Question

homework - non-mendelian genetics
a brood of chicks (from the previous example) recently hatched, and they are all from the same two parents. the phenotype ratio of the chicks is 2 black: 2 speckled (reduced to 1 black: 1 speckled). the genotypes of their parents were most likely
bw × bw
bb × ww
bw × ww
bb × bw

Explanation:

Step1: Analyze \( BW\times BW \)

$$\begin{array}{|c|c|c|} \hline & B & W \\ \hline B & BB & BW \\ \hline W & BW & WW \\ \hline \end{array}$$

Phenotype ratio: \( 1\) black (\(BB\)) : \( 2\) speckled (\(BW\)) : \(1\) white (\(WW\))

Step2: Analyze \( BB\times WW \)

$$\begin{array}{|c|c|c|} \hline & B & B \\ \hline W & BW & BW \\ \hline W & BW & BW \\ \hline \end{array}$$

All offspring are \( BW \) (speckled)

Step3: Analyze \( BW\times WW \)

$$\begin{array}{|c|c|c|} \hline & B & W \\ \hline W & BW & WW \\ \hline W & BW & WW \\ \hline \end{array}$$

Phenotype ratio: \( 1\) speckled (\(BW\)) : \(1\) white (\(WW\))

Step4: Analyze \( BB\times BW \)

$$\begin{array}{|c|c|c|} \hline & B & B \\ \hline B & BB & BB \\ \hline W & BW & BW \\ \hline \end{array}$$

Phenotype ratio: \( 1\) black (\(BB\)) : \(1\) speckled (\(BW\))

Answer:

\( BB\times BW \)