Defence Previous Year GK Questions with Answers

The correct answer is B, mitochondria and plastids. Both carry a small circular DNA of their own and their own 70S ribosomes, so they make a part of their protein themselves and divide independently of the cell; this semi-autonomous nature is the main evidence for the view that they descend from free-living bacteria engulfed by an early cell. Option A is wrong because the Golgi body and the endoplasmic reticulum are membrane systems that modify and transport material and carry no genetic matter of their own; the rough endoplasmic reticulum merely holds ribosomes on its outer surface. Option C is wrong because the lysosome is only a sac of digestive enzymes and the Golgi body, as stated, has no DNA. Option D is wrong because the vacuole is a storage sac bounded by the tonoplast and has no DNA, even though its partner in the option, the plastid, does. Remember the pair as the two power organelles of the cell.

The correct answer is D, all four. A bicameral State legislature has a Legislative Assembly and a Legislative Council, and Andhra Pradesh, Telangana, Bihar and Uttar Pradesh each have both Houses. Options A, B and C are wrong because each of them leaves out a State that does have a Council. Bihar has had a Council since before independence and Uttar Pradesh is the largest of the bicameral States; Andhra Pradesh revived its Council by an Act of Parliament, and Telangana received one when it was carved out of Andhra Pradesh in 2014. The Governor is central to this arrangement: under Article 168 he is part of the legislature, under Article 171 he nominates one-sixth of the Council, and under Article 169 no Council can be created or abolished unless the Assembly passes a special-majority resolution and Parliament then makes a law.

The correct answer is C, Telangana. The Kaleshwaram project lifts water from the Godavari near the confluence of the Godavari and the Pranahita and carries it through a chain of barrages, pump houses, tunnels and canals to the drier districts of Telangana; it is described as a multi-stage lift irrigation scheme rather than a single storage dam. Option A is wrong because Kerala’s largest irrigation and power works are on the Periyar, such as the Idukki arch dam. Option B is wrong because Gujarat’s major project is the Sardar Sarovar on the Narmada. Option D is wrong because Maharashtra’s best-known works are Koyna on the Koyna river and Ukai lies in Gujarat on the Tapi. For this topic remember the pairing of state, river and type of structure, since that is exactly what the question tests.

The correct answer is D, Polarization. Only a transverse wave can be polarised, so the polarisation of light proves that its vibrations are at right angles to the direction of travel. In ordinary light the electric field vibrates in every plane around the ray. A polaroid sheet lets through only the vibrations in one plane, and a second polaroid turned at ninety degrees then blocks the light completely. A longitudinal wave such as sound, whose particles vibrate along the direction of travel, has no such plane and can never be polarised. Sunglasses, camera filters and LCD screens all use this property. Option A is wrong because refraction, the bending of light on entering a denser medium, happens with sound waves too. Option B is wrong because diffraction, the spreading of a wave at an edge, is shown by all waves. Option C is wrong because interference only proves that light is a wave, not which kind. Exam tip: interference and diffraction prove light is a wave; polarisation proves it is a transverse wave.

The correct answer is C, a mechanism to reduce CO2 emission. A nuclear reactor splits heavy atoms; it burns no fuel, so it releases no carbon dioxide and needs no equipment to cut such emissions. The heat of fission is produced in the reactor core, carried away by a coolant, passed to water in a heat exchanger or steam generator, and the steam then turns a turbine coupled to a generator. Control rods of cadmium or boron absorb spare neutrons and a moderator such as heavy water slows them down so that fission continues steadily. Option A is wrong as a choice because the turbine is the part that actually converts steam energy into electricity. Option B is wrong because the heat exchanger carries heat from the radioactive coolant loop to the clean water loop. Option D is wrong because the reaction chamber, the core holding the fuel rods, is where fission happens. Exam tip: a nuclear plant emits no carbon dioxide; its waste problem is spent radioactive fuel instead.

The correct answer is C, because the Suez Canal has no locks at all. It is a sea level canal: the Mediterranean and the Red Sea stand at almost the same height, so ships sail straight through without being raised or lowered. The canal, about 193 km long, was built under Ferdinand de Lesseps and opened in November 1869 across the Isthmus of Suez in Egypt, separating Africa from Asia. Egypt nationalised it in 1956. Options A, B and D all state facts, so none of them is the answer: the canal did open in 1869, it does join the Mediterranean to the Red Sea through the Gulf of Suez, and it did shorten the voyage from Europe to India by thousands of kilometres, ending the long route round the Cape of Good Hope. Exam tip: Suez is a lock free canal; the Panama Canal is the one with locks, because Gatun Lake lies well above sea level.

The correct answer is B, Cytoplasm. Bacteria are prokaryotes, so their DNA lies free in the cytoplasm instead of being packed inside a nucleus. The single circular chromosome sits in a region of the cytoplasm called the nucleoid, which has no nuclear membrane around it. Many bacteria also carry small extra rings of DNA called plasmids, which often hold genes for antibiotic resistance and are the tools used to move genes in biotechnology. Option A is wrong because a true nucleus with a membrane is found only in eukaryotes such as plants, animals and fungi; bacteria have no such organelle. Option C is wrong because the cell membrane only controls what enters and leaves the cell, although the chromosome is loosely attached to it at one point. Option D is wrong because ribosomes, of the smaller 70S type in bacteria, build proteins from the instructions in the DNA and store no genetic material themselves. Exam tip: prokaryotes have a nucleoid and 70S ribosomes; eukaryotes have a true nucleus and 80S ribosomes.

The correct answer is A, it proposed that the Indian magistrates would try Europeans in criminal cases. The Ilbert Bill of 1883 sought to remove the rule that European British subjects could be tried only by European judges. It was drafted by Sir Courtenay Ilbert, the law member of Lord Ripon’s council, and would have let Indian district magistrates and sessions judges hear criminal cases against Europeans. The European community in India protested so fiercely that the bill was watered down in 1884, giving a European the right to be tried by a jury half of whose members were European. The episode taught educated Indians the value of organisation and is counted among the immediate causes of the founding of the Indian National Congress in 1885. Option B is wrong because Indians could already file such cases. Option C is wrong because the bill spoke of Indian judges and magistrates generally, not of ICS officers alone. Option D is wrong because Ilbert wrote the bill; the agitation was against it. Exam tip: Ilbert Bill 1883, Lord Ripon, and the Congress in 1885.

The correct answer is D, V D Savarkar. Vinayak Damodar Savarkar founded Abhinav Bharat at Nashik in 1904, together with his brother Ganesh. It grew out of an earlier group called Mitra Mela and took its name from Mazzini’s Young Italy, whose biography Savarkar translated into Marathi. The society trained young men in arms, spread revolutionary literature and had branches in Maharashtra and later in London, where Savarkar went on a scholarship and wrote The Indian War of Independence 1857. It was finally disbanded in 1952. Option A is wrong because Khudiram Bose was a young Anushilan Samiti revolutionary hanged in 1908 for the Muzaffarpur bomb case. Option B is wrong because Shyamji Krishna Verma founded the India House and the Indian Home Rule Society in London in 1905. Option C is wrong because Lala Har Dayal led the Ghadar Party, started in San Francisco in 1913. Exam tip: Abhinav Bharat 1904 Savarkar, India House 1905 Shyamji Krishna Verma, Ghadar Party 1913 Har Dayal.

The correct answer is A, Sodium bicarbonate (Sodium hydrogen carbonate). Baking soda is sodium hydrogen carbonate, NaHCO3, a mild base made by the Solvay process from brine, ammonia and carbon dioxide. On heating, or on meeting an acid such as the tartaric acid in baking powder, it gives off carbon dioxide, and it is these bubbles that make bread and cake rise. The same reaction makes it useful in soda acid fire extinguishers and as an antacid, since it neutralises excess hydrochloric acid in the stomach. Option B is wrong because sodium carbonate, Na2CO3, is washing soda, a much stronger base used for cleaning and in glass making. Option C is wrong because potassium bicarbonate is a different salt, used in some fire extinguishers and fertilisers, not in the kitchen. Option D is wrong because potassium carbonate is potash, used in soap and glass. Exam tip: baking soda NaHCO3, washing soda Na2CO3.10H2O, caustic soda NaOH, and bleaching powder Ca(OCl)Cl.

The correct answer is A, strength of the intermolecular forces of attraction. Melting means breaking the particles free of the forces holding them in a fixed lattice, so a higher melting point means stronger forces of attraction. Heat supplied at the melting point does not raise the temperature at all; it is used as latent heat of fusion to overcome those attractions. This is why ionic solids such as common salt melt near 800 degrees Celsius while wax, held together by weak forces, melts in the warmth of a hand. Option B is wrong because repulsive forces act only when particles are pushed very close and they do not hold a solid together. Option C is wrong because molecular mass is a poor guide, as heavy iodine melts far below lighter silica. Option D is wrong because size matters only through the strength of the forces it creates, not on its own. Exam tip: stronger intermolecular forces mean a higher melting point and a higher boiling point together.

The correct answer is A, Asia. Asia takes the largest share of India’s exports, close to half of the total, far ahead of any other continent. The reason is geography and trade policy together: India’s biggest regional markets are its own neighbourhood and West Asia, where the United Arab Emirates, Singapore, Bangladesh, China and Saudi Arabia buy petroleum products, engineering goods, gems and jewellery, rice and pharmaceuticals. Short shipping routes, free trade agreements with ASEAN and a large Indian diaspora in the Gulf all add to the flow. Option B is wrong because Europe is the second largest destination region but well behind Asia. Option C is wrong because Africa, though a growing market for Indian medicines and vehicles, takes only a small share. Option D is wrong because North America is dominated by the United States, which is India’s largest single export partner, yet one country cannot outweigh a whole continent. Exam tip: by continent it is Asia, by country the United States; the two facts are asked in exactly this way.

The correct answer is A, James Chadwick. Chadwick discovered the neutron in 1932 and won the Nobel Prize in Physics for it in 1935. He bombarded beryllium with alpha particles and found that the radiation given off was not affected by electric or magnetic fields, yet could knock protons out of paraffin. The only explanation was a particle with no charge and a mass close to that of the proton, which he named the neutron. It completed the picture of the atom, since the nucleus had earlier been short of mass, and it later made nuclear fission possible. Option B is wrong because Rutherford discovered the nucleus through his gold foil experiment and is credited with the proton. Option C is wrong because J. J. Thomson discovered the electron in 1897 with his cathode ray tube. Option D is wrong because John Dalton gave the atomic theory in 1803, long before subatomic particles were known. Exam tip: Thomson for the electron, Rutherford for the proton and nucleus, Chadwick for the neutron.

The correct answer is A, Bryophytes. Bryophytes live on land but still need water to complete reproduction, so they are called the amphibians of the plant kingdom. Mosses, liverworts and hornworts belong here. They grow in damp, shady places, have no true roots, stems or leaves and no vascular tissue, so water moves through them by simple absorption. Their male gametes swim to the egg through a film of water, which ties them to moist ground exactly as frogs are tied to ponds. Option B is wrong because thallophytes are the algae, mostly water plants that never left water. Option C is wrong because pteridophytes, the ferns, are the first plants with true vascular tissue, xylem and phloem. Option D is wrong because gymnosperms such as pine and cycas bear naked seeds and use pollen, not swimming gametes. Exam tip: bryophytes are amphibians of the plant kingdom, pteridophytes are the first vascular plants, and gymnosperms are the first seed plants.

The correct answer is A, the air pressure is less. A liquid boils when its vapour pressure equals the pressure of the air pressing on its surface, so lower air pressure means a lower boiling point. At sea level the atmosphere presses with about 101 kilopascals and water boils at 100 degrees Celsius. On a hill station the column of air above is shorter, the pressure falls, and water may boil at 90 degrees or less, which is why rice and pulses cook slowly in the mountains and a pressure cooker, which raises the pressure inside, is used to cook them faster. Option B is wrong because the surrounding temperature only decides how long heating takes, not the temperature at which boiling begins. Option C is wrong because the latent heat of vaporisation is a property of water and does not shrink with altitude. Option D is wrong because option A already states the correct reason. Exam tip: boiling point rises with pressure and falls with altitude; that single rule explains both the cooker and the hill station.

The correct answer is B, Cones. Cones are the photoreceptor cells of the retina that respond to colour in bright light. The human retina carries two kinds of photoreceptors. Cones number about six to seven million, sit densely near the centre of the retina and come in three types, sensitive to red, green and blue light; the brain mixes their signals into every shade we see. They work only when the light is good, which is why colours fade at dusk. Option A is wrong because rods are far more numerous but work in dim light and give only shades of grey, not colour. Option C is wrong because the blind spot is the point where the optic nerve leaves the eyeball and carries no photoreceptors at all. Option D is wrong because the fovea is a small pit in the retina, a place rather than a cell type, although it is packed with cones. Exam tip: rods for night and grey, cones for colour and daylight; colour blindness is a defect of the cones.

The correct answer is Chola Empire. The Sengol is a gold-plated silver sceptre topped by a figure of Nandi. In the Chola tradition, a new king received such a sceptre from a high priest as a symbol of the transfer of power and of the ruler's duty to govern justly. On 14 August 1947 priests from the Thiruvaduthurai Adheenam in Tamil Nadu presented a Sengol to Jawaharlal Nehru, and it was later kept in a museum in Allahabad. On 28 May 2023, when the new Parliament building was inaugurated, it was installed beside the Speaker's chair in the Lok Sabha.

The Pandyan option is the cleverest distractor, because the Pandyas were also a great Tamil dynasty, but the Sengol tradition invoked in 2023 was that of the Cholas. The Gupta and Shunga empires ruled in north India and have no link to it. Questions on the new Parliament building also ask its date of inauguration (28 May 2023) and the first bill passed in it, the Women's Reservation Bill of 2023.

The correct answer is B, light travels much faster than sound. The flash and the clap are produced at the same instant by the same discharge. Light covers about three lakh kilometres in one second, so it reaches the observer almost immediately, while sound in air covers only about 340 metres in a second and takes roughly three seconds for each kilometre. The gap between seeing and hearing is therefore a direct measure of distance.

Option A reverses the true order and would make thunder arrive first, which never happens. Option C is wrong because equal speeds would make the flash and the clap arrive together, with no gap at all. Option D confuses brightness with speed; the flash is indeed very bright, but intensity has nothing to do with why it arrives earlier, and even a faint flash would still be seen before the sound was heard.

The correct answer is B, the amplitude of the sound waves. Amplitude is the maximum displacement of a particle of the medium from its rest position, and the energy carried by a wave increases with the square of the amplitude. A larger amplitude therefore delivers more energy to the ear and is heard as a louder sound. Loudness is measured in decibel.

Option A, the velocity of the wave, is fixed by the medium and its temperature; a loud and a soft sound in the same room travel at exactly the same speed. Option C, frequency, decides pitch, that is whether the sound is shrill or flat, and not how loud it is; turning up the volume of a ringtone does not change its frequency. Option D combines two quantities that both govern properties other than loudness, so it is wrong for the same reasons.

The correct answer is D, 2 s. Convert the units first: 1 kilohertz is 1000 hertz and 50 centimetres is 0.5 metre. The speed is frequency multiplied by wavelength, that is 1000 multiplied by 0.5, which gives 500 metres per second. Time equals distance divided by speed, so 1000 metres divided by 500 metres per second gives 2 seconds.

Option A, 5 s, would follow from using a speed of 200 metres per second. Option B, 4 s, corresponds to a speed of 250 metres per second, which arises if the wavelength is halved by mistake. Option C, 3 s, is close to the time sound actually takes to cover a kilometre in ordinary air, about 340 metres per second, and is the trap for candidates who use the remembered speed of sound instead of the speed calculated from the data given.