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Question 18M.2.HL.TZ2.3b

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Date May 2018 Marks available [Maximum mark: 3] Reference code 18M.2.HL.TZ2.3b
Level HL Paper 2 Time zone TZ2
Command term Determine Question number b Adapted from N/A
b.
[Maximum mark: 3]
18M.2.HL.TZ2.3b
(b)

The genes for cystic fibrosis and blood group are not linked. Two parents are heterozygous for cystic fibrosis. One parent has blood group O and the other has blood group AB. Using a Punnett square, determine the probability that their child will have both cystic fibrosis and blood group A.

[3]

Markscheme

a. correct parental genotypes shown / Ff ii, FfIA IB 

b. Punnett square with correct gametes shown 

c. correct probability:  1 8

                                   OR
                                   12.5%

Must use blood type symbols IB IA and i. No specific letters required to represent cystic fibrosis allele though dominant and recessive must be apparent.

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