Question

1. Which one of the following cannot be transported into a typical mammalian cell by facilitated transport even though its import might be thermodynamically favored?

A. Na⁺

B. Ca²⁺

C. Fe³⁺

D. H₂O

E. C₆H₁₂O₆

2. What do uniporters and ion channels have in common?

A. Both facilitate transport of molecules down concentration gradients.
B. Both are gated.
C. Both undergo transformations between inward-facing and outward-facing conformations during each transport cycle.
D. Both facilitate transport of molecules against concentration gradients.
E. Both transport molecules at comparable rates.

3. What specifically defines a cotransporter as an antiporter?

A. Both molecules are imported into the cell.
B. Both molecules are exported out of the cell.
C. Both molecules move down their concentration gradients.
D. One molecule is transported against its concentration gradient & the other is transported down its concentration gradient.
E. One molecule is imported and the other molecule is exported.

4. True or False: Transport directed by uniporters is reversible and the direction of of transport will change if the direction of the concentration gradient changes.

True

False