Homework SoursePart A Which of the following is a characteristic of facilit
Part A
Which of the following is a characteristic of facilitated diffusion (passive transport) of a molecule across a membrane?
| A. It is highly specific for the molecule being transported. |
| B. The rate of transport is saturable. |
| C. The direction of transport is determined by concentration and/or electrochemical gradients. |
| D. Its rate is higher than that of simple diffusion of the molecule. |
| E. All of the above are true. |
Solution
Answer:
E. All of the above are true.
Explanation:
Facilitated transport is a type of passive transport. The materials diffuse across the plasma membrane with the help of membrane proteins until they get saturated. A concentration gradient exists that would allow these materials to diffuse into the cell without expending cellular energy. However, these materials are ions or polar molecules that are repelled by the hydrophobic parts of the cell membrane. Facilitated transport proteins shield these materials from the repulsive force of the membrane, allowing them to diffuse into the cell.
