General Science GK Questions with Answers – Page 109

A concave lens is a diverging lens, so for every position of a real object it forms an image that is virtual, erect and diminished.

Acoustics is the branch of physics that deals with how sound is produced, how it travels and how it is heard or absorbed.

Drosera, known as the sundew, is an insect-eating plant whose leaves are covered with stalked glands tipped with a shining drop of sticky fluid.

In the colour code used for fire extinguishers, a black band or label marks a carbon dioxide extinguisher. The body of the cylinder is signal red and a coloured patch near the label tells you the filling at a glance, so the right cylinder can be picked in a hurry.

Fires are sorted into classes by what is burning, and Class A covers ordinary solid fuels — wood, paper, cloth, straw, rubber and many plastics.

Crown gall is caused by the bacterium Agrobacterium tumefaciens, which enters through a wound near the base, or crown, of the stem and makes the plant grow rough tumour-like swellings there.

The pulmonary artery is the one artery in the body that carries deoxygenated blood. It leaves the right ventricle and takes blood that has returned from the body's tissues to the lungs, where carbon dioxide is given up and fresh oxygen is picked up.

Animal tissues are grouped into four kinds — epithelial, muscular, connective and nervous — and areolar is not one of them, because it is only a type of connective tissue.

A wet chemical extinguisher sprays a fine mist of a potassium salt solution — usually potassium acetate, potassium citrate or potassium carbonate — so potassium is the working element inside it.

The domestic goat is treated as a subspecies of the wild goat, so its name carries three parts — the genus Capra, the species aegagrus and the subspecies hircus.

The alveoli are the tiny balloon-like air sacs at the ends of the smallest airways, and their thin walls are the surface where gases are exchanged.

Pressure counted from a perfect vacuum as the zero point is called absolute pressure. A perfect vacuum holds no gas and exerts no pressure, so it is the true zero of any pressure scale.

The hepatitis B vaccine was the first vaccine made by recombinant DNA technology.

A planimeter measures the area of any flat shape, however irregular its outline. The user simply traces the boundary of the shape on the map with the instrument's pointer, and a wheel and dial record the area swept, which is then multiplied by the square of the map scale.

High-speed steel is named 18-4-1 after the three metals added to it in that order: 18 per cent tungsten, 4 per cent chromium and 1 per cent vanadium, with iron making up the rest along with a little carbon.

Adrenaline, also called epinephrine, is made by the medulla of the adrenal gland and is the body's emergency hormone; it makes the heart beat faster and stronger and narrows the small blood vessels, so blood pressure rises within seconds.

Ashwagandha, whose botanical name is Withania somnifera, is called winter cherry in English because of the small red berry it bears inside a papery cover; it is also called Indian ginseng.

In human beings the sperm meets and fuses with the egg inside the fallopian tube, also called the oviduct. The ovary releases one egg in a month, and the funnel shaped mouth of the fallopian tube collects it.

Hydra, starfish and planaria can all grow a lost or cut off part of the body back into a whole animal, and that ability is called regeneration.

Hydra is the one animal in the list that reproduces both by budding and by regeneration. In budding, a bulge grows out from the body wall of the parent Hydra, develops a mouth and tentacles, and then breaks off as a small independent Hydra.