In humans, cystic fibrosis is a recessive genetic disorder that results in mucus clogging major organs. if both parents are genetically heterozygous for cystic fibrosis, then what are their chances of having a child with the disease?

The right answer is 25%.

Here are the different cross between the gametes of parents:

A: healthy allele

a: sick allele.

Aa   x     Aa

AA, Aa, Aa, aa

Since cystic fibrosis is an autosomal recessive disease (chromosome 7): The disease is expressed only in children with two sick alleles (aa) (which represents one in four children). Those with only one sick allele (Aa) will carry the disease.

supercell thunderstorms are perhaps the most violent of all thunderstorm types, and are capable of producing damaging winds, large hail, and weak-to-violent tornadoes