This deep dive covers Two Inherited Disorders for AQA within Inherited Disorders for GCSE Biology. Genetic disorders, family pedigrees, and probability calculations It is section 1 of 11 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.
Two Inherited Disorders for AQA
CYSTIC FIBROSIS (Recessive)
Caused by: Recessive allele (ff) — both parents must be carriers
Effects:
- Thick, sticky mucus in lungs and digestive system
- Difficulty breathing, frequent infections
- Digestive problems (enzymes can't reach food)
Inheritance: If both parents are carriers (Ff), 25% chance of affected child
POLYDACTYLY (Dominant)
Caused by: Dominant allele (P) — only one copy needed
Effects:
- Extra fingers or toes
- Can be surgically corrected
- Not usually harmful
Inheritance: If one parent has Pp, 50% chance of affected child
Practice questions for Inherited Disorders
What is an inherited disorder?
Describe how genetic screening can be used to detect inherited disorders.
Quick recall flashcards
What is polydactyly and how is it inherited?
Polydactyly is a dominant disorder — having just ONE copy of the dominant allele (Pp or PP) causes extra fingers or toes. Only one affected parent is needed to pass it on. It is usually not harmful and can be corrected surgically.
What is cystic fibrosis and how is it inherited?
Cystic fibrosis is a recessive disorder caused by having two copies of the faulty allele (ff). It causes thick, sticky mucus to build up in the lungs and digestive system, leading to breathing difficulties and frequent infections.