RRB Group D GK Questions 2026

Cytokinins promote cytokinesis, that is cell division; kinetin was the first of them to be identified, from the degraded DNA of herring sperm, and zeatin, the natural form, was obtained from maize grains.

Jute is a bast or stem fibre taken from the inner bark of plants of the genus Corchorus, extracted by soaking the cut stems in water, a process called retting, and India and Bangladesh are the main producers.

Clove is the unopened flower bud of Syzygium aromaticum, picked before it blooms and dried, and it is grown in India chiefly in Kerala, Tamil Nadu and the Andaman and Nicobar Islands.

Quinine is an alkaloid extracted from the bark of trees of the genus Cinchona, native to South America and grown in India in the Nilgiris and in Darjeeling, and it was the standard treatment for malaria before synthetic drugs appeared.

Saffron is made from the stigmas of the flower of Crocus sativus, and since each flower carries only three stigmas which must be picked by hand, the spice is the most expensive in the world; in India it is grown mainly in the Kashmir valley.

2,4-dichlorophenoxyacetic acid is a synthetic auxin, and when it is sprayed in a heavy dose it throws broad-leaved dicot weeds into uncontrolled growth that kills them, while narrow-leaved cereals such as wheat and rice are far less affected, so it clears weeds from a standing crop.

Auxin made at the shoot tip moves downwards and keeps the lateral buds below it inactive, which is why a gardener who nips off the tip of a hedge plant gets a bushy growth of side branches.

Japanese rice plants attacked by this fungus grew abnormally tall and spindly, a condition called the foolish seedling or bakanae disease, and the substance responsible was isolated from the fungus and named gibberellin; gibberellic acid is the best known member of the group.

It is produced when a plant faces drought, salinity or extreme temperature; it closes the stomata so that water is not lost, for which reason it is called an antitranspirant, and it induces dormancy in seeds and buds so that growth waits for better conditions.

Ethylene is the only gaseous plant hormone, and it raises the rate of respiration in climacteric fruits such as banana, mango and tomato, so a single ripe fruit speeds up the ripening of those around it; the compound ethephon releases ethylene and is used in orchards for uniform ripening.

An anemometer measures how fast the wind is blowing; its name comes from the Greek word anemos, meaning wind.

Light that enters a cut diamond is reflected again and again inside it before it escapes, which makes the stone sparkle.

Sound is a mechanical wave that needs a medium to travel, while the other three are electromagnetic waves. Sound travels as a longitudinal wave of compressions and rarefactions in air, water or solids, which is why it cannot pass through a vacuum.

The normal human ear hears sound from about 20 hertz to 20,000 hertz, the audible range. Frequency, measured in hertz, is the number of vibrations per second, and it decides the pitch of a sound: the higher the frequency, the shriller the note.

Ultrasound is sound with a frequency above 20,000 Hz, the upper limit of human hearing. Humans hear sound between about 20 Hz and 20 kHz.

Propane is a light gaseous hydrocarbon that burns completely with a blue flame, leaving no smoke, soot or ash. A clean fuel burns completely, gives high heat and releases few pollutants.

Soft soaps are potassium salts of fatty acids, while ordinary hard bar soaps are sodium salts. Soap is made by saponification, heating an oil or fat with an alkali.

Magnesium, calcium and barium are all alkaline earth metals of group 2, and each has a valency of 2. Elements in the same group of the periodic table have the same number of electrons in their outermost shell, and so the same valency.

Their valencies are neon 0, magnesium 2, nitrogen 3 and silicon 4. Valency is the combining capacity of an atom, the number of electrons it loses, gains or shares to reach a stable octet.

Electric power is P = V × I, and 220 V × 0.6 A = 132 W. Power is the rate at which electrical energy is used, measured in watts; one watt is one joule per second, or one volt times one ampere.