Question

dominance in genetics is on a spectrum. how many recessive alleles for sickle cell disease does a person have to have to still express aspects of the trait? 2 1 23 46

Explanation:

Sickle cell disease is an autosomal recessive disorder, but it also shows incomplete dominance. In the case of expressing aspects of the sickle - cell trait (like having some sickle - shaped cells), having 1 recessive allele (in the context of the heterozygous condition, where the genotype is $Hb^A Hb^S$) is sufficient to express aspects of the trait. Having 2 recessive alleles ($Hb^S Hb^S$) leads to full - blown sickle cell disease. The number 23 is related to the number of chromosome pairs in humans (not related to the number of alleles for this trait), and 46 is the total number of chromosomes in a human somatic cell (also not related to the allele count for this trait).

Answer:

1 (the option with "1")