UPSC CAPF 2021 Previous Year GK Questions with Answers

The correct answer is C, Cell wall. Animal cells are bounded only by a flexible cell membrane; a rigid cell wall is found in plants, fungi and bacteria.

In plant cells the cell wall lies outside the cell membrane and is made mainly of cellulose; it gives shape, strength and protection against bursting when the cell takes in water. Fungi have walls of chitin and bacteria of peptidoglycan. Animal cells lack it, which lets them change shape, move and form tissues such as muscle. Other structures usually absent from animal cells are chloroplasts and a large central vacuole, while centrioles are typical of animal cells.

A is wrong: the cell membrane (plasma membrane) surrounds every living cell, animal or plant.

B is wrong: the endoplasmic reticulum, which makes proteins and lipids, is present in animal cells.

D is wrong: lysosomes, the digestive bags called suicide bags of the cell, are characteristic of animal cells.

Exam tip: plant cell = cell wall, chloroplast, large vacuole; animal cell = centrioles and lysosomes, no cell wall.

The correct answer is B. A short-sighted (myopic) person sees near things clearly but distant things blurred, and a concave lens corrects it.

In myopia the eyeball is too long or the eye lens too strongly curved, so light from a distant object comes to a focus in front of the retina instead of on it. The far point of the eye moves closer than infinity. A concave (diverging) lens of suitable power spreads the incoming rays slightly, so they focus exactly on the retina. Its power is negative, measured in dioptres.

A is wrong: blurred near vision with clear distant vision is long-sightedness (hypermetropia), and both the defect and the lens are mismatched here.

C is wrong: it describes hypermetropia but pairs it with a concave lens.

D is wrong: the symptoms are right for myopia, but a convex lens would make it worse.

Exam tip: myopia = near clear, far blurred, concave lens; hypermetropia = far clear, near blurred, convex lens; presbyopia = age, often bifocals.

The correct answer is A, 5 cm, converging. A real, inverted image of the same size forms only when the object sits at twice the focal length of a convex lens, so 2f = 10 cm and f = 5 cm.

For a convex (converging) lens, an object placed at 2F gives a real, inverted image of equal size at 2F on the other side. Check with the lens formula 1/v − 1/u = 1/f: with u = −10 cm and v = +10 cm, 1/f = 1/10 + 1/10 = 1/5, so f = +5 cm. A positive focal length confirms a converging lens. Magnification m = v/u = −1, which means same size and inverted.

B is wrong: a diverging (concave) lens always forms a virtual, erect and diminished image, never a real one.

C is wrong: with f = 20 cm the object at 10 cm would be inside the focus and the image would be virtual and enlarged.

D is wrong: a concave lens cannot form a real image, whatever its focal length.

Exam tip: convex lens, object at 2F gives image at 2F, real, inverted and the same size; u = v = 2f.

The correct answer is C, Infrared and microwave radiations. Both kinds of radiation carry energy that food absorbs as heat, and both are used in everyday kitchens.

Infrared radiation is the heat radiation given out by hot bodies: a grill, a toaster, an oven element or glowing coals cook the surface of food mainly by infrared rays. A microwave oven uses microwaves of about 2.45 GHz; water molecules in the food are polar, so they keep turning with the oscillating field and the friction heats the food from within. So two different bands of the spectrum are put to use in cooking.

A is wrong: infrared is used, but it leaves out the microwave oven.

B is wrong: microwaves are used, but grills and toasters cook with infrared.

D is wrong: X-rays, gamma rays and ultraviolet are harmful ionising or high-energy radiations and radio waves carry too little energy; none of them is used to cook.

Exam tip: microwave oven = about 2.45 GHz, heats water molecules; grill and toaster = infrared.

The correct answer is A, Nizam Shahis : Bijapur, which is the mismatched pair. The Nizam Shahis ruled from Ahmadnagar, founded by Malik Ahmad in 1490, while Bijapur belonged to the Adil Shahis of Yusuf Adil Shah. All five Deccan Sultanates grew out of the break-up of the Bahmani kingdom between about 1490 and 1518, and four of them joined hands to crush Vijayanagara at the battle of Talikota in 1565. Bijapur is remembered for the Gol Gumbaz, Golconda for its fort and diamonds, and Ahmadnagar for Chand Bibi’s defence against the Mughals. Option B is a correct pair, because the Barid Shahis held Bidar, the last Bahmani capital. Option C is a correct pair, because the Qutb Shahis of Quli Qutb Shah ruled Golconda and later founded Hyderabad. Option D is a correct pair, because the Imad Shahis held Berar, the first province to break away and the first to be annexed by Ahmadnagar. Exam tip: Ahmadnagar Nizam Shahi, Bijapur Adil Shahi, Golconda Qutb Shahi, Bidar Barid Shahi, Berar Imad Shahi.

The correct answer is C, Kolkata. The Kolkata port, now named Syama Prasad Mookerjee Port, stands on the Hooghly river about 200 kilometres inland from the Bay of Bengal, which makes it the only riverine major port in the country. Opened in 1870, it is also the oldest operating major port in India and serves a vast hinterland covering eastern India, Nepal and Bhutan. Its handicap is the silt the Hooghly carries: the channel must be dredged all the time, and because large modern ships still cannot reach the city, the Haldia Dock Complex was built downstream to take them. Option A is wrong because Mormugao in Goa is a coastal natural harbour at the mouth of the Zuari, famous for iron ore exports. Option B is wrong because Deendayal port, formerly Kandla, is a tidal sea port in the Gulf of Kachchh in Gujarat. Option D is wrong because Paradip in Odisha is an artificial deep water sea port on the coast. Exam tip: Kolkata is the only riverine major port, on the Hooghly, with Haldia as its deep water partner.

The correct answer is D, Chin Khilich Khan. Chin Qilich Khan, better remembered by his title Nizam-ul-Mulk Asaf Jah, was a Mughal noble appointed governor of the Deccan by Muhammad Shah. Tired of court intrigue at Delhi, he returned to the south, defeated his rival Mubariz Khan at Shakar Kheda in 1724 and from then on ruled the Deccan as an independent prince in all but name, founding the Asaf Jahi or Nizam dynasty of Hyderabad that lasted until 1948. He kept the forms of Mughal loyalty, struck coins in the emperor’s name, yet appointed his own officers and made war and peace on his own. Option A is wrong because Asaf Jah II, that is Nizam Ali Khan, was a later ruler of the same line, not its founder. Option B is wrong because Bahadur Shah was the Mughal emperor who ruled from 1707 to 1712. Option C is wrong because Alivardi Khan made himself independent in Bengal, not Hyderabad. Exam tip: Hyderabad 1724 Chin Qilich Khan, Awadh 1722 Saadat Khan, Bengal Murshid Quli Khan.

The correct answer is B, Abhaya Mudra. Early Mathura Buddhas show the right hand raised with the palm facing out, the gesture that says "fear not". The Mathura School flourished under the Kushanas in the first centuries CE, at the same time as the Gandhara school of the north-west. Mathura sculptors worked in the local spotted red sandstone and gave the Buddha a round smiling face, a shaven head with a spiral top-knot and a strong, fleshy body, a style that was wholly Indian. The seated Buddha from the Katra mound, now in the Mathura Museum, is a well-known example with the right hand in abhaya. Option A is wrong because the dhyana mudra of meditation, with hands resting in the lap, is typical of Gandhara images. Option C is wrong because the dharmachakra mudra of teaching became famous later, as in the Gupta-period Buddha of Sarnath. Option D is wrong because the varada mudra of giving, with the palm lowered, is seen more often in later images. Exam tip: Mathura means red sandstone and abhaya; Gandhara means grey schist and dhyana.

The correct answer is C, Anabaena. Anabaena is a cyanobacterium, a prokaryote with no true nucleus, and all prokaryotes are placed in Monera. In R.H. Whittaker's five-kingdom classification (1969), Monera holds the bacteria and the cyanobacteria, or blue-green algae, whose cells have no nuclear membrane and no membrane-bound organelles. Anabaena grows as chains of cells and has special thick-walled cells called heterocysts that fix nitrogen from the air. It lives inside the small water fern Azolla, which is why Azolla is used as a biofertiliser in paddy fields. Option A is wrong because diatoms are single-celled eukaryotes with glass-like silica walls, placed in Protista; their deposits form diatomaceous earth. Option B is wrong because Euglena is a protist that makes its own food in light but feeds like an animal in the dark. Option D is wrong because Ulothrix is a filamentous green alga with a true nucleus, grouped with plants. Exam tip: no true nucleus means Monera; Anabaena and Nostoc are the nitrogen-fixing cyanobacteria to remember.

The correct answer is C, Nitrogen. Nitrogen is an unreactive gas, so it drives the oxygen out of the packet and stops the oil in the chips from getting oxidised. Rancidity is the oxidation of fats and oils in food, which spoils their smell and taste. Chips are fried in oil, so they turn rancid quickly once they meet air. Filling the pack with nitrogen keeps oxygen out and also acts as a cushion that stops the chips from breaking in transport. Other ways to slow rancidity are adding antioxidants, storing food in airtight containers and keeping it in a refrigerator. Option A is wrong because carbon dioxide is used for fizzy drinks and some other foods, but the standard gas for chips is nitrogen, which is cheap and very unreactive. Option B is wrong because hydrogen is highly inflammable and unsafe inside food packs. Option D is wrong because oxygen is the very gas that causes rancidity in the first place. Exam tip: rancidity is oxidation of fats; nitrogen flushing and antioxidants prevent it.

The correct answer is C, minimum support price. The MSP is announced before sowing so that farmers know the lowest price at which the government will buy their crop. The Union Government fixes it on the recommendation of the Commission for Agricultural Costs and Prices (CACP), set up in 1965, and the final approval comes from the Cabinet Committee on Economic Affairs. It is announced separately for kharif and rabi crops, while sugarcane gets a fair and remunerative price instead. Wheat was the first crop brought under MSP, in 1966-67, at the start of the Green Revolution. Option A is wrong because a buffer stock is grain the government holds for food security, and no "buffer price" is announced for farmers. Option B is wrong because the issue price is the rate at which the Food Corporation of India sells grain to the States for the public distribution system. Option D is wrong because "fair sustenance price" is not an official price at all. Exam tip: MSP is recommended by the CACP and approved by the CCEA; sugarcane gets the FRP instead.

The correct answer is B, inflationary gap. When demand pushes the economy to produce more than it can at full employment, the extra demand only drives prices up. Full-employment GDP, also called potential GDP, is the output an economy can produce when all its resources are in use. If aggregate demand is so high that equilibrium real GDP sits above this level, the difference is the inflationary gap. Real output cannot keep rising beyond capacity, so the excess shows up as rising prices. The idea comes from J.M. Keynes, who used it in his 1940 pamphlet "How to Pay for the War", and the cure is to cut demand through higher taxes, lower government spending or tighter money. Option A is wrong because a recessionary gap is the opposite case, when equilibrium GDP falls short of full employment. Option C is wrong because the income multiplier measures how much income rises for each rupee of new spending. Option D is wrong because automatic stabilisers are tools, such as progressive taxes, that help narrow these gaps. Exam tip: output above potential is an inflationary gap; output below potential is a recessionary gap.

The correct answer is A, Personal income tax. A progressive income tax takes a bigger share when incomes rise and a smaller one when they fall, without any new decision by the government. Such tools are called automatic or built-in stabilisers, because they soften booms and slumps on their own. In a boom, rising incomes push people into higher tax slabs, so tax collections grow faster than income and cool down spending. In a recession, collections fall faster than income, which leaves more money in people's hands. Unemployment benefits work the same way on the spending side of the budget. Option B is wrong because the reverse repo rate is changed by the Reserve Bank of India through a deliberate policy decision, which makes it discretionary monetary policy. Option C is wrong because open market operations, the buying and selling of government securities by the RBI, are also a deliberate policy step. Option D is wrong because a bond price is a market outcome, not a policy tool. Exam tip: automatic stabilisers need no decision; progressive taxes and unemployment benefits are the classic pair.

The correct answer is C, Kolkata. Kolkata is the only major port of India built on a river, the Hooghly, about 200 km upstream from the sea. It became a Port Trust in 1870 and since 2020 has been named the Syama Prasad Mookerjee Port. It works as a twin system: the Kolkata Dock System handles smaller ships, while the Haldia Dock Complex, nearer the sea, takes larger ones. Silt carried by the river keeps the channel shallow, so constant dredging is needed, and the Farakka Barrage was built partly to push more Ganga water into the Hooghly to flush it. Option A is wrong because Mormugao is a natural harbour at the mouth of the Zuari in Goa, known for iron ore exports. Option B is wrong because Deendayal, earlier called Kandla, is a tidal port on the Gulf of Kutch in Gujarat. Option D is wrong because Paradip is a deep-water sea port on the Odisha coast. Exam tip: the only riverine major port is Kolkata on the Hooghly, with Haldia as its deep-water dock.

The correct answer is C, A-4, B-3, C-2, D-1. The Sutlej feeds the Indus, the Kosi the Ganga, the Teesta the Brahmaputra and the Chambal the Yamuna. The Sutlej rises near Rakas Tal close to Mansarovar in Tibet, enters India at Shipki La and is the easternmost of the five Punjab rivers of the Indus system; the Bhakra dam stands on it. The Kosi, called the "Sorrow of Bihar" for its floods and shifting course, joins the Ganga near Kursela in Bihar. The Teesta, the lifeline of Sikkim, crosses north Bengal into Bangladesh and meets the Brahmaputra there. The Chambal rises near Mhow in Madhya Pradesh, carves the famous ravines and joins the Yamuna in Etawah district of Uttar Pradesh. Option A is wrong because it links the Sutlej with the Yamuna and the Chambal with the Indus. Option B is wrong because it also pairs the Kosi with the Brahmaputra and the Teesta with the Ganga. Option D is wrong because it swaps the Kosi and the Teesta. Exam tip: Sutlej-Indus, Kosi-Ganga, Teesta-Brahmaputra, Chambal-Yamuna.

The correct answer is C, Oxbow lake. When a river cuts across the narrow neck of a loop and silt seals both ends, the old loop is left behind as a curved lake. Meanders form in the middle and lower course, where a river flows slowly over flat land, cutting its outer bank and building up its inner bank. Over time the neck of a loop grows thinner until a flood breaks through it and the river takes the shorter path. The abandoned bend is shaped like the U-shaped collar of an ox's yoke, which gives the lake its name; Kanwar Lake (Kabar Tal) in Bihar was left behind in this way by the Burhi Gandak. Option A is wrong because potholes are round holes drilled into a rocky bed by pebbles swirling in a fast upper-course stream. Option B is wrong because levees are raised banks of silt dropped along the river during floods. Option D is wrong because a flood plain is the wide flat land built by repeated floods, not a cut-off loop. Exam tip: meander plus cut-off gives an oxbow lake, a mark of the river's old stage.

The correct answer is A, Nizam Shahis : Bijapur. The Nizam Shahis ruled from Ahmadnagar; Bijapur belonged to the Adil Shahis. The Bahmani Sultanate, founded in 1347 by Alauddin Hasan Bahman Shah, broke up in the late 15th and early 16th centuries into five Deccan Sultanates: Ahmadnagar, Bijapur, Golconda, Bidar and Berar. Four of them joined hands to defeat Vijayanagara at the Battle of Talikota in 1565, while Berar stayed away. Each dynasty is named after the title of its founder, which makes the pairs easy to link. Option B is correctly matched because the Barid Shahis ruled Bidar, the last Bahmani capital. Option C is correctly matched because the Qutb Shahis ruled Golconda, famous for its fort and its diamond trade. Option D is correctly matched because the Imad Shahis ruled Berar, which Ahmadnagar annexed in 1574. Exam tip: Nizam Shahi Ahmadnagar, Adil Shahi Bijapur, Qutb Shahi Golconda, Barid Shahi Bidar, Imad Shahi Berar.

The correct answer is C, 3 only. Members of the State Legislative Councils have no vote in the presidential election. Under Article 54, the President is chosen by an electoral college of the elected members of both Houses of Parliament and the elected members of the Legislative Assemblies of the States. The 70th Amendment Act, 1992 added the elected members of the Assemblies of Delhi and Puducherry. Voting follows proportional representation by the single transferable vote, and the ballot is secret. Nominated members of any House and all members of Legislative Councils stay out, though nominated members of Parliament do vote for the Vice-President. Options A and D are wrong because the elected members of the Rajya Sabha and of the State Assemblies are both part of the electoral college. Option B is wrong because it leaves out the elected Assembly members too, when they cast about half of the total vote value. Exam tip: only elected members of Parliament and the Assemblies vote for the President; Council members and nominated members never do.