Question 1

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

Accepted Answer

A dynamic structure where proteins float in or on a fluid phospholipid bilayer.

Question 2

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer without the help of a transport protein?

Accepted Answer

Oxygen ($$O_2)$$

Question 3

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

Accepted Answer

It will swell and possibly burst as water enters the cell.

Question 4

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses transport proteins to move substances down their concentration gradient.

Question 5

The sodium-potassium pump ($$Na^+/K^+$$ pump) is an example of:

Accepted Answer

Active transport

Question 6

Which of the following best explains why cell membranes are described as 'selectively permeable'?

Accepted Answer

They allow some substances to cross more easily than others.

Question 7

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will lose water and undergo plasmolysis.

Question 8

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Cell-cell recognition

Question 9

Which process requires the expenditure of energy by the cell?

Accepted Answer

Active transport of $$Na^+$$ out of the cell

Question 10

A cell uses exocytosis to:

Accepted Answer

Release large molecules, such as hormones, to the outside

Question 11

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

It helps maintain membrane fluidity at different temperatures.

Question 12

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

Accepted Answer

There will be no net movement of water.

Question 13

Which of the following is true about the movement of ions across a membrane?

Accepted Answer

Ions require specific transport proteins to cross the membrane.

Question 14

Which of the following best describes the process of osmosis?

Accepted Answer

The movement of water molecules from low to high solute concentration.

Question 15

A cell with a membrane potential of $$-70\ \mathrm{mV} is $$said to have:

Accepted Answer

A negative charge inside relative to outside.

Question 16

Which of the following is an example of cotransport?

Accepted Answer

The movement of $$Na^+$$ and glucose into a cell together, using the $$Na^+$$ gradient.

Question 17

Which of the following best explains why phospholipids form bilayers in water?

Accepted Answer

Their hydrophilic heads interact with water, while hydrophobic tails avoid water.

Question 18

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

Accepted Answer

Storing genetic information

Question 19

During phagocytosis, a cell:

Accepted Answer

Engulfs large particles or cells by wrapping the plasma membrane around them.

Question 20

Which of the following scenarios best illustrates the concept of tonicity?

Accepted Answer

A freshwater protozoan living in a pond expels excess water using a contractile vacuole.

Membrane Structure and Function: Study Notes for General Biology

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