Correct Option: A. 25% wrinkled, 75% round Explanation of the Correct Answer In this breeding program, we are dealing with two true-breeding types of cow-peas: one with round seeds (dominant trait) and one with wrinkled seeds (recessive trait). To understand the outcome of the first filial generation (F1), we can use a simple genetic approach based on Mendelian inheritance.

1. Identify the Genotypes:
2. The round seed trait is dominant, which we can denote as "R".
3. The wrinkled seed trait is recessive, denoted as "r".
4. The true-breeding round seeds will have the genotype "RR" (homozygous dominant).
5. The true-breeding wrinkled seeds will have the genotype "rr" (homozygous recessive).
6. Perform the Cross:
7. When we cross these two true-breeding plants, we are essentially performing a monohybrid cross:
   • Parent 1 (Round seeds): RR
   • Parent 2 (Wrinkled seeds): rr
8. The gametes produced by each parent will be:
   • Parent 1 can only produce gametes with the "R" allele (since it is homozygous).
   • Parent 2 can only produce gametes with the "r" allele (also homozygous).
9. F1 Generation:
10. When we combine the gametes from both parents, all offspring in the F1 generation will have the genotype "Rr":
    • R (from the round parent) + r (from the wrinkled parent) = Rr
11. Since "R" is dominant over "r", all the seeds produced in the F1 generation will exhibit the round seed phenotype.
12. Phenotypic Ratio:
13. In this case, since all offspring are "Rr", they will all display the round seed phenotype. Therefore, the phenotypic ratio in the F1 generation is:
    • 100% round seeds.

Explanation of Why Other Options Are Incorrect

• Option B: 100% wrinkled:
• This option is incorrect because the wrinkled trait is recessive. Since all offspring are "Rr", they will not express the wrinkled phenotype at all.
• Option C: 50% wrinkled, 50% round:
• This option is incorrect because it suggests a mix of phenotypes that would occur if we had a different cross, such as Rr x Rr. In this case, since we are crossing true-breeding parents (RR x rr), all offspring are "Rr" and thus 100% round.
• Option D: 75% wrinkled, 25% round:
• This option is also incorrect. It implies a typical Mendelian ratio that would occur in a dihybrid cross or a cross between heterozygous individuals (Rr x Rr). However, since we are crossing a homozygous dominant with a homozygous recessive, all offspring are round.

Summary of Key Points

• The round seed trait (R) is dominant, while the wrinkled seed trait (r) is recessive.
• A cross between true-breeding round (RR) and true-breeding wrinkled (rr) results in all offspring being heterozygous (Rr).
• All F1 generation seeds will display the dominant round phenotype (100% round).
• Understanding the principles of Mendelian genetics is crucial for predicting offspring traits in breeding programs.