IGCSE Biology glossary
Homozygous
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Definition
Having two identical alleles of a particular gene.
What to include in an exam answer
the key terms are 'two identical alleles' of the same gene. Students drop the mark by writing 'two of the same gene' (it is alleles, not genes). Examiners also expect you to know that two homozygous parents of the same genotype always produce offspring with that genotype for that gene. Appears in Paper 4 genetic diagram questions.
Example in context
Describing a genotype: 'The plant TT is homozygous because it has two identical alleles of the gene for height.'
Related syllabus topic
Inheritance