Biology Questions and Answers

Answer: D

X and Y are vitamins K and A.

Vitamin K is needed by the liver to make clotting factors such as prothrombin; its deficiency causes prolonged bleeding. Deficiency of vitamin A causes night blindness and xerophthalmia, in which the conjunctiva and cornea become dry and may ulcerate.

Vitamin \(B_{12}\) deficiency causes pernicious anaemia, vitamin C deficiency causes scurvy, and vitamin D deficiency causes rickets, so the other pairs are wrong.

Answer: D

The complete food is Milk.

Milk is called a complete food because it supplies almost all the nutrients the body needs: good-quality protein (casein and whey), fat, carbohydrate as lactose, minerals such as calcium and phosphorus, and most vitamins. It is the sole food of young mammals.

Pulses are rich in protein but poor in some amino acids and vitamins. Cereals are mainly sources of energy (starch). Leafy vegetables supply vitamins, minerals and fibre but little protein or energy. Milk is still low in iron and vitamin C, so the label is a broad one.

Answer: C

Mendel used Pisum sativum, the garden pea.

Gregor Mendel worked with the garden pea from 1856 to 1863 because it has clear contrasting characters (tall and dwarf, round and wrinkled seeds, and others), a short life cycle and flowers that normally self-pollinate but can be crossed by hand. His results gave the laws of segregation and independent assortment.

Solanum lycopersicum is the tomato and Triticum aestivum bread wheat. Pisum tuberosum mixes the pea genus with the potato's species name (Solanum tuberosum) and is not a real plant.

Answer: B

The capacity is totipotency.

Totipotency is the ability of a single plant cell or tissue piece (an explant) to divide and differentiate into a complete plant. It is the basis of plant tissue culture and micropropagation, in which whole plants are raised from small pieces of tissue on a nutrient medium.

Somatic hybridization is the fusion of protoplasts from two different plants, and hydroponics and aeroponics are ways of growing plants without soil, in nutrient solution or mist. None describes a cell's ability to form a whole plant.

Answer: B

People with blood group A have anti-B antibodies in their plasma.

In the ABO system, a person's red cells carry the antigens of their own group, and the plasma carries antibodies against the antigens they lack. Group A red cells carry antigen A, so the plasma has anti-B.

Anti-A would attack their own red cells, so it is found in group B. Both anti-A and anti-B are found in group O, and group AB has neither antibody.

Answer: B

The preserved traces of living organisms are called fossils.

Fossils are the remains or traces of organisms that lived long ago, preserved in rock: bones and shells, impressions of leaves, footprints and burrows. They are the main evidence for the history of life and for evolution.

A species is a group of organisms that can interbreed. A specimen is a single individual or sample collected for study. A skeleton is the supporting framework of an animal's body, which may or may not become a fossil.

Answer: C

The animals found both in water and on land are amphibians.

The word means 'double life'. Frogs, toads and salamanders typically lay eggs in water, and their larvae (tadpoles) live in water and breathe with gills. The adults develop lungs and can live on land, though they breathe partly through moist skin and return to water to breed.

Pisces (fishes) and Cyclostomata (lampreys and hagfishes) are aquatic throughout life. Reptilia are mainly land animals with dry scaly skin, and even turtles and crocodiles do not have the amphibians' two-stage life.

Answer: C

The acquired character is size of body.

An acquired character develops during an individual's lifetime because of the environment, food, exercise or use and disuse, and is not passed on through genes. Body size depends heavily on nutrition and activity: an underfed child stays small, and body weight changes with diet and exercise.

Colour of the eye, colour of the skin and the nature of the hair are inherited characters, decided by genes received from the parents. A suntan can darken the skin for a while, but the basic skin colour is inherited, which is why it is not the answer here.

Answer: B

The rules of inheritance were given by Gregor Mendel.

Gregor Johann Mendel, an Augustinian friar in Brno, crossed pea plants for several years and published his results in 1866. He showed that traits are passed on by discrete factors (now called genes) and set out the laws of dominance, segregation and independent assortment. He is called the father of genetics.

'Jesue', 'Bridge' and 'Jimmy' Mendel are not real scientists; they are invented names built around the surname, so the question tests only whether the first name is known.

Answer: C

Typhoid, cholera and anthrax are caused by bacteria.

• Typhoid: Salmonella Typhi.
• Cholera: Vibrio cholerae.
• Anthrax: Bacillus anthracis.

Viral diseases include measles, polio and influenza; fungi cause ringworm and candidiasis; protozoa cause malaria and amoebic dysentery. None of the three diseases in the question belongs to those groups, which is why they are treated with antibiotics.