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In a hypothetical cell, the facilitated diffusion of a solute 'Y' is observed to be significantly faster than predicted by simple diffusion models. However, the transport rate plateaus at high concentrations of Y. Which of the following is the MOST likely explanation for this observation?
The cell membrane is selectively permeable to Y.
The solute Y is transported via carrier proteins.
The solute Y is undergoing active transport.
The cell is modifying Y during transport.
Which of the following statements regarding facilitated diffusion is INCORRECT?
It requires transport proteins.
It is a passive process and does not require energy.
It can move molecules against their concentration gradient.
Transport proteins involved can become saturated.
A plant cell is placed in a solution with a water potential of -0.8 MPa. The cell's initial solute potential is -1.2 MPa and its pressure potential is 0.4 MPa. After equilibration, which of the following statements about the cell's state is MOST accurate?
The cell will be turgid, with a pressure potential greater than 0.4 MPa.
The cell will be flaccid, with a pressure potential of zero.
The cell will be plasmolyzed, with a pressure potential of zero.
The cell will experience incipient plasmolysis, with a pressure potential slightly above zero.
Which of the following conditions would likely INHIBIT plasmolysis in a plant cell?
Increasing the concentration of solutes in the external solution.
Placing the cell in a hypertonic solution.
Placing the cell in a hypotonic solution.
Decreasing the cell's internal solute concentration.
During plasmolysis, the cell membrane separates from the cell wall. This separation is primarily due to:
The expansion of the cell wall due to increased turgor pressure.
The shrinking of the protoplast due to water loss.
The breakdown of the cell wall by hydrolytic enzymes.
The active transport of water out of the cell.
Imagine a plant cell undergoing plasmolysis. If the external solution's water potential is further decreased, which of the following is the MOST likely consequence?
Deplasmolysis and return to a turgid state.
Incipient plasmolysis with the cell membrane just touching the cell wall.
No further change in the cell's state.
Increased plasmolysis with further shrinkage of the protoplast.
A plant cell with a water potential of -0.6 MPa is placed in a solution. After a period of time, the cell reaches equilibrium and is found to be plasmolyzed. Which of the following values could represent the water potential of the solution?
-0.4 MPa
-0.6 MPa
-0.8 MPa
-0.2 MPa
Which of the following is NOT a direct consequence of plasmolysis in plant cells?
Reduction in turgor pressure
Separation of the plasma membrane from the cell wall
Shrinkage of the protoplast
Lysis of the cell
A dry wooden block and a dry gelatine block of equal mass are placed in water. The gelatine block imbibes considerably more water than the wooden block. This difference is primarily attributed to:
The higher density of wood compared to gelatine.
The greater number of hydrophilic colloids in gelatine compared to wood.
The presence of lignin in wood, which repels water.
The lower osmotic potential of gelatine compared to wood.
The pressure required to prevent the swelling of a gelatine block when immersed in water is called:
Osmotic pressure
Turgor pressure
Wall pressure
Imbibition pressure
