General Science GK Questions with Answers – Page 68

Humans have a single functional insulin gene, INS, on the short arm of chromosome 11, and both chains of insulin come from it.

One nanometre is 10⁻⁹ metre, and since one metre is 100 (10²) centimetres, it equals 10⁻⁷ centimetre. The prefix nano means one billionth.

Saturated open-chain hydrocarbons are the alkanes, and every alkane fits the formula CₙH₂ₙ₊₂. In a saturated hydrocarbon every carbon atom is joined to others only by single bonds, so each carbon holds the largest possible number of hydrogen atoms.

Elephantiasis, or lymphatic filariasis, is an endemic disease: it stays steadily present in certain regions and develops slowly over years, rather than breaking out suddenly in a large number of people.

The spring constant is force divided by extension, so its SI unit is newton per metre. Hooke's law says that, within the elastic limit, the restoring force of a spring is proportional to how far it is stretched or compressed: F = −kx.

The wave travels at 1,200 m/s, so 2,400 m takes 2 seconds. The speed of any wave is the product of its frequency and wavelength: v = fλ.

All three are fungi that feed saprophytically: they release enzymes onto dead organic matter, digest it outside their bodies and then absorb the dissolved food.

The inner lining of the mouth and the oesophagus is made of squamous epithelium, so an injury to that lining damages this tissue.

Both are stored forms of glucose, but plants store it as starch and animals as glycogen. Starch and glycogen are polysaccharides, long chains of glucose units.

Genetic modification is used in plants, animals and microbes alike, so this statement is false. A genetically modified organism is one whose DNA has been changed, usually by taking a useful gene from one organism and putting it into another.

The chloride ion has 18 electrons, while the magnesium ion has only 10, so the two are not isoelectronic. Isoelectronic species have the same number of electrons.

Walls are whitewashed with a solution of slaked lime, calcium hydroxide, which is an inorganic compound; quicklime itself is not applied, and the shiny layer comes from Ca(OH)₂, not CaO.

Magnesium ribbon burns in air with a dazzling white flame, giving off heat and light and leaving a white powder of magnesium oxide.

An atomic clock keeps time by locking onto the fixed frequency of radiation that makes atoms such as cesium-133 or rubidium jump between two energy levels.

Lithium is so light that it floats on kerosene or paraffin oil, so it is kept coated in petroleum jelly or paraffin wax, or under an inert gas, instead of under oil.

A Van de Graaff generator is an electrostatic machine that builds up a very large static charge on a hollow metal sphere, raising it to millions of volts.

Starlight is bent again and again by layers of air of changing density, so its path and brightness keep shifting and the star seems to twinkle.

The focal length is 10 cm, and an object between F and C of a concave mirror gives a real image beyond C, in front of the mirror.

X-rays are electromagnetic waves made of photons, which carry no electric charge, so electric and magnetic fields cannot bend them.

Power equals force times velocity, so the force is 3,000 W divided by 5 m/s, which is 600 N. Power is the rate of doing work: P = W/t. Work is force times distance, W = F × d, so P = F × d/t, and since d/t is the…