Exercise 3: Genetic Inheritance Problems (11 marks)
4. Some people suffer from a form of colour-blindness in the red/green spectrum. This
type of colour-blindness is linked to a recessive allele on the female sex
chromosome (X chromosome) - this is referred to as an X-linked disorder. Inez,
who has normal colour vision, has recently inherited her family's tomato farm. Inez is
planning to marry Samuel, a male with colour-blindness. Inez's biological father was
colour-blind, which made it difficult for him to work on the family tomato farm. Also in
the picture is Roberto, who is not colour blind and would like to persuade Inez to
marry him instead of Samuel. For this problem use $X^N$ for normal vision and $X^c$ for
colour-blindness. (5 marks)
a. What is the genotype of Inez's father? (0.5)
b. Inez is not colour blind, what is her genotype? (0.5)
c. What is Samuel's genotype?
How do you know? (1)
d. What is Roberto's genotype? (0.5)
e. If Inez marries Samuel, what percentage of their offspring will be good tomato
pickers? (Use the Punnett square). (1).
f. If Inez marries Roberto, what percentage of their offspring would be good tomato
pickers? (Use the Punnett square). (1).