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 \( Tt \times tt \): Using Punnett square, the offspring genotypes would be \( Tt \) and \( tt \) (50% each), so not 100% heterozygous.
• For option \( Tt \times Tt \): Offspring genotypes are \( TT \), \( Tt \), \( tt \) in ratio 1:2:1, so not 100% heterozygous.
• For option \( tt \times tt \): All offspring are \( tt \) (homozygous), not heterozygous.
• For option \( TT \times tt \): Using Punnett square, all offspring will have genotype \( Tt \) (since \( TT \) gives \( T \) and \( tt \) gives \( t \), so each offspring gets \( T \) from one parent and \( t \) from the other), which is heterozygous.

Answer:

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