We read your photo as:

The problem states that both parents have sickle cell trait. This means they are heterozygous for the gene.

Biology

ScanSolve AI Answer

Answer

a

14\frac{1}{4}

Step-by-step solution

4 steps

Here is the working for the sickle cell anaemia question:

Part a· 4 steps

Proportion of offspring with sickle cell anaemia

  1. Identify the genotypes of the parents.

    The problem states that both parents have sickle cell trait. This means they are heterozygous for the gene.
    Let H represent the gene for normal haemoglobin and S represent the gene for abnormal haemoglobin.
    Parent 1 genotype: HS
    Parent 2 genotype: HS

  2. Construct a Punnett square to determine the possible genotypes of the offspring.

    GametesHSHHHHSSHSSS\begin{array}{|c|c|c|} \hline \text{Gametes} & \text{H} & \text{S} \\ \hline \text{H} & \text{HH} & \text{HS} \\ \hline \text{S} & \text{HS} & \text{SS} \\ \hline \end{array}

  3. Determine which genotype results in sickle cell anaemia.

    Sickle cell anaemia occurs in individuals who are homozygous for the abnormal haemoglobin gene, which is the SS genotype.

  4. Calculate the proportion of offspring with sickle cell anaemia.

    From the Punnett square, there are 4 possible outcomes for the offspring's genotypes: HH, HS, HS, SS.
    One out of these four outcomes is SS.
    Therefore, the proportion of offspring with sickle cell anaemia is 14\frac{1}{4}.

    The proportion of their offspring that have sickle cell anaemia is 14\boxed{\frac{1}{4}}.

Part b

Explanation for prevalence of sickle cell trait in tropical countries

Sickle cell trait (HS genotype) is more prevalent in tropical countries because it offers a survival advantage against malaria. These regions often have a high incidence of malaria, a parasitic disease. Individuals with the sickle cell trait are resistant to malaria because the presence of some abnormal haemoglobin makes their red blood cells less hospitable for the malaria parasite. This resistance increases their chances of survival and reproduction in malaria-prone areas, leading to a higher frequency of the sickle cell allele in the population through natural selection.

Was this helpful?

Try one yourself

A new problem that tests the same skill.

Still stuck on this one?

Ask a follow-up, and the answer starts from this question.

Got a different question?Ask your own question

More Biology Questions

QA couple, both with sickle cell trait (heterozygous), are planning to have children. What is the…QIf both parents have sickle cell trait, work out the proportion of their offspring that have sickle…QQuestion 2.c. requires determining the genotypes of parents based on phenotypic information…QThe problem states that normal haemoglobin is Hb^A and abnormal haemoglobin (sickle-cell) is Hb^S…QA) Determine the probability that their first born will have the sickle cell trait.
Browse by topic:Genetics
See all Biology questions →
Got a syllabus? Photograph it and I'll tell you what's due and what's worth the most.
Handwritten step-by-step solution preview

Handwritten Step-by-Step Solution

Get this as a handwritten image on WhatsApp — like a tutor wrote it for you.

Try on WhatsApp