General Science Previous Year Questions (PYQ) with Answers – Page 10

A sphygmomanometer has an inflatable cuff wrapped around the upper arm, a rubber bulb to pump air into it, and a gauge, traditionally a column of mercury.

Vitamin B1 is the chemical called thiamin (also spelt thiamine), the first of the B-complex vitamins to be identified. Thiamin is a water-soluble vitamin that helps the body turn carbohydrates into energy and keeps nerves and the heart working properly.

By the Rayleigh criterion the smallest angle the eye can resolve is 1.22 times the wavelength divided by the diameter of the pupil, that is 1.22 multiplied by 500 nanometres and divided by 3 millimetres, which comes to about 2.03 times ten to the power minus four radian.

The two pathogens have been swapped: malaria is caused by Plasmodium and TB by Mycobacterium, so both pairs are wrong.

Only the female Anopheles bites humans for blood, and in doing so it passes the malaria parasite, Plasmodium, into the bloodstream.

The Scottish scientist discovered penicillin in 1928 at St Mary's Hospital in London. Fleming noticed that a mould, Penicillium notatum, had accidentally grown on a culture plate of Staphylococcus bacteria and had killed the bacteria around it.

Fibrinogen is a soluble plasma protein that is turned into insoluble fibrin threads, which form the mesh of a blood clot.

In the DNA double helix, adenine on one strand always pairs with thymine on the other, and guanine always pairs with cytosine.

Oxygen in the air reacts with the fats and oils, and the food turns rancid, with a bad smell and taste.

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

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

This statement is false: diamond is an electrical insulator because it has no free electrons. In diamond, every carbon atom uses all four of its valence electrons to form strong covalent bonds with four other carbon atoms in a rigid three-dimensional network.

When muscles run short of oxygen, the pyruvate formed from glucose is converted into lactic acid instead of being broken down fully.

Water gas is a mixture of carbon monoxide and hydrogen, made by passing steam over red-hot coke. The reaction is C + H2O → CO + H2, carried out at about 1,000 degrees Celsius.

Breaking lead nitrate into lead oxide, nitrogen dioxide and oxygen needs a steady supply of heat, so the reaction absorbs energy and is endothermic.

A Lewis acid is a species that accepts a pair of electrons, and all three of these can do so.

Dalton held that the atom is the smallest, indivisible particle of matter, so his theory cannot explain particles inside the atom.

Temporary hardness is caused by the bicarbonates (hydrogencarbonates) of calcium and magnesium dissolved in water. It is called temporary because it can be removed simply by boiling: on heating, the soluble bicarbonates break down into insoluble carbonates, or magnesium hydroxide, which settle out, and carbon dioxide escapes.

Rain water is the purest natural form of water because it is formed by evaporation and condensation, a natural distillation.

Germanium is a metalloid, an element whose properties lie between those of metals and non-metals. It is a hard, shiny, grey-white solid like a metal, yet it is brittle and conducts electricity far less well than a metal, which makes it a semiconductor.