CDS GK Questions 2026

Jatropha curcas yields a non-edible oil seed, and because India cannot spare edible oil for fuel, the National Policy on Biofuels looks to non-edible oils such as Jatropha and Pongamia pinnata, or karanja, along with used cooking oil and animal tallow, as feedstock for biodiesel.

In transesterification a vegetable oil or animal fat is made to react with methanol or ethanol in the presence of an alkaline catalyst such as potassium hydroxide, giving fatty acid methyl esters, which are biodiesel, and glycerol as the by-product.

Biogas is produced by the anaerobic digestion of organic matter, and methane is its largest component, roughly half to three quarters of the gas by volume; this is what makes biogas combustible.

SATAT stands for Sustainable Alternative Towards Affordable Transportation and was launched in October 2018 by the Ministry of Petroleum and Natural Gas; under it the oil marketing companies invite entrepreneurs to set up compressed bio-gas plants from agricultural residue, cattle dung and municipal waste and offer to buy the gas…

Second generation biofuels are made from lignocellulosic biomass that is not food, such as paddy straw, wheat straw, bagasse, cotton stalk and municipal solid waste; the cellulose must first be broken down into fermentable sugars, which makes the process costlier and earns these fuels the name advanced biofuels.

Ethanol is the two carbon alcohol obtained by the fermentation of sugars by yeast, and it is the alcohol blended into petrol under the Ethanol Blended Petrol programme.

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.

Roots take up nitrogen chiefly as the nitrate ion and to a smaller extent as ammonium; inside the plant the nitrate is reduced and built into amino acids, proteins and nucleic acids.

Carbon dioxide is a trace gas, roughly four hundredths of one per cent of dry air by volume, yet it is the source of all the carbon that photosynthesis fixes into food and the chief gas by which human activity is warming the planet.