Q2 of 32 Page 32

Two pairs (A & B) of rabbits were crossed as given below:


(a) Can you tell which coat' colour (black or white) is dominant? ………………………….


(b) Is the coat colour sex-linked? …………….

(a) According to Mendel’s law of dominance, out of a pair of contrasting characters present together, only one is able to express itself while the other remains suppressed. The expressed character is “dominant” while the unexpressed character is the “recessive”.

Thus, in the given pairs, black is dominant charter while white is a recessive character.


(b) Coat colour is not a sex-linked inheritance. Hemophilia and colour blindness are examples of sex-linked inheritance.


More from this chapter

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3

Does the sex of the child depend on the father or it is just a matter of chance? Discuss.

 1

In a certain species of animals, black fur (B) is dominant over brown fur (b). Predict the genotype and phenotype of the offspring when both parents are 'Bb' or have heterozygous black fur.

 3

Make a Punnett square for finding out the proportion of different genotypes in the progeny of a genetic cross between

(a) A pure tall (TT) pea plant with a pure dwarf (tt) pea plant.


(b) Red flower variety of pea (RR) with white flower variety of pea (rr).

 4

A family consists of two parents and their five children and the pedigree chart below shows the inheritance of the trait colour blindness in them.


(a) Who is colour blind in the parents - the Father or the Mother?


(b) How many daughters and how many sons have been born in the family?


(c) What does the child 1 indicate about this trait?


(d) On which chromosome is the gene of this trait located?


(e) Name one other trait in humans which follows the similar pattern of inheritance.