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: Find the probability of green seeds

For the \(Yy\times Yy\) cross (seed - color), the Punnett - square gives \(YY:Yy:yy = 1:2:1\). The probability of green seeds (\(yy\)) is \(\frac{1}{4}\).

Step2: Find the probability of wrinkled seeds

For the \(Rr\times Rr\) cross (seed - shape), the Punnett - square gives \(RR:Rr:rr=1:2:1\). The probability of wrinkled seeds (\(rr\)) is \(\frac{1}{4}\).

Step3: Use the multiplication rule

Since the two traits (seed - shape and seed - color) are independent (Mendel's law of independent assortment), we multiply the probabilities of each trait. \(P(\text{green and wrinkled})=P(\text{green})\times P(\text{wrinkled})\). So \(P=\frac{1}{4}\times\frac{1}{4}=\frac{1}{16}\), which is equivalent to a ratio of \(1:16\).

Answer:

A. \(1:16\)