What other word from this unit has a prefix homo and means to have two copies of the same allele

The correct answer is homozygous.

Homozygous is a term for genotype that has identical alleles for a single trait.  

An allele is a form of a gene and diploid organisms have two alleles for a given trait: one inherited from father and one for mother.

Homozygous alleles may be dominant or recessive. A homozygous dominant has two dominant alleles and expresses the dominant phenotype (expressed physical trait), while homozygous recessive has two recessive alleles and expresses the recessive phenotype.

the wires in the toaster turning red and the toast crisping and turning brown