Question 1

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

Accepted Answer

A mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.

Question 2

Which property of phospholipids is most responsible for the formation of the bilayer structure in cell membranes?

Accepted Answer

Their amphipathic nature, having both hydrophilic and hydrophobic regions.

Question 3

A researcher increases the proportion of unsaturated fatty acids in a cell membrane. What is the most likely effect on membrane fluidity at low temperatures?

Accepted Answer

Membrane fluidity will increase, preventing the membrane from solidifying as quickly.

Question 4

Which of the following best explains why cholesterol acts as a 'fluidity buffer' in animal cell membranes?

Accepted Answer

Cholesterol prevents the close packing of phospholipids at low temperatures and restrains movement at high temperatures.

Question 5

Which of the following is a function of integral membrane proteins?

Accepted Answer

They penetrate the hydrophobic interior of the lipid bilayer and can function in transport, signal transduction, or cell-cell recognition.

Question 6

Which of the following best describes the difference between channel proteins and carrier proteins?

Accepted Answer

Channel proteins provide a hydrophilic channel for molecules or ions to pass through, while carrier proteins bind to their passengers and change shape to shuttle them across.

Question 7

A cell is placed in a solution and begins to swell until it bursts. Which type of solution is the cell in, and what is the term for this process?

Accepted Answer

The cell is in a hypotonic solution; the process is lysis.

Question 8

Which of the following statements about passive transport is correct?

Accepted Answer

Passive transport involves the movement of substances down their concentration gradient without energy input.

Question 9

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

Accepted Answer

They are channel proteins that facilitate the passive movement of water molecules across the membrane.

Question 10

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

Accepted Answer

The cell will shrink because water leaves the cell to the area of higher solute concentration.

Question 11

Which of the following is an example of bulk transport across the plasma membrane?

Accepted Answer

Endocytosis of large particles by folding in of the cell membrane.

Question 12

Which of the following best explains why plant cells do not burst in hypotonic solutions, while animal cells do?

Accepted Answer

Plant cells have a cell wall that provides structural support and prevents excessive water uptake.

Question 13

Which of the following equations correctly represents the movement of water during osmosis?

Accepted Answer

$$ \Delta \Psi = \Psi_s + \Psi_p $$

Question 14

A cell membrane is composed of 40% phospholipids, 40% proteins, and 20% cholesterol. If the temperature drops significantly, which component will help maintain membrane fluidity?

Accepted Answer

Cholesterol, by preventing tight packing of phospholipids.

Question 15

Which of the following best describes facilitated diffusion?

Accepted Answer

Passive movement of molecules down their concentration gradient via specific transport proteins.

Question 16

Which of the following is a real-world example of cell-cell recognition mediated by membrane carbohydrates?

Accepted Answer

Sorting of cells into tissues and organs in an animal embryo.

Question 17

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral proteins are involved in transport, signal transduction, and cell-cell recognition.

Question 18

A solution has a higher concentration of solutes than the cytoplasm of a cell. What term describes this solution, and what is the expected movement of water?

Accepted Answer

Hypertonic; water moves out of the cell.

Question 19

Which of the following best describes the process of active transport?

Accepted Answer

Movement of molecules against their concentration gradient using energy, often in the form of ATP.

Question 20

Which of the following is a correct statement about the selective permeability of cell membranes?

Accepted Answer

The membrane allows some substances to cross more easily than others due to its structure.

Membrane Structure and Function: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard