Question

Two organisms that are true-breeding for a certain genetic characteristic are mated and their offspring were analysed. Which of the following statements about this situation is correct?

• A. Both parents are homozygotes.
• B. The offspring are either all homozygotes or all heterozygotes.
• C. The offspring represent the $F_1$ generation and the gametes produced by the offspring will carry only one allele for this gene.
• D. All of the above

Answer 1

Answer: (D)

Given that both parents are true-breeding, the cross must be either $AA \times AA, AA \times aa$, or $aa \times aa$. If you work out these crosses, you will see that all of the possible answers are true for each possible situation.