In the Section "Investigating Life: Does Natural Selection Maintain Cystic

question 34

Multiple Choice

In the section "Investigating Life: Does Natural Selection Maintain Cystic Fibrosis?",one in 25 caucasians is a carrier for the defective CFTR gene,making it the most common genetic disease in this population.Why are the frequency of defects in CFTR so common in caucasians?

• A)Carriers with one copy of the defective CFTR gene have decreased resistance to cholera compared to those with no defective copies.
• B)These individuals were exposed to cholera,causing mutations in their CFTR gene that can then be passed on to their children.
• C)Carriers will be more likely to have children who develop cystic fibrosis.
• D)Carriers with one copy of the defective CFTR gene have increased resistance to cholera compared to those with no defective copies.
• E)Only carriers would be able to survive exposure to cholera.