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Question 18M.2.SL.TZ1.a

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Date May 2018 Marks available [Maximum mark: 3] Reference code 18M.2.SL.TZ1.a
Level SL Paper 2 Time zone TZ1
Command term Explain Question number a Adapted from N/A
a.
[Maximum mark: 3]
18M.2.SL.TZ1.a

Using the Punnett grid, explain how two parents can have children with any of the different ABO blood groups.

[3]

Markscheme

a. correct gametes of one parent as IA AND i in header line/column
AND
correct gametes of other parent as IB AND i in header column/line 

b. correct corresponding genotypes in inner squares as IAIB, IAi, IBi, ii 

c. corresponding phenotypes of children identified as AB, A, B and O 

d. ratio of phenotypes is 1:1:1:1  OWTTE

Allow ECF.

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