Transport Mechanism

Multiple Choice

Which of the following statements about passive transport is correct?

• Passive transport operates independently of the concentrations of the moving solute.

• Passive transport permits the solute to move in either direction, but the net movement of solute molecules occurs down the concentration gradient of the molecule.

• Passive transport operates independently of diffusion.

• In passive transport, solute movement stops when the solute concentration is the same on both sides of the membrane.

Multiple Choice

Which of the following statements about diffusion is true?

• It is a passive process.

• It occurs when molecules move from a region of lower concentration to a region of higher concentration.

• It involves only the movement of water molecules.

• It requires expenditure of energy by the cell.

Multiple Choice

A single plant cell is placed in an isotonic solution. Salt is then added to the solution. Which of the following would occur as a result of the salt addition?

• The added salt makes the solution hypotonic compared to the cell. Water will enter the cell by osmosis.

• The added salt would enter the cell, causing the cell to take up water and swell.

• Water would enter the cell by osmosis, and the cell would swell.

• 
  Water would leave the cell by osmosis, causing the volume of the cytoplasm to decrease.

Multiple Choice

Seawater is hypertonic to cytoplasm in vertebrate cells and in plant cells. If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

• The red blood cell would burst, and the plant cell would shrink.

• The red blood cell would shrink, and the plant cell would gain water.

• Both cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall.

• Both cells would gain water by osmosis; the red blood cell would burst, and the plant cell would increase in turgor pressure.

Multiple Choice

Which of the following is a correct difference between active transport and facilitated diffusion?

• Active transport requires energy from ATP, and facilitated diffusion does not.

• Active transport involves transport proteins, and facilitated diffusion does not.

• Facilitated diffusion involves transport proteins, and active transport does not.

• Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot.

Multiple Choice

Which of the following pairs correctly matches a membrane transport process to its primary function?

• pinocytosis: the uptake of water and small solutes into the cell by formation of vesicles at the plasma membrane

• exocytosis: the movement of water and solutes out of the cell by passage through the plasma membrane

• phagocytosis: secretion of large particles from the cell by fusion of vesicles with the plasma membrane

• osmosis: passive diffusion of water and small solutes across a membrane