Nancy and cliff had four children who did not have cystic fibrosis, but their fifth child was born with the disease. cystic fibrosis is carried on a recessive gene. given what you've learned in this chapter, how could this happen?
a. their fifth child must have been a girl, which makes it more probable that she would have the illness
b. their fifth child must have been a boy, which makes it more probable that he would have the illness
c. it wasn't until the fifth child that both parents passed on the allele for this illness. it wasn't until the fifth child that both parents passed on the allele for this illness.
d. recessive genes normally skip a generation, but after the parents had five children, the gene was expressed

It wasn't until the fifth child that both parents passed on the allele for this illness.

Explanation:

The most likely hypothesis is that both parents are heterozygous, carrying the gene for cystic fibrosis (Aa), but not manifesting it, because it is a disease caused by a recessive allele (a), so only recessive homozygous individuals (aa) can have the disease.

AA = Homozygous dominant - Does not manifest cystic fibrosis;

Aa = Heterozygous - Carrier of the trait for cystic fibrosis but do not manifest the disease;

aa = Recessive homozygous - Manifest cystic fibrosis.

Being the parents heterozygous, children with the following allele genes can be generated according to their percentages:

Parent alleles: Aa x Aa

Possible alleles of children:

A x A = AA = 25%

A x a = Aa = 25%

a x A = Aa = 25%

a x a = aa = 25%

According to the scheme above, it is possible to state that in this case there is a 25% chance of a recessive homozygous (aa) child being born, which explains the fact that only the fifth child was born with cystic fibrosis, while the others may not have the trait (AA) or may just be carriers of the gene (Aa), which also do not manifest cystic fibrosis.

slitherio is the original. its the best friend of all middle schoolers. the man you can count any time you have some free time. slitherio is the guy you hang with while you're in the computer lab suppose to be doing "research or whatever". slitherio isn't just a game but a friend.

wormaxio is just a fake trying to squeeze its way into the friend group. trying to pretend its cool and your best pal but how long has it really been there for you, really. it only wants you as friend to boost its social status. wormaxio is just annoying fake pleb. no offense

you and have a wonderful day

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation: