just below the tropopause, roughly 8 to 15 km above the surface. Option C is correct because they run as long meandering ribbons stretching thousands of kilometres around the globe. Exam tip: jet streams are strongest in winter, and India's weather turns on the easterly tropical jet in summer.