Biology Questions and Answers

Answer: A

If blood becomes acidic, the oxygen-carrying capacity of haemoglobin decreases.

This is the Bohr effect: a fall in pH shifts the oxygen dissociation curve to the right, so haemoglobin releases oxygen more readily and binds it less. It is useful in the tissues, but in acidosis it means the lungs load less oxygen too.

Answer: B

The study of cells is cell biology, also called cytology.

It covers the structure, function and division of cells, and it became possible only with the microscope - Hooke named the cell in 1665 and Schleiden and Schwann framed the cell theory in 1838–39.

Answer: C

Tikka disease affects the groundnut.

It is a leaf spot caused by the fungi Cercospora; dark spots with yellow haloes spread over the leaves, which fall, and the yield drops sharply. It is the most damaging groundnut disease in India.

Answer: C

Biofuel is obtained from the seed of Jatropha.

The seeds are about 35 per cent oil, which is transesterified into biodiesel. The plant grows on poor land and does not compete with food crops, which is why India promoted it heavily, though yields have often disappointed.

Answer: A

Organisms that make their own food are autotrophs.

Photoautotrophs, such as green plants and cyanobacteria, use light; chemoautotrophs, such as the nitrifying bacteria, use energy from oxidising inorganic compounds. Everything else in the food chain depends on them.

Answer: A

Botany is also called phytology, from the Greek phyton, plant.

Phycology is the study of algae specifically, and pedology the study of soil.

Answer: D

Most bacteria reproduce by binary fission.

The chromosome is replicated, the two copies move apart, and the cell divides in two. It is asexual, so the daughters are genetically identical, and under good conditions a bacterium can divide every twenty minutes.

Answer: A

Starch is a polysaccharide - a polymer of hundreds or thousands of glucose units.

It occurs as amylose, an unbranched chain, and amylopectin, a branched one. It is the storage carbohydrate of plants; glycogen plays the same role in animals.

Answer: C

Cretinism is a disorder of the thyroid.

Deficiency of thyroxine from birth stunts both physical growth and mental development irreversibly. It is caused by iodine deficiency in the mother or by a failure of the child's own gland, and is now screened for in newborns.

Answer: C

The edible radish is a modified root - a swollen taproot storing food for the plant's second year.

Carrot, beetroot and turnip are the same kind of structure. A bulb is a compressed shoot with fleshy leaves, a corm a swollen stem base, and a tuber a swollen underground stem.