Question

(a) What are genes? Where are they located in our body?
(b) What is meant by dominant genes and recessive genes? Give one example of each.
(c) Explain how, characteristics (or traits) are inherited through genes.

Answer 1

(a) Genes are units of heredity which transfer characteristics (or traits) from parents to their offsprings during reproduction. Genes are located on chromosomes.

(b) The gene which decides the appearance of an organism even in the presence of an alternative gene is known as dominant gene. The gene which can decide the appearance of an organism only in the presence of another identical gene is called a recessive gene. For example, in pea plants, the dominant gene for tallness is T and the recessive gene for dwarfism is t.

(c) Genes are responsible for the characteristic features of an organism. The characteristics or traits of parents are transmitted to their progeny through genes present on their chromosomes during the process of sexual recombination. There is a pair of genes for each characteristic of an organism. However, each parent passes only one of the two genes of the pair for each characteristic to its progeny through gametes. Thus, the male gamete and female gamete carry one gene for each characteristic form the gene pairs of parents. But when a male gamete fuses with a female gamete during fertilisation, they make a new cell called zygot,e with a full set of genes. This zygote grows and develops to form a new organism having characteristics from both the parents.