Q: Which equation best represents the hydrolysis of ATP that powers active transport?

$$ \mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy} $$

Question 1

Which of the following best describes the main structural difference between integral and peripheral membrane proteins?

Accepted Answer

Integral membrane proteins are embedded within the phospholipid bilayer, while peripheral membrane proteins are attached to the surface of the membrane.

Question 2

Which of the following molecules would diffuse most rapidly across a pure phospholipid bilayer, according to the permeability scale?

Accepted Answer

O$$_2$$

Question 3

A cell is placed in a solution with a higher concentration of solute than inside the cell. What will happen to the water movement, and what is this process called?

Accepted Answer

Water will move out of the cell by osmosis.

Question 4

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

Facilitated diffusion requires a membrane protein and moves substances down their electrochemical gradient.

Question 5

Which of the following best explains why the Na$$^+/K$^+$$ pump is considered an example of primary active transport?

Accepted Answer

It directly uses ATP to move ions against their electrochemical gradients.

Question 6

Which equation best represents the hydrolysis of ATP that powers active transport?

Accepted Answer

$$ \mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy} $$

Question 7

A mutation causes a potassium channel to lose its selectivity. Which of the following is a likely consequence?

Accepted Answer

Other ions, such as Na$$^+$$, may pass through the channel, disrupting the cell's electrochemical gradient.

Question 8

Which of the following is NOT a factor that affects the rate of facilitated diffusion?

Accepted Answer

The amount of ATP available.

Question 9

Which of the following best describes the function of aquaporins?

Accepted Answer

They facilitate the rapid movement of water molecules across the membrane.

Question 10

Which of the following is true about secondary active transport (co-transport)?

Accepted Answer

It uses the energy stored in an electrochemical gradient established by primary active transport.

Question 11

A cell is exposed to a toxin that inhibits all ATP production. Which of the following processes would be LEAST affected?

Accepted Answer

Diffusion of O$$_2$$ across the membrane.

Question 12

Which of the following best explains why the Na$$^+/K$^+$$ pump is essential for nerve cell function?

Accepted Answer

It establishes the electrochemical gradient necessary for action potentials.

Question 13

Which of the following is a correct comparison between the Na$$^+/K$^+$$ pump in animal cells and the H$$^+$$ pump in plant cells?

Accepted Answer

Both establish electrochemical gradients, but the Na$$^+/K$^+$$ pump moves Na$$^+$$ and K$$^+$$, while the H$$^+$$ pump moves protons.

Question 14

Which of the following best describes the role of a symporter in secondary active transport?

Accepted Answer

It moves two molecules in the same direction, one against and one along its gradient.

Question 15

A patient with cystic fibrosis has a mutation in a chloride channel. Which of the following best explains the physiological consequence?

Accepted Answer

Impaired chloride transport disrupts water movement, leading to thick mucus.

Question 16

Which of the following is a property of gated channels?

Accepted Answer

They open or close in response to specific signals, such as voltage or ligand binding.

Question 17

Which of the following best describes the movement of glucose into a cell via GLUT-1?

Accepted Answer

Glucose binds to GLUT-1, causing a conformational change that allows glucose to enter the cell by facilitated diffusion.

Question 18

Which of the following is a key difference between passive and active transport?

Accepted Answer

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

Question 19

Which of the following best explains why the Na$$^+/K$^+$$ pump must have many hydrophobic alpha-helices?

Accepted Answer

Hydrophobic alpha-helices allow the pump to span the hydrophobic core of the phospholipid bilayer.

Membrane Structure and Transport Mechanisms in Eukaryotic Cells

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