Step-by-step explanation:
Cystic fibrosis is a genetic disease caused by a mutation in the CFTR gene. The CFTR gene is involved in the formation of certain ABC channels in the membrane which are involved in the influx and efflux of the chloride ions in the cell.
The disease is caused when both the copies of the mutated genes each from father and mother are present in the progeny that is it is caused by the recessive allele.
The person with a normal allele of CFTR genes is normal and does not develop the affected organs like the lungs, kidney, pancreas, and others but a person with the mutated genes form a thick mucus in their organs especially the lungs but also in the kidney, pancreas.