Released STAAR Biology EOC · 2026 · Item 4 · 1 point

Walkthrough: Biology 2026, Item 4

B.8B · Genetic Crosses · unscored study

Roan cattle have red-and-white fur evenly distributed on the hide and have the genotype $RW$ . A roan cow is crossed with a red bull having the genotype $RR$ . What is the probability of the genotype $RW$ appearing in the offspring?

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1. Understand the question

This is a codominance cross: roan cattle ( $RW$ ) show both red and white. You need the probability of one genotype, $RW$ .

Try the question on your own first, then reveal one step at a time.

2. Solve it step by step

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