Biology A-Level
epistasis
What epistasis means in Biology A-Level, as defined for AQA, OCR.
Definitions of epistasis
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Reference: OCR
Occurs when one gene masks or modifies another, signalled by a 9:3:4, 12:3:1 or 9:7 ratio rather than independent assortment.
When one gene masks another, altering the 9:3:3:1 ratio, for example to 9:3:4.
Topics that use epistasis
- Inheritance (A-level only) (AQA A-Level)
- Patterns of inheritance (OCR A-Level)
Related terms
- critical value
- degrees of freedom
- null hypothesis
- Phenotype
- sex linkage
- allele
- Allele frequencies
- Alleles, genotypes and phenotypes
Using epistasis in the exam
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