Answer the following briefly:
(i) Explain with the help of a chart what will be the colour of a child's hair if father has got dominant gene for black hair and mother has recessive gene for brown hair?
(ii) Explain the following terms:
(a) Laws of Inheritance.
(b) Identical twins.
(iii) Family consists of two parents and their five children and the pedigree chart below shows the inheritance of the trait colour blindness.

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Solution

(i) If the father has a dominant gene for black hair, BB, and the mother has a recessive gene for brown hair, bb, then the colour of the child's hair will be black.

Gametes b b

B Bb
Black Bb
Black

B Bb
Black Bb
Black

(ii) (a) The Laws of Inheritance were proposed by Gregor Mendel. The following are the three Laws of Inheritance.

Law of Dominance: According to this law, characters are controlled by discrete units called factors, which occur in pairs, with one member of the pair dominating the other in a dissimilar pair.

Law of Segregation: This law states that the two alleles of a pair segregate or separate during gamete formation in such a way that a gamete receives only one of the two factors.

Law of Independent Assortment: This law states that when two pairs of traits are combined in a hybrid, one pair of characters segregates independent of the other pair of characters.
(b) Identical twins are twins with exactly the same genetic make-up.

(iii) The process of transfer of traits from parents to offspring is called heredity.

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Figure

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