Final answer:
Cystic fibrosis (CF) is a genetic disease that affects the lungs, pancreas, liver, and intestines. It occurs when both parents are carriers of the defective gene.
Step-by-step explanation:
Cystic fibrosis (CF) is the condition that affects the lungs, pancreas, liver, and intestines when the defective gene is present in a child whose both parents are carriers of this autosomal recessive genetic disease.
CF is characterized by the chronic accumulation of thick mucus in the lungs and digestive tract, causing breathing difficulties, chronic lung infections, and improper digestion of food.
The probability of two carrier parents having a child with CF is 25%. However, not all children born to carrier parents will have CF, as there is also a 75% chance of having a normal child who carries the gene without any symptoms of the disease.