DP Biology (first assessment 2025)

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Question 22N.1A.HL.TZ0.35

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Date November 2022 Marks available [Maximum mark: 1] Reference code 22N.1A.HL.TZ0.35
Level HL Paper 1A Time zone TZ0
Command term Question number 35 Adapted from N/A
35.
[Maximum mark: 1]
22N.1A.HL.TZ0.35

Black, short-haired guinea pigs, heterozygous for both characteristics, were crossed. They produced offspring with the phenotypes black short-haired, black long-haired, white short-haired and white long-haired in the ratio 9:3:3:1. A different cross produced offspring with phenotypes in the ratio 1:1:1:1. What were the genotypes of the parents in the second cross?

A.  BbSs × BbSs

B.  BBSs × BbSS

C.  BbSs × bbss

D.  bbSS × BBss

[1]

Markscheme

C

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