Question

42. (1) Write the differences between homologous organs
and analogous organs.
(ii) Write the differences between the sex chromo-
somes of man and sex chromosomes of woman.
(iii) Sex of a child is determined by the father. How? 4​

Answer 1

(i) Homologous organs

• These organs have the same structure or origin but perform different function
• They show divergent evolution
• Example: hands of human and fore-limbs of a frog

Analogous organs

• These organs have different structure or origin but perform same function
• They show convergent evolution
• Example: Both the wings of a butterfly and wings of a bird are used for same function i.e flying.

(ii) Difference between male chromosome and female chromosome

Male chromosome

• It contains X and Y chromosome
• It contains male characteristics

Female chromosome

• It contains a pair of X chromosome
• It contains female characteristics

(iii) During sexual reproduction, the genes from the parents (mother and father) interchange and develops a new individual. One chromosome from both of them takes part in the formation.

Females have only single pair of chromosome i.e X chromosome. While male have both X and Y chromosomes.

The child who inherits X chromosome from her father will be a girl, and one who inherits Y chromosome from him will be a boy. Thus, the sex of a child is determined by the father.