Question

in a dihybrid cross for round and yellow seeds (rryy x rryy), what is the probability of having green and wrinkled seeds?
key: r = round
r = wrinkled
y = yellow
y = green
○ 1:16
○ 3:16
○ 8:16
○ 9:16

Explanation:

Step1: Analyze seed shape (R/r)

For the shape (round - R, wrinkled - r), the cross is \( Rr \times Rr \). Using the Punnett square, the probability of \( rr \) (wrinkled) is \( \frac{1}{4} \) (since \( Rr \times Rr \) gives \( RR:Rr:rr = 1:2:1 \), so \( rr \) is \( \frac{1}{4} \)).

Step2: Analyze seed color (Y/y)

For the color (yellow - Y, green - y), the cross is \( Yy \times Yy \). The probability of \( yy \) (green) is \( \frac{1}{4} \) (from \( Yy \times Yy \) giving \( YY:Yy:yy = 1:2:1 \), so \( yy \) is \( \frac{1}{4} \)).

Step3: Combine probabilities

For dihybrid cross, we multiply the probabilities of each trait. So probability of green (yy) and wrinkled (rr) is \( \frac{1}{4} \times \frac{1}{4}=\frac{1}{16} \), which is \( 1:16 \).

Answer:

1:16