General Science Questions and Answers

Answer: C

A virus carries either DNA or RNA as its genetic material, never both.

This is one of the features that separates viruses from cells, which all contain both. The distinction gives the two great classes of viruses - DNA viruses such as herpes and RNA viruses such as influenza and HIV.

Answer: D

Ichthyology is the study of fish, from the Greek ichthys, fish.

Herpetology covers snakes and lizards, and ornithology covers birds.

Answer: D

Viruses are total (obligate) parasites. They have no metabolism, no ribosomes and no means of making energy or protein, so they can reproduce only inside a living host cell.

Outside a host a virus is an inert particle. This is why viruses are often described as being on the boundary between living and non-living.

Answer: B

Cocci are the smallest bacteria in shape and size - spherical cells typically about 0.5 to 1 micrometre across.

Bacilli are rod-shaped, vibrios comma-shaped and spirilla spiral, and all three are longer than a coccus is wide.

Answer: C

Pulses are rich in protein because their roots carry nodules containing Rhizobium bacteria, which fix atmospheric nitrogen into a form the plant can use.

Protein is built from nitrogen-containing amino acids, so this private nitrogen supply lets legumes make far more protein than other crops - and enriches the soil for whatever is sown next.

Answer: D

Ethylene is used to ripen fruit artificially. It is the plant's own ripening hormone, and treating harvested mangoes, bananas or tomatoes with a small concentration of it starts the process.

This is why fruit is picked and shipped unripe and gassed on arrival. Calcium carbide, which releases acetylene, is used illegally for the same purpose and is unsafe.

Answer: B

Wheat is not a millet. It is a cereal of the genus Triticum, grown as a rabi crop on good soil with assured moisture.

Ragi (finger millet), bajra (pearl millet) and jowar (sorghum) are all millets - small-grained, drought-hardy cereals grown on poor soils where wheat and rice will not survive.

Answer: C

Reserpine, the classic drug for high blood pressure, comes from Rauwolfia serpentina - sarpagandha - whose root has been used in India for centuries.

Digitalis yields the heart drug digoxin, cinchona yields quinine for malaria, and Papaver, the opium poppy, yields morphine.

Answer: A

Saffron is obtained from the styles and stigmas of Crocus sativus. Each flower yields just three stigmas, picked by hand, so about 150,000 flowers are needed for a kilogram - which makes it the most expensive spice in the world.

Asafoetida comes from a root resin, fennel from the seed and turmeric from the rhizome.

Answer: A

Ethyl mercaptan (ethanethiol, C₂H₅SH) is a compound of sulphur, added to LPG to give it a smell.

LPG is odourless, so a leak would otherwise go unnoticed until it reached an explosive concentration. The human nose detects mercaptan at a few parts per billion.