Biology Regents Practice Exam

The correct answer highlights the importance of cell membranes in the context of cystic fibrosis. Cystic fibrosis is caused by mutations in the CFTR gene, which encodes for a protein that functions as a chloride channel in the cell membrane. This protein is crucial for regulating the movement of chloride ions and water in and out of cells. In individuals with cystic fibrosis, the malfunctioning CFTR protein leads to thick, viscous secretions in various organs, particularly in the lungs and digestive system. The impact on the cell membranes is significant because it impairs the proper transport of ions and consequently affects osmotic balance and mucus consistency. This altered ion transport can lead to various complications, such as difficulty in breathing and infections due to mucus buildup in the airways. Other cellular components like nuclei, mitochondria, and ribosomes do not directly relate to the condition caused by the malfunctioning chloride ion channels, making them less relevant in this context. The focus on cell membranes reflects the critical role that ion channels play in maintaining cellular homeostasis and overall function.