Use a genetic diagram to work out the probability that the offspring have cystic fibrosis if both parents are carriers.

CF is a homozygous recessive condition. This means that it is inherited, ie a child gets the condition by the genetic material passed on to it from its parents. Let's call the faulty allele f (which is also the recessive allele) and let's call the non-faulty allele F (which is also the dominant allele). 
If both parents are carriers this means they have the genotype Ff. Being a carrier remember means that you still have one faulty allele but you do not present with symptoms as you do not have the disease because in order to be affected you must have 2 faulty alleles.
(In my lesson I would then draw out the genetic diagram to explain how the ratios can be calculated.)

EG
Answered by Eksha G. Biology tutor

3530 Views

See similar Biology GCSE tutors

Related Biology GCSE answers

All answers ▸

What is the difference between type 1 and type 2 diabetes?


What is the general structure of an animal cell?


Briefly describe how a vaccine works.


Describe the process of evolution by natural selection as developed by Charles Darwin in the 1800s.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning