Q: Which equation best describes the movement of water during osmosis?

$$\text{Water moves from a region of low solute concentration to high solute concentration}$$

Question 1

Which of the following best describes the amphipathic nature of phospholipids in the plasma membrane?

Accepted Answer

Phospholipids have both hydrophobic tails and hydrophilic heads, allowing them to form a bilayer with hydrophilic heads facing the aqueous environment and hydrophobic tails facing each other.

Question 2

A red blood cell is placed in a solution with a higher concentration of solutes than inside the cell. What will most likely happen to the cell?

Accepted Answer

It will lose water and shrivel, a process known as crenation.

Question 3

Which of the following molecules can most easily cross the plasma membrane without the aid of a transport protein?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 4

What is the primary function of cholesterol in the plasma membrane?

Accepted Answer

It buffers membrane fluidity, preventing solidification at low temperatures and restraining movement at high temperatures.

Question 5

Which type of transport requires both energy input and a transport protein to move molecules against their concentration gradient?

Accepted Answer

Active transport

Question 6

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

Accepted Answer

The cell will gain water, become turgid, and maintain its healthy state.

Question 7

Which of the following best explains why membranes rich in unsaturated fatty acids remain more fluid at lower temperatures?

Accepted Answer

Unsaturated fatty acids have kinks in their tails, preventing tight packing and solidification.

Question 8

Which of the following is a function of membrane proteins?

Accepted Answer

They facilitate transport, act as enzymes, receive signals, and help with cell recognition.

Question 9

The sodium-potassium pump moves ions across the plasma membrane. Which equation best represents the stoichiometry of this pump?

Accepted Answer

$$3\ \mathrm{Na^+}$$ out, $$2\ \mathrm{K^+} in$

Question 10

Which process allows large molecules such as proteins to exit the cell?

Accepted Answer

Exocytosis

Question 11

A cell uses a cotransporter to move sucrose into its cytoplasm, coupled with the movement of $$\mathrm{H^+}$$ ions down their concentration gradient. What type of transport is this?

Accepted Answer

Active transport

Question 12

Which of the following statements about selective permeability is correct?

Accepted Answer

Hydrophobic molecules cross the membrane more easily than hydrophilic molecules.

Question 13

What is the main difference between channel proteins and carrier proteins in facilitated diffusion?

Accepted Answer

Channel proteins provide a hydrophilic passageway, while carrier proteins undergo shape changes to transport molecules.

Question 14

Which equation best describes the movement of water during osmosis?

Accepted Answer

$$	ext{Water moves from a region of low solute concentration to high solute concentration}$$

Question 15

Which of the following is true about the fluid mosaic model of the plasma membrane?

Accepted Answer

The membrane consists of a mosaic of proteins bobbing in a fluid bilayer of phospholipids.

Question 16

Which of the following best describes receptor-mediated endocytosis?

Accepted Answer

It involves the selective uptake of specific molecules bound to receptors on the cell surface.

Question 17

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

There will be no net movement of water; the cell remains stable.

Question 18

Which of the following is an example of bulk transport?

Accepted Answer

Exocytosis of neurotransmitters

Question 19

What is the role of electrogenic pumps in cells?

Accepted Answer

They generate voltage across membranes by moving ions, creating an electrochemical gradient.

Question 20

Which of the following best describes the movement of ions across a membrane according to the electrochemical gradient?

Accepted Answer

Ions move according to both their concentration gradient and the membrane potential.

Membrane Structure and Function: Study Notes

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