Question 1

Which property of phospholipids is most responsible for the formation of the lipid bilayer in cellular membranes?

Accepted Answer

Their amphipathic nature, having both hydrophilic heads and hydrophobic tails

Question 2

A scientist observes that a certain cell membrane remains fluid even at very low temperatures. Which adaptation most likely explains this observation?

Accepted Answer

A high proportion of unsaturated fatty acid tails in the membrane phospholipids

Question 3

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

Accepted Answer

It stabilizes membrane fluidity across a range of temperatures

Question 4

Which of the following molecules would most easily diffuse directly across the lipid bilayer without a transport protein?

Accepted Answer

Small nonpolar oxygen gas

Question 5

Facilitated diffusion differs from simple diffusion because it:

Accepted Answer

Uses a transport protein to help large, polar, or charged molecules cross the membrane, still moving down their concentration gradient

Question 6

If a plant cell is placed in a hypertonic solution, what will happen to the cell?

Accepted Answer

Water will move out of the cell, potentially causing plasmolysis

Question 7

Turgor pressure, essential for keeping plants upright, is best described as:

Accepted Answer

The force of water pushing against the inside of the cell wall

Question 8

Which of the following best explains why animal cells burst in a hypotonic solution but plant cells do not?

Accepted Answer

Plant cells have a rigid cell wall that prevents excessive expansion

Question 9

The sodium-potassium pump is an example of active transport because it:

Accepted Answer

Uses ATP to move sodium and potassium ions against their concentration gradients

Question 10

The electrochemical gradient across a membrane is best defined as:

Accepted Answer

The combined force of the concentration gradient and the membrane's voltage (membrane potential)

Question 11

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Facilitating cell-cell recognition

Question 12

Which process allows a cell to engulf a large particle by extending pseudopods to form a food vacuole?

Accepted Answer

Phagocytosis

Question 13

How does receptor-mediated endocytosis differ from pinocytosis?

Accepted Answer

Receptor-mediated endocytosis allows the cell to acquire specific substances via binding to specific receptors, while pinocytosis nonspecifically takes in extracellular fluid

Question 14

A patient with familial hypercholesterolemia has high blood cholesterol because:

Accepted Answer

Their cells lack the receptors needed for LDL uptake by receptor-mediated endocytosis

Question 15

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

Accepted Answer

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

Question 16

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

Accepted Answer

Synthesizing DNA

Question 17

A red blood cell placed in a hypotonic solution will:

Accepted Answer

Gain water and may burst due to lack of a cell wall

Question 18

Which of the following best explains why oxygen and carbon dioxide can easily cross the plasma membrane?

Accepted Answer

They are small and nonpolar molecules

Question 19

Which of the following best describes cotransport?

Accepted Answer

A membrane protein couples the passive transport of one ion to the active transport of another molecule

Question 20

Which of the following is a real-life example of receptor-mediated endocytosis?

Accepted Answer

Uptake of LDL cholesterol by liver cells

Membrane Structure and Function: Study Notes for General Biology

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