Biology Questions and Answers

Answer: A

Oxygen is carried by haemoglobin, the iron-containing protein of the red blood cells.

Each molecule holds four haem groups and so binds four oxygen molecules. Myoglobin, its relative, stores oxygen in muscle but does not transport it; keratin and collagen are structural proteins.

Answer: B

Genetic equilibrium is disturbed by a lack of random mating.

The Hardy-Weinberg principle holds only if mating is random and there is no mutation, migration, selection or genetic drift. Assortative mating or inbreeding changes the genotype frequencies at once, even where the allele frequencies stay the same.

Answer: B

The phase after metaphase is anaphase.

The order is prophase, metaphase, anaphase, telophase. In anaphase the centromeres divide and the spindle fibres pull the sister chromatids to opposite poles of the cell.

Answer: A

A virus multiplies only in living tissue.

It has no metabolism, no ribosomes and no means of making protein, so it must use a living host cell's machinery. This is why viruses cannot be grown on a culture medium as bacteria are, and are cultured in eggs or cell lines instead.

Answer: C

Phloem is a plant tissue. It carries the sugars made in the leaves to the rest of the plant, in both directions as needed.

Its conducting elements are sieve tubes, living cells whose end walls are perforated, assisted by companion cells. Xylem, the other vascular tissue, carries water upward only.

Answer: A

Monocarpic plants fruit once in their life and then die.

All annuals and biennials are monocarpic, as are some long-lived plants: bamboo may grow for decades before flowering once and dying. Polycarpic plants, such as most trees, fruit year after year.

Answer: A

The soil system is not a biotic component - it is abiotic.

Biotic components are the living ones: plants, animals and micro-organisms. Soil, water, air, light and temperature are the physical and chemical surroundings in which they live, though soil does of course contain living organisms.

Answer: D

All three - cadmium, asbestos and benzene - are carcinogens.

Asbestos fibres cause mesothelioma and lung cancer, benzene causes leukaemia, and cadmium is linked with lung and prostate cancer. All are classed as Group 1 human carcinogens by the IARC.

Answer: C

The peanut ripens its fruit underground.

After fertilisation the stalk beneath the flower elongates and pushes the young pod into the soil, where it matures - which is why it is also called the groundnut. Potato and onion are underground stems and carrot a root, not fruits.

Answer: B

Leukaemia is a disease of the blood - a cancer of the white cells.

The bone marrow produces immature white cells in enormous numbers, crowding out normal red cells and platelets, so the patient becomes anaemic, bleeds easily and cannot fight infection.