1. Heterozygous vs Homozygous

2. Heterozygous vs Homozygous
Pairs of alleles can be either heterozygous or Homozygous.
An allele are a pair of genes (section of DNA).

3. Heterozygous
Heterozygous means that there are two different alleles, one being dominate and the other is recessive.
This is represented by letters
For example: Rr, Gg, Tt
The capital means dominate gene, while the lower case means recessive.

4. Homozygous Means that both alleles are exactly the same.
For example: FF, GG, TT

5. Dominate and recessive
A dominate allele will always be expressed over a recessive allele.
For Example:
Brown eyes are dominant to blue eyes, thus brown eyes are given the letter B, as blue eyes are given the letter b. If a person has the alleles Bb, they will have brown eyes, BB they will have brown eyes, bb they will have blue eyes.