Q: The sodium-potassium pump moves ions against their concentration gradients. Which equation best represents the energy input required for this process?

$ATP \rightarrow ADP + P_i + \text{energy}$

Question 1

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

Accepted Answer

A dynamic bilayer of phospholipids with proteins and carbohydrates embedded, allowing lateral movement.

Question 2

What is the primary function of cholesterol in animal cell membranes at moderate temperatures?

Accepted Answer

It decreases membrane fluidity by restraining phospholipid movement.

Question 3

A red blood cell is placed in a solution with a lower solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

Water will enter the cell, causing it to swell and possibly lyse.

Question 4

Which equation best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$\Delta \Psi = \Psi_{inside} - \Psi_{outside}$

Question 5

Which type of membrane protein is most likely to function as a channel for ions?

Accepted Answer

Integral transmembrane protein

Question 6

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion uses transport proteins to move substances down their concentration gradient.

Question 7

Which of the following molecules can most easily cross the lipid bilayer without a transport protein?

Accepted Answer

Oxygen ($O_2$)

Question 8

A plant cell in a hypertonic solution will most likely:

Accepted Answer

Undergo plasmolysis as water leaves the cell.

Question 9

The sodium-potassium pump moves ions against their concentration gradients. Which equation best represents the energy input required for this process?

Accepted Answer

$ATP ightarrow ADP + P_i + 	ext{energy}$

Question 10

Which process is responsible for the uptake of cholesterol into animal cells?

Accepted Answer

Receptor-mediated endocytosis

Question 11

What is the main difference between active and passive transport across the plasma membrane?

Accepted Answer

Active transport requires energy input, while passive transport does not.

Question 12

Which of the following best describes the role of membrane carbohydrates?

Accepted Answer

They serve as markers for cell recognition.

Question 13

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

Accepted Answer

There will be no net movement of water; the cell remains unchanged.

Question 14

Which of the following is a function of bulk transport in cells?

Accepted Answer

Movement of large molecules such as proteins and polysaccharides via vesicles.

Question 15

Which type of endocytosis is non-specific for the substances it transports?

Accepted Answer

Pinocytosis

Question 16

Which of the following statements about membrane potential is correct?

Accepted Answer

It favors passive transport of cations into the cell and anions out of the cell.

Question 17

Which of the following best explains why unsaturated fatty acids increase membrane fluidity at low temperatures?

Accepted Answer

Their kinks prevent tight packing, maintaining fluidity.

Question 18

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

Accepted Answer

Exocytosis

Question 19

Which equation best represents the electrochemical gradient driving ion movement across membranes?

Accepted Answer

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

Question 20

Which of the following is true about transport proteins in the plasma membrane?

Accepted Answer

They are highly specific, often transporting only one type of molecule.

Membrane Structure and Function: Study Notes (Campbell Biology, Chapter 7)

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