Using “T” to represent a dominant allele (version) of a gene and “t” for the recessive allele:

Question

Which of the below combinations is homozygous dominant? ______
Which of the below combinations is homozygous recessive? ______
Which of the below combinations is heterozygous? ______

T T T t t t

Answer 1

The combination T T is homozygous dominant.
The combination t t is homozygous recessive.
The combination T t is heterozygous.