Question

Drosophila eye color is an X-linked trait. Red eye color is dominant, and white eye color is recessive. Which Punnett square shows a cross in which the probability that offspring will be red-eyed males is 25 percent?

A Punnett square is shown. The columns are labeled Upper X r and Upper Y. The rows are labeled x Upper R and x Upper R. Clockwise, from top-left, the boxes include: X Upper R X r, X Upper R Y, X Upper R Y, X Upper R X r.

A Punnett square is shown. The columns are labeled Upper X r and Upper Y. The rows are labeled x Upper R and x r. Clockwise, from top-left, the boxes include: Upper X r Upper X r, Upper X r Upper Y, Upper X r Upper Y, Upper X r Upper X r.

A Punnett square is shown. The columns are labeled Upper X r and Upper Y. The rows are labeled x r and x r. Clockwise, from top-left, the boxes include: Upper X r Upper X r, Upper X r Upper Y, X r Upper Y, Upper X r Upper X r.

A Punnett square is shown. The columns are labeled Upper X Upper R and UpperY. The rows are labeled x r and x r. Clockwise, from top-left, the boxes include: Upper X r Upper X Upper R, Upper X r Upper Y, X r Upper X Upper R, Upper X r Upper X Upper R.
Mark this and return

Answer 1

The second Punnett square. It represents X^R X^r (female) × X^r Y (male), which gives X^R Y (red male) in 1 of 4 boxes = 25%.