Biology Questions and Answers

Answer: C

Only the conifers match the description.

They are about 500 of the 900 living gymnosperm species, over half the group, while the 250,000 angiosperms make the conifers a small fraction of seed plants as a whole - yet they dominate the northern forests.

Answer: C

Clove is a dried flower bud, of Syzygium aromaticum, picked before it opens.

Its aroma comes from eugenol, which makes up most of clove oil and is used as a local anaesthetic in dentistry. Cinnamon is bark, cardamom a fruit and coriander a seed.

Answer: B

Pyorrhoea is a disease of the gums - periodontitis, in which the gum recedes from the teeth and the pockets discharge pus.

It follows untreated gingivitis, destroys the bone supporting the teeth, and is the commonest cause of tooth loss in adults.

Answer: C

Bee venom is acidic, with a pH around 5.

Its main component is the peptide melittin. Wasp venom, by contrast, is slightly alkaline - which is the origin of the folk remedy of vinegar for wasp stings and baking soda for bee stings.

Answer: D

The study of fossils is palaeontology.

It reconstructs the history of life from preserved remains and traces, and supplies the direct evidence for evolution and for the sequence of geological time.

Answer: B

AIDS appears when HIV replicates rapidly in the helper T lymphocytes and destroys them.

The virus can lie latent for years while the CD4 count falls slowly. AIDS is diagnosed when the count drops below 200 per microlitre or an opportunistic infection appears - not on infection itself.

Answer: A

Lathyrism is caused by eating too much khesari dal, Lathyrus sativus.

Its neurotoxin, BOAA, damages the motor neurons of the spinal cord and paralyses the legs irreversibly. The pulse is drought-hardy and cheap, so it is eaten most where crops have failed.

Answer: D

Bending towards light is phototropism.

Auxin accumulates on the shaded side of the shoot tip, so cells there elongate more and the shoot curves towards the light. Geotropism is a response to gravity, thigmotropism to touch and chemotropism to chemicals.

Answer: B

Coconut oil is the option recorded here as gaining popularity for cooking in India.

Long the staple cooking medium of Kerala and coastal Karnataka, it has regained favour more widely as views on saturated fat have been revised; it is also stable at high temperature because it is highly saturated.

Answer: C

Agrostology is the study of grasses, from the Greek agrostis.

It matters far beyond lawns: the grass family includes every cereal - wheat, rice, maize, barley, oats - along with sugarcane and bamboo, and grasses cover about a fifth of the land surface.