Photo AI
Sickle cell disease is caused by a change in one of the bases coding for an amino acid on chromosome 11 - Edexcel - GCSE Biology - Question 4 - 2016 - Paper 1
Question 4
Sickle cell disease is caused by a change in one of the bases coding for an amino acid on chromosome 11. (a) Complete the sentence by putting a cross (✗) in the box... show full transcript
Worked Solution & Example Answer:Sickle cell disease is caused by a change in one of the bases coding for an amino acid on chromosome 11 - Edexcel - GCSE Biology - Question 4 - 2016 - Paper 1
Step 1
Step 2
Complete the genetic diagram to show the possible genotypes from two heterozygous parents.
Answer
The completed genetic diagram shows the following combinations:
- FF: Homozygous healthy (normal)
- Ff: Heterozygous carrier
- ff: Homozygous sickle cell
From two heterozygous parents (Ff x Ff), the offspring can be FF, Ff, or ff.
Step 3
Calculate the percentage probability that the offspring will be carriers of the sickle cell allele but not have sickle cell disease.
Answer
To calculate the probability:
- The genotypes are FF (25%), Ff (50%), and ff (25%).
- The probability of being carriers (Ff) is 50%.
Thus, the percentage probability that the offspring will be carriers of the sickle cell allele but not have sickle cell disease is 50%.