Question

1. liana has sickle cell disease. given that information, which statement is correct?

one of her parents must have sickle cell disease also.
the airways in lianas lungs get blocked with thick mucus.
both her parents must be carriers of the sickle cell gene.
lianas blood does not clot normally when she gets a cut.

Explanation:

Sickle cell disease is an autosomal recessive disorder. For an individual to have the disease (homozygous recessive, say \( ss \)), each parent must contribute a recessive allele (\( s \)). So, both parents must be carriers (\( Ss \)).

• Option 1: Parents could be carriers (\( Ss \)) without having the disease (\( ss \)).
• Option 2: Blocked airways with thick mucus is a symptom of cystic fibrosis, not sickle - cell disease.
• Option 4: Abnormal blood clotting is a symptom of hemophilia, not sickle - cell disease.

Answer:

Both her parents must be carriers of the sickle cell gene.