How can a child have cystic fibrosis when neither of the parents have the disorder? (5 Marks)

• Cystic fibrosis is an autosomal recessive disorder, which is caused by a mutation in the CFTR (cystic fibrosis transmembrane conductance regulator) gene. • The defective CFTR protein does not allow Cl- ions to leave the cell, which leads to the build up of thick mucous in the lungs and pancreas.• To have the cystic fibrosis phenotype, you need to inherit 2 recessive alleles with this mutation from both parents. • If 2 recessive alleles are mutated, the child will be homozygous recessive. • If neither parent has the disease, they must be heterozygous for the cystic fibrosis allele.

Related Biology A Level answers

All answers ▸

Explain the sequence of events that occur in the control of the cardiac cycle.


Discuss how cholesterol is transported in the body, and describe these transport molecules.


Describe the process of the photosynthesis' light dependent reaction.


Explain the Bohr shift.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences