Question 1

Which of the following best explains why the plasma membrane is described as 'selectively permeable'?

Accepted Answer

It allows certain molecules to enter or leave the cell while restricting others based on size, polarity, and the presence of specific transport proteins.

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 statements about facilitated diffusion is correct?

Accepted Answer

Facilitated diffusion moves molecules down their concentration gradient with the help of specific membrane proteins, without using energy.

Question 4

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

Accepted Answer

Hydrophilic phosphate heads face both the inside and outside of the cell, while hydrophobic fatty acid tails face each other within the membrane.

Question 5

A dialysis tubing 'cell' filled with starch and placed in a solution containing iodine turns blue-black after 30 minutes. What does this indicate about the movement of molecules?

Accepted Answer

Iodine diffused into the tubing and reacted with starch inside.

Question 6

Which equation correctly represents the relationship between surface area (SA) and volume (V) for a spherical cell, and why is this relationship important?

Accepted Answer

$$SA = 4\pi r^2$, V$$ = \frac{4}{3}\pi $$r^3$$; as cells grow, volume increases faster than surface area, limiting efficient diffusion.$

Question 7

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

Accepted Answer

Active transport

Question 8

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

Question 9

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

Accepted Answer

Increasing the size of the diffusing molecules

Question 10

Why do cells need to remain small in size, according to the surface area to volume ratio concept?

Accepted Answer

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

Question 11

Which of the following best describes osmosis?

Accepted Answer

The movement of water molecules from an area of low solute concentration to an area of high solute concentration across a semipermeable membrane.

Question 12

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

Accepted Answer

Carbohydrates

Question 13

A patient is given an intravenous (IV) solution that is hypotonic relative to their blood cells. What is the most likely outcome for the patient's red blood cells?

Accepted Answer

The cells will swell and may burst as water enters the cells.

Question 14

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

Accepted Answer

Sodium ions being pumped out of a cell against their concentration gradient using ATP.

Question 15

During a lab experiment, you observe that chloride ions are present outside a dialysis tubing 'cell' but not inside after 30 minutes. What does this suggest about the membrane's properties?

Accepted Answer

The membrane is impermeable to chloride ions.

Question 16

Which of the following best explains why large molecules like proteins require facilitated diffusion or active transport to cross the plasma membrane?

Accepted Answer

Large molecules are too big to pass through the lipid bilayer and require specific membrane proteins for transport.

Question 17

Which of the following scenarios best illustrates the concept of tonicity?

Accepted Answer

A plant cell placed in pure water becomes turgid as water enters the cell.

Question 18

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

Accepted Answer

Storing genetic information

Question 19

If a cell's surface area is $$100 \ \mu m^2$ and its volume is 125$$ \ \mu $$m^3$$, what is its surface area to volume ratio, and why is this ratio important?

Accepted Answer

$$0.8$$, which means the cell may have difficulty efficiently exchanging materials with its environment as it grows larger.

Question 20

Which of the following best describes the movement of water in osmosis?

Accepted Answer

Water moves from an area of low solute concentration to high solute concentration.

Cell Membranes, Diffusion, and Osmosis: Structure and Function

Study Guide - Practice Questions

Study Guide - Flashcards