Question 1

Which of the following best describes the arrangement of phospholipids in the plasma membrane?

Accepted Answer

Hydrophilic phosphate heads face the interior and exterior of the cell, while hydrophobic fatty acid tails face each other.

Question 2

A red blood cell is placed in a hypertonic solution. What will most likely happen to the cell, and why?

Accepted Answer

The cell will shrink because water moves out of the cell to the area of higher solute concentration.

Question 3

Which of the following processes requires energy in the form of ATP?

Accepted Answer

Active transport

Question 4

During an experiment, dialysis tubing filled with a starch solution is placed in a beaker of water. After 30 minutes, iodine is added to the beaker and the solution inside the tubing turns blue-black. What does this indicate about the movement of molecules?

Accepted Answer

Iodine diffused into the tubing and reacted with starch.

Question 5

Which factor would NOT increase the rate of simple diffusion across a plasma membrane?

Accepted Answer

Increasing the size of the diffusing molecule

Question 6

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Requires specific membrane proteins to transport molecules

Question 7

A cell with a surface area of $$6\ \mathrm{cm}^2$$ and a volume of $$1\ \mathrm{cm}^3 is $$compared to a cell with a surface area of $$24\ \mathrm{cm}^2$$ and a volume of $$8\ \mathrm{cm}^3. $$Which cell is more efficient at diffusion, and why?

Accepted Answer

The smaller cell, because it has a higher surface area to volume ratio.

Question 8

Which of the following best explains why cells are typically small in size?

Accepted Answer

Smaller cells have a higher surface area to volume ratio, allowing for more efficient exchange of materials.

Question 9

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water from low solute concentration to high solute concentration.

Question 10

A cell is placed in an isotonic solution. What will happen to the movement of water across the plasma membrane?

Accepted Answer

There will be no net movement of water across the membrane.

Question 11

Which of the following is an example of active transport in cells?

Accepted Answer

Sodium ions being pumped out of a nerve cell against their concentration gradient

Question 12

Which component of the plasma membrane is primarily responsible for cell recognition and communication?

Accepted Answer

Carbohydrates

Question 13

A dialysis bag containing a solution of reducing sugars is placed in pure water. After 30 minutes, Benedict's reagent is added to the water outside the bag and turns orange. What does this result indicate?

Accepted Answer

Reducing sugars diffused out of the bag into the water.

Question 14

Which of the following best describes the role of membrane proteins in the plasma membrane?

Accepted Answer

They provide stability and facilitate the transport of molecules.

Question 15

If a cell uses ATP to move chloride ions from an area of low concentration to an area of high concentration, which process is occurring?

Accepted Answer

Active transport

Question 16

Which of the following scenarios best illustrates facilitated diffusion?

Accepted Answer

Glucose entering a cell through a specific carrier protein down its concentration gradient

Question 17

A scientist observes that when the temperature of a solution is increased, the rate of diffusion of a solute across a membrane also increases. Which principle does this observation support?

Accepted Answer

Higher temperatures increase the kinetic energy of molecules, increasing diffusion rate.

Question 18

Which of the following equations correctly represents the surface area to volume ratio for a cube-shaped cell with side length $$l$$?

Accepted Answer

$$\frac{6l^2$}{l^3$}$$

Question 19

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It requires ATP to move ions against their concentration gradients.

Question 20

A cell is placed in a solution and water moves into the cell, causing it to swell. Which term best describes the tonicity of the solution relative to the cell?

Accepted Answer

Hypotonic

Plasma Membrane Structure, Diffusion, Osmosis, and Cell Surface Area

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