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Sickle cell anaemia is a hereditary disease due to a recessive gene which changes normal haemoglobin (Hb – A) to abnormal haemoglobin (Hb – S). The...

Sickle cell anaemia is a hereditary disease due to a recessive gene which changes normal haemoglobin (Hb – A) to abnormal
haemoglobin (Hb – S). The red blood cells of people with sickle cell anaemia are sickle shaped.
(a) What are the possible phenotypes of the offsprings of a man who is heterozygous and a woman who is also heterozygous?
Show your working.
(b) Sickle cell trait is more prevalent in tropical countries than in temperate countries. Give an explanation for this observation.

Answers

sharon
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b) In tropical countries malaria incidence is high ; those who are heterozygous have immunity to malaria; this is called heterozygous advantage. or
In tropical countries malaria incidences is high; those who are heterozygote have some red blood cells with crescent shape thus low oxygen carrying capacity plasmodium content therefore survive in such conditions making them to have an immunity ;
sharon kalunda answered the question on March 21, 2019 at 14:02

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