A human gene called the CFTR gene (for cystic fibrosis transmembrane regulator) encodes a protein that functions in the transport of chloride ions across the cell membrane. Most people have two copies of a functional CFTR gene and do not have cystic fibrosis. However,  mutant version of the CFTR gene is found in some people. If a person has two mutant copies of the gene, he or she develops the disease known as cystic fibrosis. Are the following descriptions of this disease related to genetics at the molecular, cellular, organism, or population level?