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 each trait separately

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

For the color trait (Y = yellow, y = green), the cross is \( Yy \times Yy \). The probability of getting \( yy \) (green) is \( \frac{1}{4} \) (genotypic ratio \( 1YY: 2Yy: 1yy \)).

Step2: Use the multiplication rule for independent events

Since the two traits (shape and color) are independent, we multiply the probabilities of each event. The probability of getting wrinkled (rr) and green (yy) is the product of their individual probabilities: \( \frac{1}{4} \times \frac{1}{4} = \frac{1}{16} \), which is a ratio of \( 1:16 \).

Answer:

A. 1:16