Q: If a solution contains 0.2 mol/L NaCl, what is its osmolarity in mOsm/L? (Assume complete dissociation.)

$$0.2 \times 2 = 0.4$$ mol/L $$= 400$$ mOsm/L

Q: Which equation correctly calculates the osmolarity of a solution containing 0.1 mol/L CaCl$$_2$$? (Assume complete dissociation.)

$$0.1 \times 3 = 0.3$$ mol/L $$= 300$$ mOsm/L

Q: A solution contains 0.15 mol/L glucose and 0.15 mol/L NaCl. What is the total osmolarity of the solution?

$$0.15 \times 1 + 0.15 \times 2 = 0.15 + 0.30 = 0.45$$ mol/L $$= 450$$ mOsm/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 plasma membrane is described by the 'fluid mosaic model.' Which component is primarily responsible for the membrane's hydrophobic barrier?

Accepted Answer

Phospholipids

Question 3

Which type of cell junction allows direct and rapid communication between the cytoplasm of neighboring cells, such as in cardiac muscle?

Accepted Answer

Gap junctions

Question 4

A researcher observes that water moves freely between the intracellular fluid (ICF) and extracellular fluid (ECF) until the concentration of water is equal in both compartments. This phenomenon is best described as:

Accepted Answer

Osmotic equilibrium

Question 5

If a solution contains 0.2 mol/L NaCl, what is its osmolarity in mOsm/L? (Assume complete dissociation.)

Accepted Answer

$$0.2 	imes 2 = 0.4$$ mol/L $$= 400$$ mOsm/L

Question 6

Which of the following best explains why the resting membrane potential of a typical neuron is closer to the equilibrium potential of K$$^+$$ than Na$$^+$$?

Accepted Answer

There are more K$$^+$$ channels than Na$$^+$$ channels in the membrane.

Question 7

Which equation correctly calculates the osmolarity of a solution containing 0.1 mol/L CaCl$$_2$$? (Assume complete dissociation.)

Accepted Answer

$$0.1 	imes 3 = 0.3$$ mol/L $$= 300$$ mOsm/L

Question 8

A cell is placed in a solution that is hypertonic to its cytoplasm. What will happen to the cell?

Accepted Answer

It will shrink as water leaves the cell.

Question 9

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses membrane proteins to transport lipophobic molecules down their concentration gradient.

Question 10

According to Fick's law, which factor does NOT increase the rate of diffusion across a biological membrane?

Accepted Answer

Decreasing the membrane surface area

Question 11

Which of the following best describes the role of the Na$$^+/K$^+$$ ATPase in maintaining the resting membrane potential?

Accepted Answer

It pumps 3 Na$$^+$$ out and 2 K$$^+ in$$, creating a net negative charge inside the cell.

Question 12

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

Accepted Answer

SGLT transporter (sodium-glucose linked transporter)

Question 13

A solution contains 0.15 mol/L glucose and 0.15 mol/L NaCl. What is the total osmolarity of the solution?

Accepted Answer

$$0.15 	imes 1 + 0.15 	imes 2 = 0.15 + 0.30 = 0.45$$ mol/L $$= 450$$ mOsm/L

Question 14

Which of the following statements about membrane permeability is correct?

Accepted Answer

A membrane permeable to glucose allows glucose to pass through.

Question 15

If the equilibrium potential for ion A is +20 mV and for ion B is -40 mV, and the cell's resting membrane potential is -20 mV, which ion does the cell membrane have greater permeability to?

Accepted Answer

Ion B

Question 16

Which process is responsible for moving large molecules such as proteins into the cell, and requires ATP?

Accepted Answer

Endocytosis

Question 17

Which of the following best describes the effect of increasing membrane permeability to Na$$^+ on $$the cell's membrane potential?

Accepted Answer

The membrane potential becomes more positive (depolarization).

Question 18

Which property of protein-mediated transport describes the phenomenon where all transporters are occupied and the rate of transport cannot increase further?

Accepted Answer

Saturation

Question 19

Which of the following is NOT a function of the plasma membrane?

Accepted Answer

Synthesis of DNA

Cell Plasma Membrane and Cell Junctions: Structure and Function

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