Question

2. If a heterozygous fire-breathing dragon is crossed with one that does not breathe fire, what is the probability that the first born will be a fire breather? (2)

Answer 1

Answer: 50% (1/2) probability is there that the first born will be a fire breather.

Explanation: In heterozygous condition the character of breathing fire is expressed that means it is a dominant character. (Dominant characters are expressed in homozygous as well as heterozygous condition while a recessive character is expressed only in homozygous recessive condition)

Let the allele for the character of breathing fire be expressed as ‘F’

Hence the allele for the character of not able to breathe fire will be ‘f’

Therefore the genotype of the heterozygous fire breathing dragon will be ‘Ff’

Gamates produced will be of two types ‘F’ and ‘f’

And the genotype of dragon who does not breathe fire will be ‘ff’

The gamates produced will be of one type ‘f’

If the above two dragons mate, then the possible genotypes and phenotypes of the offspring can shown by the Punnett square as follows:

gamates	F	f
f	Ff fire breather	ff Cannot breathe fire
f	Ff fire breather	ff Cannot breathe fire

Hence there is 50% chance of the offspring born will be a fire breather