General Science Mixed Quiz: Set 131

Tritium gives out beta particles, not alpha particles, and a water molecule is bent, not linear, so these two statements are wrong.

The cerebellum lies behind and below the cerebrum and coordinates voluntary muscular activity, so it keeps the body balanced and the posture steady; damage to it causes a staggering walk even though the muscles are strong.

pH falls, not rises, as hydrogen ion concentration rises, so a more acidic solution has a lower pH. pH is defined as the negative logarithm of the hydrogen ion concentration: pH = −log[H⁺].

The 2011 FSSAI labelling rules made the list of ingredients, nutrition information and the vegetarian or non-vegetarian mark compulsory, but not medical advice on allergies.

Meristems are groups of actively dividing cells, and all new plant tissue comes from them. Meristematic cells are living, small and closely packed, with thin cellulose walls, dense cytoplasm, a large nucleus and few or no vacuoles.

Polythene, also written polyethene, is formed by the addition polymerisation of ethene, in which the double bond of each molecule opens and the units join into a long chain with nothing eliminated.

Typhoid is caused by the bacterium Salmonella typhi; the other three are viral diseases. Salmonella typhi spreads through food and water contaminated with the faeces of an infected person, which is why typhoid is common where sanitation is poor.

The British geneticist Alec Jeffreys developed DNA fingerprinting in 1984 by studying short repeated sequences that vary in number from person to person, and the method is now used in criminal investigation, in disputes about parentage and in identifying victims of accidents and disasters.

Photosynthesis gives off oxygen, and oxygen is what aerobic respiration needs to release energy from food. In photosynthesis, green plants use sunlight, carbon dioxide and water to make glucose, and release oxygen, which comes from the splitting of water.

This filarial roundworm causes elephantiasis, also called lymphatic filariasis. The adult worms live in the lymphatic vessels and block the flow of lymph, so the legs, arms or genitals swell and the skin thickens, giving the disease its name.

The retina is the light-sensitive layer at the back of the human eye; it is not a part of any microscope.

Pliers and scissors are each made of two arms joined at one rivet, and each arm is a complete class 1 lever, so the tool is called a double lever.

Because water is densest at 4°C, the bottom of a lake stays liquid and relatively warm while the surface freezes, so aquatic animals survive there.

The middle ear holds three tiny bones, the smallest in the human body, called the malleus, the incus and the stapes, which in everyday English are the hammer, the anvil and the stirrup.

A solid that does not vaporise stays behind when the solvent is removed, whether the solvent is boiled off or the solid is made to crystallise out.

The anode is the electrode joined to the positive terminal of the supply, so negatively charged ions, the anions, travel to it and give up electrons there; loss of electrons is oxidation.

Soap lowers the surface tension of water, so water spreads into fine gaps and wets greasy dirt that plain water would bead up on.

A simple microscope is just a convex (converging) lens of short focal length, held close to the eye, which gives an enlarged image of a small object.

Bronze is an alloy of copper and tin, usually about 88 parts copper to 12 parts tin. Adding tin makes copper harder, stronger and easier to cast, and bronze also resists corrosion well.

Carbon fibre is widely used in cars and aircraft for its strength and low weight, and it can be recovered and recycled.