Q: Which equation best represents the movement of molecules during passive diffusion?

$ \text{Rate} = k \times (C_{\text{high}} - C_{\text{low}}) $

Question 1

Which statement best describes the fluid mosaic model of the cell membrane?

Accepted Answer

The membrane consists of a semi-fluid phospholipid bilayer with proteins and other molecules embedded and able to move laterally.

Question 2

Which of the following is NOT a function of cell membranes?

Accepted Answer

Synthesizing DNA during cell division

Question 3

A cell is placed in a solution containing 22% solute, while the cell itself contains 22% solvent. Which statement is correct regarding tonicity?

Accepted Answer

The cell is isotonic to the solution in the beaker.

Question 4

Which type of membrane protein is most likely to function as a transporter for ions across the membrane?

Accepted Answer

Integral protein

Question 5

Which process requires energy input from ATP to move molecules against their concentration gradient?

Accepted Answer

Active transport

Question 6

What is the main difference between facilitated diffusion and active transport?

Accepted Answer

Facilitated diffusion moves molecules down their concentration gradient without energy input, while active transport moves molecules against the gradient using energy.

Question 7

Which of the following best describes osmosis?

Accepted Answer

Passive diffusion of water across a semipermeable membrane from a region of low solute concentration to high solute concentration

Question 8

A red blood cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

It will gain water and swell, possibly lysing.

Question 9

Which of the following is a real-world example of a defect in an integral membrane protein causing disease?

Accepted Answer

Cystic fibrosis due to a defective CFTR ion channel

Question 10

Which statement about phospholipids in the cell membrane is correct?

Accepted Answer

Phospholipids form a bilayer with hydrophilic heads facing outwards and hydrophobic tails facing inwards.

Question 11

Which type of endocytosis is responsible for the uptake of cholesterol into cells?

Accepted Answer

Receptor-mediated endocytosis

Question 12

What is the role of cholesterol in animal cell membranes?

Accepted Answer

It stabilizes the membrane at various temperatures.

Question 13

Which equation best represents the movement of molecules during passive diffusion?

Accepted Answer

$ 	ext{Rate} = k 	imes (C_{	ext{high}} - C_{	ext{low}}) $

Question 14

Which of the following transport systems moves two substances in opposite directions across the membrane?

Accepted Answer

Antiport

Question 15

Which process is used by cells to release large molecules, such as hormones, outside the cell?

Accepted Answer

Exocytosis

Question 16

What is the effect of a hypertonic solution on a plant cell?

Accepted Answer

The cell will lose water and the membrane will pull away from the cell wall (plasmolysis).

Question 17

Which of the following best describes an amphipathic molecule?

Accepted Answer

A molecule that has both hydrophilic and hydrophobic regions

Question 18

Which membrane transport process is most directly involved in nerve cell signaling?

Accepted Answer

Electrogenic pumps generating membrane potential

Question 19

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses specific protein channels to move molecules down their concentration gradient.

Question 20

A cell uses the sodium-potassium pump to maintain ion gradients. Which equation best represents the energy change involved in this process?

Accepted Answer

$ \Delta G = \Delta G^\circ + RT \ln \left( \frac{[	ext{Na}^+]_{	ext{out}}}{[	ext{Na}^+]_{	ext{in}}} ight) $

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