Alleles found at the same locus.on homologous chromosomes,

Homozygotes (pure breds)

Heterozgote (hybrid)

Dominant Allele is expressed in a homozygote and heterozygote

Recessive Allele is only expressed in a homozygote.

Phenotype (appearance)

Genotype (combination of alleles)

Monohybrid Cross -one characteristic is used

Dihybrid Cross - two characteristics are used

Segregation and Independent Assortment of Alleles when the alleles
are on separate chromosomes.