Question

shows family Pedigree to show the inheritance of sciatic fibrosis​

Answer 1

Answer:

Question a) Diagram as below

Question b) No. (explanation below)

Explanation:

r - [recessive allele] HAS the disease (cystic fibrosis)

R - [dominant allele] normal (does NOT have cystic fibrosis)

Question a)

We know:

- Daddy: normal alleles > RR

- Mummy: carrier > Rr

You would initially think that Mummy has normal alleles [RR} like Daddy because she does not have cystic fibrosis, however, Mummy is a carrier for the disease, due to this, her alleles would be Rr. As to be presenting the disease you would need to have two recessive alleles of rr. However, as she is only a carrier she would have a dominant allele. They actually gave you this as a hint in the diagram whether the first filled in square reads "Rr"

Therefore, the diagram would read:

          R          R

r         Rr         Rr

R        RR        RR

Question b)

Based off the information presented in the diagram:

- 50% of offspring would be Rr

           [does NOT have disease but are carriers of cystic fibrosis]

- 50% of offspring would be RR

           [does NOT have disease]

Therefore, 0% of offspring will have cystic fibrosis based on this genetic cross.