Question 1

Which of the following best describes the function of the cell membrane?

Accepted Answer

It regulates what enters and leaves the cell, acting as a selective barrier.

Question 2

A scientist is studying a cell that has a high concentration of sodium ions outside the cell and a high concentration of potassium ions inside the cell. Which of the following best explains this distribution?

Accepted Answer

Potassium ions are actively transported into the cell, while sodium ions are actively transported out.

Question 3

Which of the following statements about the phospholipid bilayer is correct?

Accepted Answer

The hydrophilic heads face both the extracellular and intracellular fluids, while the hydrophobic tails face inward.

Question 4

Integral (intrinsic) proteins differ from peripheral (extrinsic) proteins in that:

Accepted Answer

Integral proteins are embedded within the membrane and cannot be easily separated without damaging the membrane.

Question 5

A cell lining the small intestine has numerous microvilli. What is the primary function of these structures?

Accepted Answer

To increase the surface area for absorption of nutrients.

Question 6

Tight junctions between epithelial cells in the digestive tract serve to:

Accepted Answer

Prevent the passage of enzymes, acids, and wastes between cells.

Question 7

Which of the following best explains why the cell membrane is described as a 'fluid mosaic'?

Accepted Answer

It is made up of various proteins and lipids that can move laterally within the bilayer.

Question 8

If a cell is placed in a hypotonic solution, what will most likely happen to the cell?

Accepted Answer

Water will move into the cell, causing it to swell.

Question 9

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

Accepted Answer

It increases membrane fluidity and stability.

Question 10

A researcher observes that a certain protein is only loosely attached to the inner surface of the plasma membrane and can be easily separated from it. This protein is most likely:

Accepted Answer

A peripheral protein

Question 11

Which of the following best describes the difference between cytoplasm and cytosol?

Accepted Answer

Cytoplasm is the material between the plasma membrane and the nucleus, including organelles; cytosol is the fluid portion in which organelles are suspended.

Question 12

Which of the following ions is found in higher concentration in the extracellular fluid (ECF) compared to the intracellular fluid (ICF)?

Accepted Answer

Sodium ($Na^+$)

Question 13

A cell membrane is selectively permeable. Which of the following substances is most likely to diffuse directly through the phospholipid bilayer without the help of a protein channel?

Accepted Answer

A small nonpolar molecule like oxygen ($O_2$)

Question 14

Which of the following best explains why the inside of the cell membrane is negatively charged compared to the outside?

Accepted Answer

The distribution of ions and proteins creates a charge difference across the membrane.

Question 15

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

Accepted Answer

Forming a rigid barrier to prevent all movement

Question 16

A cell is placed in a solution with 0.5% glucose, which is lower than the concentration inside the cell. What type of solution is this, and what will happen to the cell?

Accepted Answer

Hypotonic; the cell will swell as water enters.

Question 17

Which of the following best describes the role of tight junctions in epithelial tissue?

Accepted Answer

They prevent the passage of water and solutes between cells.

Question 18

Which of the following is a correct statement about the structure of the cell membrane?

Accepted Answer

The hydrophobic tails of phospholipids face each other in the interior of the membrane.

Question 19

Which of the following best explains why cells lining the digestive tract have many microvilli?

Accepted Answer

To increase the surface area for absorption of nutrients.

Cell Structure and Function: Foundations of Cytology

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