Q: Which equation correctly expresses the calculation of solution concentration in terms of molarity?

$$M = \frac{\text{amount of solute (mol)}}{\text{volume of solution (L)}}$$

Question 1

Which of the following best describes the difference between osmolarity and tonicity in relation to cell membrane transport?

Accepted Answer

Osmolarity is a measure of the total concentration of solutes (permeant and impermeant), while tonicity refers specifically to the concentration of impermeant solutes that affect cell volume.

Question 2

A red blood cell is placed in a solution with a total solute concentration of 400 mOsm, all of which are impermeant to the cell membrane. What will happen to the cell?

Accepted Answer

The cell will shrink because the solution is hypertonic.

Question 3

Which equation correctly expresses the calculation of solution concentration in terms of molarity?

Accepted Answer

$$M = \frac{	ext{amount of solute (mol)}}{	ext{volume of solution (L)}}$$

Question 4

Which of the following factors will NOT increase the rate of simple diffusion across a cell membrane?

Accepted Answer

Increasing the thickness of the membrane.

Question 5

A patient is given an intravenous solution of 0.45% saline (half-normal saline). Which statement best describes the effect on their red blood cells?

Accepted Answer

The solution is hypotonic, causing the cells to swell.

Question 6

Which of the following best describes the function of the Na$$^+-K$^+-$$ATPase pump?

Accepted Answer

It uses ATP to move 3 Na$$^+$$ out of the cell and 2 K$$^+$$ into the cell against their concentration gradients.

Question 7

Which of the following is a correct example of secondary active transport?

Accepted Answer

Movement of glucose into a cell via the SGLT symporter, using the Na$$^+$$ gradient established by the Na$$^+-K$^+-$$ATPase.

Question 8

Which of the following statements about facilitated diffusion is TRUE?

Accepted Answer

It uses carrier proteins to move molecules down their concentration gradient without using ATP.

Question 9

If a cell is placed in a solution with a lower concentration of impermeant solutes than its cytosol, what type of solution is this and what will happen to the cell?

Accepted Answer

The solution is hypotonic; the cell will swell.

Question 10

Which of the following best explains why water moves across cell membranes during osmosis?

Accepted Answer

Water moves from areas of high water concentration to areas of low water concentration through aquaporins or directly across the membrane.

Question 11

Which formula correctly expresses osmolarity ($$Osm) of a $$solution?

Accepted Answer

$$Osm = \frac{	ext{osmoles of solute}}{	ext{liters of solution}}$$

Question 12

A cell is placed in a solution containing 300 mOsm of permeant solutes and 200 mOsm of impermeant solutes. What is the tonicity of the solution?

Accepted Answer

Hypotonic

Question 13

Which of the following is a property of carrier-mediated transport that distinguishes it from simple diffusion?

Accepted Answer

Carrier-mediated transport can exhibit saturation when all carriers are occupied.

Question 14

Which of the following is TRUE regarding the distribution of ions in body fluid compartments?

Accepted Answer

Intracellular fluid has a higher concentration of K$$^+$$ and a lower concentration of Na$$^+$$ compared to extracellular fluid.

Question 15

Which process is responsible for the release of neurotransmitters from neurons?

Accepted Answer

Exocytosis

Question 16

Which of the following is an example of antiport (countertransport) in secondary active transport?

Accepted Answer

Na$$^+-H$^+$$ exchanger (NHE)

Question 17

Which of the following statements about aquaporins is correct?

Accepted Answer

Aquaporins are channels that allow rapid movement of water across cell membranes.

Question 18

A patient with diabetes mellitus has reduced GLUT4 transporter activity. What is the most likely consequence for glucose transport into muscle and adipose cells?

Accepted Answer

Glucose transport will decrease, leading to elevated blood glucose.

Question 19

Which of the following best describes the effect of increasing the number of open ion channels in a cell membrane?

Accepted Answer

It increases the membrane's permeability to that ion, allowing more rapid movement.

Cell Membrane Transport and Body Fluid Compartments: Study Notes

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