Why does glucose require a channel/carrier protein to cross the bilayer despite moving down its gradient?
- A
Glucose is positively charged and repelled by phospholipid heads
- B
Glucose is too small to be detected
- C
Glucose binds water tightly and only crosses with ATP
- Dcheck_circle
Glucose is large and polar; the hydrophobic core blocks unaided diffusion
Explanation
Polar/large solutes like glucose cannot pass through the hydrophobic membrane interior; protein carriers (e.g., GLUT) provide a hydrophilic path down the gradient.