Question

two true - breeding stocks of pea plants are crossed. one parent has red axial flowers, and the other has white terminal flowers; all f1 individuals have red axial flowers. the genes for flower color and location assort independently. if 1,000 f2 offspring resulted from the cross, approximately how many of them would you expect to have red terminal flowers? 65 190 250 565

Explanation:

Step1: Determine dominant and recessive traits

Since all F1 individuals have red axial flowers, red (R) is dominant over white (r) for flower color, and axial (A) is dominant over terminal (a) for flower location. The parental cross is \( RRAA\times rraa \), and F1 is \( RrAa \).

Step2: Analyze F2 generation using Punnett square or probability rules

For two - gene cross \( RrAa\times RrAa \), the probability of getting red terminal flowers (\( R\_aa \)):
The probability of \( R\_ \) (either \( RR \) or \( Rr \)) is \( \frac{3}{4} \) (from \( RR:Rr:rr = 1:2:1 \) for a single - gene cross \( Rr\times Rr \)), and the probability of \( aa \) (from \( Aa\times Aa \) with \( AA:Aa:aa=1:2:1 \)) is \( \frac{1}{4} \).
Using the multiplication rule for independent events, the probability of \( R\_aa \) is \( \frac{3}{4}\times\frac{1}{4}=\frac{3}{16} \).

Step3: Calculate the number of F2 individuals with red terminal flowers

If there are \( N = 1000 \) F2 offspring, the number of individuals with red terminal flowers is \( n=\frac{3}{16}\times1000\approx190 \)

Answer:

190