CAPE Biology Unit 1 · 2012 · Paper 1 · Question Q23

When a cross was made between a purebreeding pea plant with green, round seeds and a pure breeding plant with yellow, wrinkled seeds, all of the \text{F}_1 progeny had yellow round seeds. Which of the following ratios shows the result of a test cross of the \text{F}_1 generation?

1. (A)Yellow Round: 1, Yellow Wrinkled: 1, Green Round: 1, Green Wrinkled: 1
2. (B)Yellow Round: 3, Yellow Wrinkled: 1, Green Round: 3, Green Wrinkled: 1
3. (C)Yellow Round: 3, Yellow Wrinkled: 3, Green Round: 1, Green Wrinkled: 1
4. (D)Yellow Round: 9, Yellow Wrinkled: 3, Green Round: 3, Green Wrinkled: 1

This question uses a figure or table from the paper — you'll see it when you practise.