Biology Questions and Answers

Answer: C

Pathogenic bacteria grow fastest between about 20 and 45°C.

This is the danger zone for food, and it brackets body temperature, 37°C, which is where human pathogens are best adapted to grow. Refrigeration below 5°C slows them and cooking above 70°C kills them.

Answer: B

Epinephrine - adrenaline - is used to treat cardiac arrest.

It constricts the peripheral vessels, raising the pressure that drives blood to the heart and brain during compressions, and stimulates the heart itself. It is given intravenously during resuscitation.

Answer: C

Ranikhet disease, or Newcastle disease, is the commonest poultry disease in India.

It is a viral infection causing respiratory and nervous symptoms and can kill an entire flock. It is named after the Uttarakhand town where it was first reported in India in 1928, and is controlled by vaccination.

Answer: C

Fungi account for the largest number of species among these.

About 100,000 have been described and the true number is estimated in the millions, against perhaps 40,000 algae, 20,000 lichens and 25,000 mosses and ferns. Fungi are second only to insects among all groups of organisms.

Answer: C

In science either deductive or inductive reasoning, or both, may be used.

Induction generalises from observations into a hypothesis; deduction then draws from that hypothesis a prediction which can be tested. The two work together in the cycle of hypothesis and test.

Answer: D

The antibiotic will not help because you are infected by a virus.

Antibiotics work on structures and processes peculiar to bacteria - the cell wall, bacterial ribosomes, bacterial enzymes. A virus has none of these and replicates inside your own cells, so an antibiotic has nothing to act on. Most sore throats and colds are viral.

Answer: C

The flavour of apples is chiefly due to ethanal (acetaldehyde).

It is one of the volatile compounds released as the fruit ripens, along with esters such as ethyl butanoate. Formalin and benzaldehyde are quite different: benzaldehyde gives almonds their smell.

Answer: B

Palaeobotany is the study of plant fossils.

It reconstructs past vegetation and climates from fossil wood, leaves, pollen and spores, and provides much of the evidence for continental drift - the same fossil flora appearing on continents now far apart.

Answer: A

The incorrect statement is that platelets contain DNA.

They have no nucleus, being fragments budded off from megakaryocytes in the marrow. The rest is true: they are roughly disc-shaped, about 2 to 3 micrometres across against the red cell's 7, and synthesise very little protein.

Answer: D

Excess fluorine causes bone deformity.

Skeletal fluorosis follows years of drinking water with more than about 1.5 mg of fluoride per litre: the bones thicken, the ligaments calcify and the spine and limbs bend. It is endemic in parts of Rajasthan, Andhra Pradesh and Gujarat.