Question

the offspring of a particular cross are 100 percent heterozygous for the trait of plant height. what were the most likely genotypes of the parents?
○ tt × tt
○ tt × tt
○ tt × tt
○ tt × tt

Explanation:

Step1: Analyze each option

• For option Tt × tt: Using Punnett square, the offspring genotypes would be Tt and tt, so not 100% heterozygous.
• For option Tt × Tt: Offspring genotypes are TT, Tt, Tt, tt, so not 100% heterozygous.
• For option tt × tt: All offspring are tt (homozygous), not heterozygous.
• For option TT × tt: Using Punnett square, all offspring will have genotype Tt (heterozygous), since TT can only contribute T and tt can only contribute t.

Step2: Conclusion

Only the cross between TT and tt results in 100% heterozygous offspring (Tt).

Answer:

D. TT × tt (assuming the options are labeled A: Tt × tt, B: Tt × Tt, C: tt × tt, D: TT × tt)