Cystic fibrosis

Hi, can someone explain why statement 1 is wrong? The answer is A

A person with cystic fibrosis is told that they have inherited alleles that code for a non-functional CFTR protein. This means that chloride ions are unable to diffuse out of the epithelial cells through this protein. Chloride ions accumulate within the cells, altering the water potential in the cytoplasm. This change in water potential will affect the mucus in the airways and lead to coughing and increased risk of chest infection.

Which of the following statements describe the effects of a non-functional CFTR protein in the epithelial cells in the lungs?

  1. The water potential in the epithelial cells is higher than in similar cells with a functional CFTR protein.
  2. The mucus in the lungs becomes thick and sticky and it is difficult for cilia to sweep it up towards the mouth.
  3. Water is unable to move by osmosis out of the epithelial cells into the mucus coating the cells.

A 2and3only
B 1only
C 1and2only
D 1and3only
E 1,2and3

In option 1, the water potential is actually low, meaning water molecules have very low tendency to leave the cell because they want to stay in the cell due to high osmolarity imposed by chlorine ions.

1 Like