Question 1

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

Accepted Answer

A double layer of phospholipids with proteins and cholesterol embedded, allowing lateral movement

Question 2

A red blood cell is placed in a hypotonic solution. Which process will occur, and what is the likely outcome for the cell?

Accepted Answer

Osmosis; water will enter the cell, causing it to swell and possibly lyse

Question 3

Which of the following is a function of cholesterol in the plasma membrane?

Accepted Answer

Increases membrane stability by reducing fluidity at high temperatures

Question 4

Integral proteins in the plasma membrane are primarily responsible for which of the following?

Accepted Answer

Facilitating the transport of substances across the membrane

Question 5

A patient is diagnosed with a genetic disorder that affects the glycoalyx of their cells. Which of the following symptoms is most likely to occur as a result?

Accepted Answer

Impaired ability to recognize self from non-self cells, leading to autoimmune reactions

Question 6

Which of the following best explains why water can cross the plasma membrane via osmosis?

Accepted Answer

Water moves through specific channels called aquaporins and also diffuses through the lipid bilayer

Question 7

Which equation best represents the net movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$$J_v = L_p (\Delta P - \sigma \Delta \pi)$$

Question 8

A cell is actively transporting sodium ions ($$Na^+) $$out of the cell against their concentration gradient. Which of the following statements is true regarding this process?

Accepted Answer

It requires carrier proteins and the hydrolysis of ATP

Question 9

Which of the following best describes the difference between phagocytosis and pinocytosis?

Accepted Answer

Phagocytosis engulfs large particles, while pinocytosis engulfs extracellular fluid and dissolved solutes

Question 10

A neuron releases neurotransmitters into the synaptic cleft via exocytosis. Which of the following steps is essential for this process?

Accepted Answer

Fusion of a secretory vesicle with the plasma membrane

Question 11

Which of the following organelles is responsible for synthesizing membrane-bound and secreted proteins?

Accepted Answer

Rough endoplasmic reticulum

Question 12

A cell is observed to have an abundance of smooth endoplasmic reticulum. Which function is this cell most likely specialized for?

Accepted Answer

Lipid metabolism and detoxification of drugs

Question 13

Which of the following best describes the role of the Golgi apparatus in the cell?

Accepted Answer

Modifies, concentrates, and packages proteins and lipids from the rough ER

Question 14

Which of the following statements about mitochondria is correct?

Accepted Answer

They provide most of the cell's ATP via aerobic cellular respiration

Question 15

A scientist isolates a cell and finds that it contains both free and membrane-bound ribosomes. What can be inferred about the cell's protein synthesis?

Accepted Answer

It synthesizes proteins for use in the cytosol and for export or incorporation into membranes

Question 16

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

Accepted Answer

They allow some molecules to pass through easily while restricting others

Question 17

A cell is placed in a solution where the concentration of solutes is higher outside the cell than inside. What will happen to the cell, and which process is responsible?

Accepted Answer

The cell will shrink due to osmosis

Question 18

Which of the following is a characteristic of passive transport across the plasma membrane?

Accepted Answer

Moves substances down their concentration gradient

Question 19

Which of the following best describes the function of peripheral proteins in the plasma membrane?

Accepted Answer

They are loosely attached and function as enzymes or in cell shape and movement

Cells: The Living Units – Structure and Function of the Plasma Membrane and Organelles

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