Question 1

Which of the following best explains why unsaturated fatty acids increase membrane fluidity at lower temperatures?

Accepted Answer

The double bonds in unsaturated fatty acids form kinks in the tails, preventing tight packing.

Question 2

A cell is placed in a solution containing 80% solute and 20% solvent, while the inside of the cell contains 30% solute and 70% solvent. What will happen to the cell?

Accepted Answer

The cell will shrink because water will move out of the cell.

Question 3

Which of the following molecules can most easily cross the hydrophobic core of the plasma membrane without assistance?

Accepted Answer

Oxygen ($$O_2)$$

Question 4

What is the primary function of cholesterol in the plasma membrane?

Accepted Answer

It stabilizes membrane fluidity across temperature changes.

Question 5

A red blood cell is placed in a hypotonic solution. What is the expected outcome?

Accepted Answer

The cell will swell and may burst due to water gain.

Question 6

Which statement best describes an integral membrane protein?

Accepted Answer

It is amphipathic, with at least one hydrophobic region localized to the interior of the membrane.

Question 7

A plant cell is placed in distilled water. What will happen to the cell and why?

Accepted Answer

Water will move into the cell, increasing turgor pressure until equilibrium is reached.

Question 8

Which type of transport requires energy to move molecules against their concentration gradient?

Accepted Answer

Active transport

Question 9

Given the solute potential equation $$\Psi_s = -iCRT$$, what is the solute potential of a 0.1 M sucrose solution at 22°C? ($$i = 1$$, $$R = 0.0831 L$$·bar/mol·K, $$T = 295 K)$$

Accepted Answer

$$\Psi_s = -2.45$$ bars

Question 10

A cell with a pressure potential of 3 bars and a solute potential of $$-4.5$$ bars is placed in a solution with a solute potential of $$-4.0$$ bars and zero pressure potential. What is the net direction of water movement?

Accepted Answer

Water will move out of the cell.

Question 11

Which process allows cells to take up large molecules that are present in low concentrations in the extracellular fluid?

Accepted Answer

Receptor-mediated endocytosis

Question 12

If you drink seawater with a solute potential of $$-2.0$$ bars, what will happen to your body's cells?

Accepted Answer

Water will move out of your cells, causing them to shrink.

Question 13

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Maintaining membrane fluidity

Question 14

A U-tube experiment has side A with 2 M sucrose and 1 M glucose, and side B with 2 M glucose. The membrane is permeable to water but not to sugars. What will happen to the water level after equilibrium?

Accepted Answer

Water will move from side B to side A, raising the level on side A.

Question 15

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient via membrane proteins without energy input.

Question 16

Which scenario would result in plasmolysis in a plant cell?

Accepted Answer

Placing the cell in a hypertonic solution.

Question 17

Which of the following is a real-life example of passive transport?

Accepted Answer

Oxygen ($$O_2) $$diffusing into red blood cells from the lungs.

Question 18

Which equation correctly represents the total water potential ($$\Psi) in a $$plant cell?

Accepted Answer

$$\Psi = \Psi_s + \Psi_p$$

Question 19

Which of the following statements about the phospholipid bilayer is correct?

Accepted Answer

The hydrophobic tails face each other in the interior of the membrane.

Cell Membranes & Transport: Structure and Function

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