Will be produced. [5]
5
S7 The diagram shows a pedigree chart for a family in which some of the members are red-green
colour-blind,
1
2
HIGHEST QUALITY GRAPHITE LI
8
9
10
3
4
6
7
5
16
17
18
19
12
15
20
13
14
normal male
colour-blind female
colour-blind male
()
normal female
0610142 je mali
QB C
a
b
Explain how the pedigree supports the idea that red-green colour blindness is a
urte [2]
Using the symbols XB for the allele for normal vision, and Xb for the allele for colour blindness, arru
state the genotypes of each of the following individuals. If there is more than one possible
genotype, write down both of them.
2, 3, 11, 13, 19
15
If individuals 3 and 4 have another son, what is the probability that he will be colour-blind?
Use a genetic diagram to explain your answer.
(5)
Explain why a colour-blind man cannot pass on this condition to his son.
[2]
с
d​