Which of the following statements regarding glucose absorption is true?

• A. Glucose absorption requires direct hydrolysis of ATP at the plasma membrane.
• B. Glucose is absorbed into cells only through endocytosis.
• C. Glucose enters cells by simple diffusion across the lipid bilayer.
• D. Glucose is absorbed into cells via facilitated diffusion using specific transport proteins.

Answer: (D)

Verified step by step guidance

1. Understand the concept of glucose absorption: Glucose is a polar molecule and cannot pass directly through the hydrophobic lipid bilayer of the cell membrane by simple diffusion.
2. Learn about facilitated diffusion: Facilitated diffusion is a passive transport mechanism where molecules move down their concentration gradient with the help of specific transport proteins embedded in the cell membrane.
3. Recognize the role of transport proteins: Glucose absorption involves specialized proteins, such as glucose transporters (GLUT), which bind to glucose molecules and help them cross the membrane without requiring ATP hydrolysis.
4. Clarify why ATP hydrolysis is not required: Facilitated diffusion does not require energy input because it relies on the concentration gradient of glucose rather than active transport mechanisms.
5. Understand why endocytosis is not involved: Endocytosis is a process used for larger molecules or particles, not for small molecules like glucose, which are absorbed through transport proteins.