please answer all parts

4. In humans, cystic fibrosis is caused by a defect in a single gene where the recessive allele (n) makes a non-functional transport protein. When individuals have two recessive alleles they have the disease. Two parents that do not have the disease have a child with cystic fibrosis. a What are the genetynes of the parents? bi What is the chance that the child's sister will shinelystfibrose