Q: Which equation best represents the process of osmosis?

$$ \text{H}_2\text{O} \text{ moves from an area of low solute concentration to high solute concentration across a semipermeable membrane} $$

Question 1

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

Accepted Answer

A flexible bilayer of phospholipids with proteins and cholesterol molecules that can move laterally within the layer.

Question 2

A red blood cell is placed in a hypotonic solution. What will most likely happen to the cell, and why?

Accepted Answer

It will swell and possibly burst because water will move into the cell by osmosis.

Question 3

Which of the following is an example of active transport across a cell membrane?

Accepted Answer

Pumping sodium ions out of the cell against their concentration gradient using ATP.

Question 4

Which equation best represents the process of osmosis?

Accepted Answer

$$ 	ext{H}_2	ext{O} 	ext{ moves from an area of low solute concentration to high solute concentration across a semipermeable membrane} $$

Question 5

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses membrane proteins to help substances move down their concentration gradient.

Question 6

A plant cell is placed in a hypertonic solution. What is the expected outcome for the cell?

Accepted Answer

The cell will become flaccid and may undergo plasmolysis as water leaves.

Question 7

Which of the following best distinguishes between channel proteins and active transporters?

Accepted Answer

Channel proteins allow passive movement of molecules down their concentration gradient, while active transporters move molecules against their gradient using energy.

Question 8

Which of the following is a function of gap junctions in animal cells?

Accepted Answer

They allow direct communication and transfer of small molecules between adjacent cells.

Question 9

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

Accepted Answer

Phagocytosis

Question 10

A scientist observes that a certain molecule crosses the plasma membrane rapidly without the use of a transport protein. Which property is most likely true of this molecule?

Accepted Answer

It is small and nonpolar.

Question 11

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It stabilizes membrane fluidity at different temperatures.

Question 12

Which of the following scenarios best illustrates the process of exocytosis?

Accepted Answer

A vesicle containing neurotransmitters fuses with the plasma membrane to release its contents outside the cell.

Question 13

Which of the following equations best represents the net movement of water during osmosis?

Accepted Answer

$$ 	ext{Net movement of H}_2	ext{O} = 	ext{from region of higher free water concentration to region of lower free water concentration} $$

Question 14

Which of the following is true about plasmodesmata in plant cells?

Accepted Answer

They are channels that connect the cytoplasm of adjacent plant cells, allowing the passage of small molecules.

Question 15

A cell uses ATP to move potassium ions into the cell and sodium ions out of the cell. Which type of transport is this, and what is the main reason it is necessary?

Accepted Answer

Active transport; to maintain electrochemical gradients essential for cell function.

Question 16

Which of the following best describes the role of aquaporins in the cell membrane?

Accepted Answer

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

Question 17

A cell is placed in an isotonic solution. What will happen to the cell's volume over time?

Accepted Answer

It will remain the same because there is no net movement of water.

Question 18

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

Accepted Answer

Active transport moves substances against their concentration gradient, while passive transport moves substances down their concentration gradient.

Question 19

Which of the following best explains why ions such as Na	extsuperscript{+} and K	extsuperscript{+} cannot easily cross the lipid bilayer without assistance?

Accepted Answer

They are hydrophilic and charged, so they cannot pass through the hydrophobic core of the membrane.

Question 20

A patient is given an intravenous solution that is hypertonic relative to their blood cells. What is the most likely effect on the patient's red blood cells?

Accepted Answer

The cells will shrink as water leaves them.

The Working Cell: Membrane Structure, Function, and Transport

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