Edexcel IGCSE Biology · Spec 3.19-3.20
Genetics: Key Words
Key genetics terms you must know — gene, allele, dominant, recessive, genotype and phenotype.
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Genetics: Key Words
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Spec 3.19-3.20
What you need to know
- Understand what alleles are
- Use the words dominant and recessive
- Use genotype, phenotype, homozygous and heterozygous
Active recall
Quick check
Answer each question before opening the answer.
Define genotype and phenotype.
Genotype — the alleles an organism has; phenotype — the observable characteristics.
What is the difference between a dominant and a recessive allele?
A dominant allele is expressed with only one copy; a recessive allele is only expressed when two copies are present.
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