$$\text{Water moves from regions of higher free water concentration to regions of lower free water concentration}$$

Question 1

Which of the following best describes the 'fluid mosaic model' of the plasma membrane?

Accepted Answer

A dynamic structure consisting of a phospholipid bilayer with embedded proteins that can move laterally.

Question 2

A red blood cell is placed in a solution with a higher concentration of nonpenetrating solutes than inside the cell. What will happen to the cell?

Accepted Answer

It will lose water and shrink because the solution is hypertonic.

Question 3

Which property of oxygen ($$O_2) $$and carbon dioxide ($$CO_2) $$allows them to cross the lipid bilayer without the aid of membrane proteins?

Accepted Answer

They are small and nonpolar, allowing them to dissolve in the hydrophobic core.

Question 4

Which equation correctly represents the movement of water during osmosis?

Accepted Answer

$$	ext{Water moves from regions of higher free water concentration to regions of lower free water concentration}$$

Question 5

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It moves solutes down their concentration gradient with the help of transport proteins.

Question 6

The sodium-potassium pump ($$Na^+/K^+$$ pump) is an example of:

Accepted Answer

Active transport using ATP to move ions against their concentration gradients

Question 7

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

Accepted Answer

The cell wall provides structural support and prevents lysis.

Question 8

A Paramecium living in a freshwater pond uses a contractile vacuole to maintain water balance. What is the primary reason for this adaptation?

Accepted Answer

Freshwater is hypotonic to the Paramecium, causing water to enter the cell.

Question 9

Which of the following is true about membrane sidedness?

Accepted Answer

Glycoproteins and glycolipids are found on the extracellular side, originating from the inside face of the ER and Golgi.

Question 10

Which of the following best describes the role of channel proteins in the plasma membrane?

Accepted Answer

They provide hydrophilic pathways for specific molecules to passively diffuse across the membrane.

Question 11

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

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

Question 12

Which of the following equations best represents the electrochemical gradient for an ion?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[C]_{in}}{[C]_{out}} \right) + zF\Delta V$$

Question 13

Which process is responsible for the uptake of large particles, such as bacteria, by a cell?

Accepted Answer

Endocytosis

Question 14

Which of the following statements about cotransport is correct?

Accepted Answer

It couples the movement of one solute down its concentration gradient with the movement of another solute against its gradient.

Question 15

Which of the following is a consequence of the sodium-potassium pump activity in animal cells?

Accepted Answer

The inside of the cell becomes more negative than the outside, establishing membrane potential.

Question 16

Which of the following best explains why facilitated diffusion does not require energy?

Accepted Answer

Solutes move down their concentration gradient, which is a spontaneous process.

Question 17

Which of the following is the main electrogenic pump in plant, fungal, and bacterial cells?

Accepted Answer

Proton pump ($$H^+$$ pump)

Question 18

A glucose transporter protein in the plasma membrane will:

Accepted Answer

Specifically transport glucose, but not fructose, due to its shape and binding specificity.

Question 19

Which of the following best describes the process of plasmolysis in plant cells?

Accepted Answer

The cytoplasm shrivels and the plasma membrane pulls away from the cell wall in a hypertonic environment.

Membrane Structure and Function: Study Notes

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