Secondary IV • 1mo.
Hello,
How would I solve this question?
In tomatoes, the allele for purple stems (P) is dominant over the allele for green stems (p). Second, the allele for red fruit (R) is dominant over the allele for yellow fruit (r). Using the following family tree, predict the probability that of the third generation offspring having a green stem (p) and red fruit (R).
Family tree:
- pprr + PPRr
- Pp?? + ppRr
- ?
I know how to draw Punnett squares, I'm just not sure how to use them when given several generations.
Explanation from Alloprof
This Explanation was submitted by a member of the Alloprof team.
Hi
thank you for your question!
To solve this type of problem, you start by making a Punnett square for the first generation, in this case: pprr × PPRr. This allows you to determine the possible genotypes of their offspring, which make up generation 2.
Next, you take the genotypes from generation 2 and cross them with the other parent, which is ppRr, to see the possible combinations for generation 3.
For each combination, you look at the probability of getting pp (green stem) and R (red fruit). To find the answer, you need to multiply the probabilities from the second-generation crosses with those from the third generation, which lead you to the desired phenotype.
Feel free to ask if you have any other questions!