Question $3$

$0\mathrm{.}4$ points

The beta$-$islet cell related gene $($BICR$)$ is on the X$-$chromosome. Males with a recessive mutation in BICR fail to regulate blood sugar$-$levels. What happens in heterozygous females with this mutation.

A$.$ Approximately have the beta$-$islet cells will be defective, but the other half will be functional.

B$.$ Estrogen, a female hormone, will be unable to regulate beta$-$islet cells which express this mutation, since $x-$chromosome genes are involved in sex$-$dependent functions.

C$.$ These females do not display this phenotype, since they are heterozygous and the mutation is recessive, the wild$-$type copy of the gene compensates.

D$.$ Heterozygous females don't display a phenotype, thus the wild$-$type copy of this gene must escape silencing

E$.$ The X$-$chromosome in which this mutation is on is inactivated, thus heterozygous females do not display the phenotype, like the X$-$linked colorblindness phenotype.