Question

Select all of the following genotypes that is/are homozygous?
zz
Aa
ZZ
Zz
AA
aa

Answer 1

Homozygous genotypes have two identical alleles for a particular gene. In your list, the following genotypes are homozygous:

- **zz** (homozygous recessive)
- **ZZ** (homozygous dominant)
- **AA** (homozygous dominant)
- **aa** (homozygous recessive)

The heterozygous genotypes in your list are:

- **Aa** (heterozygous)
- **Zz** (heterozygous)

So the homozygous genotypes are: **zz, ZZ, AA, aa.**