Biology Questions and Answers

Answer: A

Veins carry blood back to the heart.

The pressure in them is low, so they have thin walls and rely on the squeezing of surrounding muscles to move the blood, with one-way valves to stop it flowing back. Arteries carry blood away from the heart at high pressure.

Answer: A

August Weismann challenged Lamarck's theory of the inheritance of acquired characters.

His germ plasm theory held that the reproductive cells are set apart early and unaffected by what happens to the body. He cut the tails off mice for twenty-two generations, and every litter was born with a full tail.

Answer: B

Insect-pollinated flowers have pollen that is rough and sticky, often with spines or a sticky coating, so it clings to a visiting insect.

Wind-pollinated pollen is the opposite: small, smooth, dry and light, produced in enormous quantity so that a little of it reaches a stigma by chance.

Answer: D

Plants take their nutrients mainly from the soil - nitrogen, phosphorus, potassium and the micronutrients, absorbed in solution through the root hairs.

Light supplies energy and chlorophyll captures it, but neither is a nutrient; the carbon comes from the air as carbon dioxide.

Answer: B

Global warming is controlled by reducing deforestation and cutting the use of fossil fuel.

Forests absorb carbon dioxide, so clearing them both releases stored carbon and removes the sink. Fossil fuels are the largest source of the emissions themselves.

Answer: D

Vitamin C hastens the healing of wounds.

It is required to hydroxylate proline in the making of collagen, the protein that gives new tissue its strength. Without it wounds fail to close and old scars break down - the classic sign of scurvy.

Answer: A

Wooden doors swell in the rains because of imbibition.

Cellulose and the other colloids of wood absorb water and swell, and the pressure they generate is enormous - enough to split rock, which is how stone was once quarried with dry wooden wedges.

Answer: B

Proving theories are true is not part of the scientific process.

Evidence can refute a theory but never prove it, since the next observation may contradict it. A theory that survives repeated attempts to refute it is provisionally accepted, not established.

Answer: A

Spices lose their flavour on prolonged boiling because their essential oils evaporate readily.

The aroma of a spice is carried by volatile oils, which vaporise with the steam. This is why spices are added towards the end of cooking, or fried briefly in fat, which holds the oils better than water.

Answer: C

The edible part of garlic is the fleshy scale leaves.

The bulb is a compressed stem, and each clove is a swollen scale leaf storing food. Onion is the same kind of structure with concentric rather than separate scales.