Learning objective
Interpret crosses involving sex-linkage, autosomal linkage, multiple alleles and epistasis.
Read the explanation, check the common trap, then practise with flashcards and questions.
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Topic
Genetics and ecosystems official content
Subtopic
Inheritance
Study support
Understand this objective
Quick explanation
Interpret crosses involving sex-linkage, autosomal linkage, multiple alleles and epistasis
- This point belongs to Genetics and ecosystems official content, especially Inheritance.
- You need to be able to interpret crosses involving sex-linkage, autosomal linkage, multiple alleles and epistasis.
- The key ideas to know are allele and epistasis.
- Use the linked flashcards and practice questions to check recall, then practise applying the idea in an exam-style answer.
Key concepts
Why it matters
This objective helps connect Inheritance to exam-style questions, flashcards, and revision notes for Genetics and ecosystems official content.
Quick student answer
In a cross between two pea plants, one homozygous for tallness (T) and the other homozygous for shortness (t), what is the expected phenotypic ratio of the offspring?
Direct answer
The expected phenotypic ratio is 100% tall plants.
Key terms
- Multiple alleles: A situation where a gene has more than two alleles, leading to a variety of possible genotypes and phenotypes, such as in the ABO blood group system.
- Phenotypic ratio: The ratio of different phenotypes produced in the offspring from a genetic cross, reflecting the expression of alleles.
Common trap
Confusing dominant and recessive alleles: Remember that dominance refers to the expression of the phenotype, not its frequency in the population.
Related questions
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Revision notestopic notes
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Open revision notesRelated learning objectives
- Define genotype and phenotype.
Inheritance
- Use dominant, recessive, codominant, homozygous and heterozygous terminology.
Inheritance
- Use fully labelled genetic diagrams for monohybrid and dihybrid crosses.
Inheritance
- Use chi-squared testing to compare observed and expected phenotypic ratios.
Inheritance
- Define a population as organisms of the same species in a space and time that can potentially interbreed.
Populations