Question 1

Which of the following best describes the structure of the plasma membrane in eukaryotic cells?

Accepted Answer

A double layer of phospholipids with hydrophilic heads facing outward and hydrophobic tails facing inward

Question 2

A red blood cell is placed in a solution and begins to swell and eventually bursts. Which term best describes the tonicity of the solution relative to the cell cytoplasm?

Accepted Answer

Hypotonic

Question 3

Which of the following statements about simple diffusion is correct?

Accepted Answer

It moves molecules from high to low concentration without energy input.

Question 4

Which factor would most likely increase the rate of diffusion of oxygen across a cell membrane?

Accepted Answer

Increasing the concentration gradient of oxygen

Question 5

A dialysis bag 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 bag turns blue-black. What does this indicate about the movement of molecules?

Accepted Answer

Iodine diffused into the bag and reacted with starch

Question 6

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 more efficient diffusion of materials.

Question 7

Which process requires the use of ATP to move molecules across the plasma membrane?

Accepted Answer

Active transport

Question 8

A cell is placed in a hypertonic solution. What will most likely happen to the cell?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 9

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses specific membrane proteins to move molecules down their concentration gradient.

Question 10

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Active transport

Question 11

If a cell's surface area is $$6 \ \mathrm{cm}^2$$ and its volume is $$1 \ \mathrm{cm}^3$$, what is its surface area to volume ratio?

Accepted Answer

$$6:1$$

Question 12

Which of the following best describes osmosis?

Accepted Answer

The movement of water from low solute concentration to high solute concentration

Question 13

A patient receives an intravenous (IV) solution that is isotonic to their blood plasma. What effect will this have on their red blood cells?

Accepted Answer

There will be no net movement of water into or out of the cells.

Question 14

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

Accepted Answer

Carbohydrates

Question 15

A scientist observes that a certain molecule cannot cross the plasma membrane by simple diffusion but does move across when a specific protein is present. Which process is most likely responsible?

Accepted Answer

Facilitated diffusion

Question 16

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

Accepted Answer

Increasing the size of the diffusing molecule

Question 17

In a dialysis experiment, which result would indicate that a solute was too large to cross the semipermeable membrane?

Accepted Answer

The solute is only detected inside the dialysis bag after the experiment.

Question 18

Which of the following best explains why facilitated diffusion is considered a passive process?

Accepted Answer

It moves molecules down their concentration gradient without using cellular energy.

Question 19

A cell uses ATP to move chloride ions from an area of low concentration to an area of high concentration. Which equation best represents the energy requirement for this process?

Accepted Answer

$$\mathrm{ATP} ightarrow \mathrm{ADP} + \mathrm{P} + 	ext{energy}$$

Question 20

Which of the following scenarios best illustrates the importance of surface area to volume ratio in cells?

Accepted Answer

A large cell divides into two smaller cells to increase efficiency of nutrient uptake.

Plasma Membrane Structure, Diffusion, Osmosis, and Cell Size

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