RRB Group D GK Questions 2026

Pyruvic acid formed in glycolysis enters the mitochondrion, is converted to acetyl coenzyme A and is oxidised completely in the matrix through the cycle named after Hans Krebs, who received the Nobel Prize for the discovery; the cycle releases carbon dioxide and reduced coenzymes.

Glycolysis, also called the Embden Meyerhof Parnas pathway, splits one molecule of glucose into two molecules of pyruvic acid in the cytoplasm, needs no oxygen and gives a net gain of two ATP along with two molecules of reduced NAD.

Ganong's potometer and the simpler bubble potometer measure the water absorbed by a cut shoot in a given time, and since almost all of that water is lost as vapour, the reading is taken as the rate of transpiration.

In light, potassium ions are actively pumped into the guard cells, their solute concentration rises, water enters by osmosis, the cells swell and because their inner walls are thicker they bend apart, opening the pore; when potassium leaves, the cells lose water and the pore closes.

Its sieve tubes, helped by companion cells, carry sucrose and other soluble food from a source such as a mature leaf to a sink such as a root, fruit or bud, and the movement can be upward or downward.

It occurs through pores called hydathodes at the leaf margin or tip, usually in the early morning when the soil is moist, the air is humid and transpiration is low, so root pressure forces out drops of water with dissolved salts; Colocasia, grasses and tomato show it well.

Dixon and Joly explained that water molecules cling to one another by cohesion and to the xylem walls by adhesion, forming an unbroken column; evaporation from the leaf surface creates a suction at the top that pulls this column upward.

Caesium melts at about 28.5 °C, the lowest of these alkali metals, so it can turn liquid on a warm day or in the hand.

The girth, or thickness, of a stem increases only through the lateral meristems, the vascular cambium and the cork cambium.

The gastric glands in the stomach wall secrete pepsin, which begins the digestion of proteins into smaller peptides. The chief cells of the gastric glands release pepsin in an inactive form, pepsinogen.

The blue colour comes from water of crystallisation: blue vitriol is CuSO4·5H2O, and heating drives off these five water molecules to leave white anhydrous copper sulphate.

Zinc lies in the middle of the reactivity series, so its oxide can be reduced to the metal by heating it with carbon (coke): ZnO + C → Zn + CO.

This is false: aluminium has three electrons in its outer shell and loses all three, so its valency is 3.

Cambium lies along the sides of stems and roots and its dividing cells increase their thickness, which is the work of a lateral meristem.

Sodium hydroxide dissolves in water and splits completely into Na+ and OH- ions; the ions carry current and the hydroxide ions make the solution strongly basic.

Powers of lenses in contact simply add, so the combination has a power of 2 + 2 = 4 dioptre, and its focal length is 1/4 m, that is 0.25 m. The power of a lens is the reciprocal of its focal length in metres, P = 1/f, and is…

Parenchyma is the basic packing tissue of plants, and it is also present in both xylem (xylem parenchyma) and phloem (phloem parenchyma).

Oxidising power of the halogens falls as we go down group 17, so iodine is the weakest and fluorine the strongest oxidising agent.

Urea, CO(NH2)2, contains about 46 per cent nitrogen, the highest of any common solid fertiliser, and is the main nitrogen fertiliser used in India.

The primary structure of a protein is simply the linear order of amino acids joined one after another by peptide bonds.