Family Trees

• Is cystic fibrosis a dominant or recessive condition?

  Recessive 
• Cystic fibrosis is a recessive condition. Which of the genotypes below would result in an individual having cystic fibrosis?

  
  

  Homozygous recessive

  
  

  As cystic fibrosis is a recessive condition, a person would have to have two copies of the cystic fibrosis allele to have the condition. 
• Cystic fibrosis is a recessive condition.

  Which of the genotypes would result in an individual being a carrier for cystic fibrosis?

  Heterozygous 

  A carrier is somebody who only carries one copy of a recessive allele, and so doesn't suffer from the condition itself. 
• FF

  Harry is represented by a light shaded square. From the key we can see that the square shows that he's male, while the light shade shows that he doesn't have the disease. 

  
• no

  Cystic fibrosis is a recessive condition, so for a child to have the condition they would need to inherit it from both parents. Ryan doesn't carry a cystic fibrosis allele though, so his children couldn't inherit one from him.