Question 1

Which of the following best describes the structure of a phospholipid molecule in the plasma membrane?

Accepted Answer

A hydrophilic head and two hydrophobic tails

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which type of solution was the cell placed in, and what is the direction of water movement?

Accepted Answer

Hypotonic; water moves into the cell

Question 3

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Membranes with more unsaturated fatty acids are more fluid at low temperatures

Question 4

Which of the following molecules would most easily diffuse directly through the phospholipid bilayer of a plasma membrane?

Accepted Answer

Oxygen ($\mathrm{O_2}$)

Question 5

A cell uses the sodium-potassium pump to maintain a high concentration of $\mathrm{K^+}$ inside and $\mathrm{Na^+}$ outside. Which type of transport is this, and what is the energy source?

Accepted Answer

Active transport; ATP

Question 6

Which of the following best explains why ions such as $\mathrm{Na^+}$ and $\mathrm{K^+}$ require transport proteins to cross the plasma membrane?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the membrane

Question 7

A plant cell is placed in a hypertonic solution. What will happen to the cell, and what is the term for this process?

Accepted Answer

It will lose water and undergo plasmolysis

Question 8

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

Accepted Answer

Synthesis of phospholipids

Question 9

A neuron releases neurotransmitters into the synaptic cleft by fusing vesicles with the plasma membrane. This process is called:

Accepted Answer

Exocytosis

Question 10

Which of the following best describes the electrochemical gradient across a membrane?

Accepted Answer

It is the combined effect of the ion concentration gradient and the membrane potential

Question 11

Which type of membrane transport is directly driven by the hydrolysis of ATP?

Accepted Answer

Active transport

Question 12

A cell engulfs a bacterium by extending pseudopodia around it and enclosing it in a vacuole. This process is called:

Accepted Answer

Phagocytosis

Question 13

Which of the following scenarios is an example of receptor-mediated endocytosis?

Accepted Answer

A cell taking up cholesterol by binding LDL particles to specific receptors

Question 14

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

Accepted Answer

It moves substances down their concentration gradient without energy input

Question 15

A poison that blocks the function of the sodium-potassium pump would most likely cause which of the following effects in an animal cell?

Accepted Answer

Loss of membrane potential

Question 16

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

Accepted Answer

They function in cell recognition and signaling

Question 17

Which of the following is an example of coupled transport (cotransport) in cells?

Accepted Answer

The movement of $\mathrm{Na^+}$ and glucose into a cell via the same protein

Question 18

Which of the following would most likely increase the rate of osmosis across a cell membrane?

Accepted Answer

Increasing the concentration of aquaporins in the membrane

Question 19

A cell is observed to take in large quantities of fluid and dissolved solutes by forming small vesicles from the plasma membrane. This process is best described as:

Accepted Answer

Pinocytosis

Question 20

Which of the following best explains why the plasma membrane is described as a 'fluid mosaic'?

Accepted Answer

It is a dynamic structure with various proteins embedded in or attached to a fluid phospholipid bilayer

Chapter 7: Membranes – Structure, Function, and Transport in Cells

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