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

$$ \text{Net movement} = \text{High concentration} \rightarrow \text{Low concentration} $$

Question 1

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

Accepted Answer

A dynamic structure with proteins, lipids, and carbohydrates constantly moving within a bilayer.

Question 2

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

Accepted Answer

To prevent tight packing of phospholipids at cool temperatures, maintaining fluidity.

Question 3

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

Accepted Answer

It will lose water and shrivel as water moves out.

Question 4

Which type of membrane protein is embedded in the hydrophobic core of the lipid bilayer and often spans the entire membrane?

Accepted Answer

Integral protein

Question 5

Which process describes the movement of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 6

Winter wheat modifies its cell membranes in cold weather by increasing the proportion of unsaturated fatty acids. What is the biological advantage of this adaptation?

Accepted Answer

It increases membrane fluidity, preventing solidification at low temperatures.

Question 7

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Providing structural support to the cell wall

Question 8

A red blood cell is placed in pure water. Which of the following best describes what happens?

Accepted Answer

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

Question 9

Which equation correctly represents the movement of molecules during diffusion?

Accepted Answer

$$ 	ext{Net movement} = 	ext{High concentration} ightarrow 	ext{Low concentration} $$

Question 10

Which of the following statements about passive transport is correct?

Accepted Answer

It moves substances down their concentration gradient.

Question 11

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion uses transport proteins to move molecules across the membrane.

Question 12

The sodium-potassium pump is an example of:

Accepted Answer

Active transport

Question 13

Which of the following best explains why ions such as Na	extsuperscript{+} and K	extsuperscript{+} require transport proteins to cross the plasma membrane?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the membrane.

Question 14

Which process involves the cell engulfing large particles or even whole cells?

Accepted Answer

Phagocytosis

Question 15

A cell uses receptor-mediated endocytosis to import cholesterol. What is the advantage of this process compared to pinocytosis?

Accepted Answer

It allows the cell to selectively import specific molecules.

Question 16

Which of the following equations best represents the relationship between water and solute concentration during osmosis?

Accepted Answer

$$ 	ext{Water moves from}~ 	ext{low solute}~ 	ext{to}~ 	ext{high solute concentration} $$

Question 17

Which of the following best describes cotransport in cell membranes?

Accepted Answer

The active transport of one solute indirectly drives the transport of another solute against its gradient.

Question 18

Which of the following is a real-world example of exocytosis?

Accepted Answer

A neuron releasing neurotransmitters into a synapse.

Question 19

Which of the following statements about membrane carbohydrates is correct?

Accepted Answer

They are most commonly covalently bonded to proteins, forming glycoproteins.

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