Q: A cell is placed in a solution containing 1 M glucose and 1 M NaCl. What is the total osmolarity of the solution?

$$1 \times 1 + 1 \times 2 = 3$$ Osm/L

Question 1

Which of the following best describes the primary function of the plasma membrane in a human cell?

Accepted Answer

It separates the intracellular environment from the extracellular fluid.

Question 2

The fluid mosaic model of the plasma membrane includes which of the following components?

Accepted Answer

Phospholipids, proteins, carbohydrates, and cholesterol

Question 3

Which type of cell junction allows direct and rapid cell-to-cell communication between the cytosol of neighboring cells?

Accepted Answer

Gap junctions

Question 4

What is the main role of tight junctions in epithelial tissues?

Accepted Answer

To block the movement of material between cells

Question 5

Desmosomes are best described as:

Accepted Answer

Cell-to-cell anchoring junctions that provide structural support

Question 6

Which of the following is a correct statement about the movement of water in osmosis?

Accepted Answer

Water moves from areas of low solute concentration to areas of high solute concentration.

Question 7

Calculate the osmolarity of a 0.5 M NaCl solution. (Assume complete dissociation.)

Accepted Answer

$$0.5 	imes 2 = 1.0$$ Osm/L

Question 8

A cell is placed in a solution containing 1 M glucose and 1 M NaCl. What is the total osmolarity of the solution?

Accepted Answer

$$1 	imes 1 + 1 	imes 2 = 3$$ Osm/L

Question 9

Which of the following best describes a hypertonic solution?

Accepted Answer

A solution with a higher concentration of non-penetrating solutes than the cell

Question 10

If a red blood cell is placed in a hypotonic solution, what will happen to the cell?

Accepted Answer

It will swell as water moves into the cell.

Question 11

Which factor does NOT directly affect the rate of diffusion across a biological membrane according to Fick's law?

Accepted Answer

Number of mitochondria

Question 12

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

It requires a membrane protein to transport lipophobic molecules.

Question 13

Which of the following is an example of primary active transport?

Accepted Answer

Na*/K* ATPase pump

Question 14

The SGLT transporter is an example of secondary active transport because:

Accepted Answer

It uses the Na* gradient established by ATP hydrolysis to transport glucose.

Question 15

Which property is shared by all types of protein-mediated transport?

Accepted Answer

Specificity, competition, and saturation

Question 16

What is the effect on the cell membrane potential if the membrane becomes more permeable to Na*?

Accepted Answer

The membrane potential becomes more positive (depolarization).

Question 17

Given the equilibrium potentials: $$E_{K^+} = -90 mV$$, $$E_{Na^+} = +60 mV$$, and a cell resting membrane potential of $$-70 mV$$, which ion is the membrane more permeable to?

Accepted Answer

K*

Question 18

Which process is responsible for moving large molecules such as proteins into the cell?

Accepted Answer

Endocytosis

Question 19

A cell is placed in a solution with 0.3 M NaCl and 0.3 M urea. If urea is a penetrating solute and NaCl is non-penetrating, what is the tonicity of the solution relative to the cell?

Accepted Answer

Isotonic

Cell Plasma Membrane and Cell Junctions: Structure and Function

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