Final answer:
Cystic fibrosis causes the absence of chloride ions in mucus secretions, resulting in thick and sticky mucus that is difficult to remove from the respiratory system. This leads to blockage of passageways and makes it easier for bacterial infections to occur.
Step-by-step explanation:
In individuals with cystic fibrosis (CF), the absence of the CFTR channel prevents the transportation of chloride ions out of the cell, leading to a lack of positive ions in the secreted mucus. As a result, there is no osmotic pressure pulling water into the mucus, causing it to be thick and sticky.
The ciliated epithelia in the respiratory system cannot effectively remove this mucus, leading to the blockage of passageways and the accumulation of debris. This makes it easier for bacterial infections to occur as bacterial cells are not effectively carried away from the lungs.