Advanced Placement (AP) Biology Practice Exam

What is the function of aquaporins in bacterial cells?

1. Facilitating nutrient uptake

2. Transporting ions across the membrane

3. Acting as water channels

4. Sorting proteins for secretion

The correct answer is: Acting as water channels

Aquaporins serve as specialized water channels in the membranes of bacterial cells, playing a crucial role in facilitating the rapid movement of water molecules across the cell membrane. These proteins enable bacteria to maintain osmotic balance and respond swiftly to changes in environmental conditions, such as fluctuations in water availability. The presence of aquaporins ensures that bacterial cells can efficiently manage water transport, which is vital for processes like cell turgor maintenance, nutrient transport, and waste removal. Their specific structural characteristics allow them to selectively transport water while restricting the passage of ions and other solutes. Understanding the role of aquaporins highlights their importance in cellular homeostasis and adaptation to varying hydration states, emphasizing why they are integral components of bacterial physiology.