Q: Which equation best represents the direction of water movement during osmosis?

$$\text{Water moves from regions of low } [\text{solute}] \text{ to regions of high } [\text{solute}]$$

Q: A cell uses ATP to move sodium ions out of the cell against their concentration gradient. What type of transport is this, and what is the general equation for the energy source?

Active transport; $$\text{ATP} \rightarrow \text{ADP} + \text{P}_i$$

Question 1

Which feature of the phospholipid bilayer is primarily responsible for the membrane's fluidity at room temperature?

Accepted Answer

The double bonds in the fatty acid tails preventing close packing

Question 2

A red blood cell is placed in a solution with a lower solute concentration than its cytoplasm. What will happen to the cell, and what is the term for this type of solution?

Accepted Answer

The cell will gain water and burst; the solution is hypotonic

Question 3

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

Cholesterol maintains membrane stability at high temperatures and fluidity at low temperatures

Question 4

Which equation best represents the direction of water movement during osmosis?

Accepted Answer

$$	ext{Water moves from regions of low } [	ext{solute}] 	ext{ to regions of high } [	ext{solute}]$$

Question 5

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

Accepted Answer

Providing a hydrophobic channel for ions

Question 6

A cell uses ATP to move sodium ions out of the cell against their concentration gradient. What type of transport is this, and what is the general equation for the energy source?

Accepted Answer

Active transport; $$	ext{ATP} ightarrow 	ext{ADP} + 	ext{P}_i$$

Question 7

Which process allows a cell to engulf large particles such as bacteria, and what organelle is involved in digesting the engulfed material?

Accepted Answer

Phagocytosis; Lysosome

Question 8

Why do polar molecules require transport proteins to cross the plasma membrane?

Accepted Answer

Because the membrane interior is hydrophobic and repels polar molecules

Question 9

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses transport proteins to move molecules down their concentration gradient

Question 10

A scientist shakes a test tube containing water and phospholipids. What structure will spontaneously form, and why is this significant for the origin of life?

Accepted Answer

Bilayers; they create a separate internal environment

Question 11

Which type of endocytosis is highly specific and involves receptor proteins embedded in the membrane?

Accepted Answer

Receptor-mediated endocytosis

Question 12

What is the main function of integrins in the plasma membrane?

Accepted Answer

To bind the cytoskeleton to the extracellular matrix

Question 13

Which equation best describes the net movement of molecules during diffusion?

Accepted Answer

$$	ext{Net movement from regions of high concentration to regions of low concentration}$$

Question 14

Which of the following is TRUE about aquaporins?

Accepted Answer

They are transport proteins that facilitate the diffusion of water across the plasma membrane

Question 15

A cell is placed in a hypertonic solution. What will happen to the cell, and what is the underlying reason?

Accepted Answer

It will shrivel due to water leaving the cell

Question 16

Which process is used by pancreatic cells to release insulin into the bloodstream?

Accepted Answer

Exocytosis

Question 17

Which of the following best explains why membrane formation was a critical step in the origin of life?

Accepted Answer

Membranes allow for the selective exchange of materials, creating distinct internal environments

Question 18

Which statement about the sodium-potassium pump is correct?

Accepted Answer

It uses ATP to maintain concentration differences of sodium and potassium across the membrane

Question 19

Which of the following is a consequence of the mosaic nature of the plasma membrane?

Accepted Answer

Different cell types have different proteins embedded in their membranes

Question 20

Which process is responsible for the uptake of dissolved nutrients in a non-specific manner by cells?

Accepted Answer

Pinocytosis

Cell Membranes: Structure, Function, and Transport Mechanisms

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