Question 1

Which of the following best describes the structure of a biological membrane?

Accepted Answer

A bilayer with hydrophobic tails facing each other and hydrophilic heads facing outward

Question 2

Which type of molecule can most easily cross a cell membrane without the help of a protein?

Accepted Answer

Small uncharged molecules

Question 3

Passive transport relies on which of the following gradients to move solutes across membranes?

Accepted Answer

Concentration gradient and electrical gradient

Question 4

Which equation best represents the rate of diffusion for a solute across a membrane?

Accepted Answer

$$D = k 	imes (C_1$ - C_2$)$$

Question 5

A cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will shrink as water leaves the cell

Question 6

Which of the following is NOT a feature of facilitated diffusion?

Accepted Answer

Requires energy from ATP

Question 7

Which of the following best describes the function of a proton pump in active transport?

Accepted Answer

It moves protons against their concentration gradient using ATP

Question 8

A carrier protein undergoes several steps during facilitated diffusion. Which sequence is correct?

Accepted Answer

Unbound protein $$\rightarrow$$ substrate binding $$\rightarrow$$ conformational change $$\rightarrow$$ release

Question 9

Which of the following is true about secondary active transport?

Accepted Answer

It uses the energy stored in an ion gradient to transport another substance

Question 10

If a cell is placed in an isotonic solution, what will happen to the movement of water?

Accepted Answer

Water will move equally in and out of the cell

Question 11

Which of the following best explains why ions cannot easily cross the lipid bilayer?

Accepted Answer

Ions are hydrophilic and the bilayer interior is hydrophobic

Question 12

Which of the following is a consequence of increasing cell size for membrane transport?

Accepted Answer

Surface area to volume ratio decreases, making transport less efficient

Question 13

Which of the following is true about gated channels in facilitated diffusion?

Accepted Answer

They open or close in response to specific signals

Question 14

Which equation best describes the Nernst potential for an ion across a membrane?

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion outside}]}{[	ext{ion inside}]} ight)$$

Question 15

Which of the following is an example of a symporter in secondary active transport?

Accepted Answer

A protein that moves glucose and sodium into the cell together

Question 16

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water across a semi-permeable membrane from low solute concentration to high solute concentration

Question 17

A patient receives an intravenous solution that is hypotonic compared to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

Red blood cells will swell and may burst

Question 18

Which of the following is true about equilibrium in diffusion?

Accepted Answer

There is no net movement of solute across the membrane

Question 19

Which of the following best describes the difference between concentration gradient and electrical gradient?

Accepted Answer

Concentration gradient is based on solute amount, electrical gradient is based on charge difference

Question 20

Which of the following is a real-world example of active transport in human physiology?

Accepted Answer

The sodium-potassium pump maintaining nerve cell resting potential

Membrane Structure and Transport Mechanisms

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