Q: Which equation correctly calculates the osmolarity of a solution containing 0.2 mol/L NaCl?

$$\text{Osmolarity} = 0.2 \, \text{mol/L} \times 2 = 0.4 \, \text{Osm/L}$$

Q: A solution containing 0.15 mol/L glucose and 0.15 mol/L NaCl is compared to a normal cell (300 mOsm/L). What is the osmolarity of the solution?

$$0.15 \times 1 + 0.15 \times 2 = 0.15 + 0.30 = 0.45 \, \text{Osm/L} = 450 \, \text{mOsm/L}$$

Q: Which statement best explains why the plasma membrane is more permeable to K\textsuperscript{+} than Na\textsuperscript{+} at rest?

There are more K\textsuperscript{+} leak channels than Na\textsuperscript{+} channels in the membrane.

Q: Which equation represents Fick's Law for diffusion rate ($$J) $$across a membrane?

$$J = D \times A \times \frac{\Delta C}{d}$$

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

Na\textsuperscript{+}/K\textsuperscript{+} ATPase pump

Question 1

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

Accepted Answer

It separates the intracellular fluid (ICF) from the extracellular fluid (ECF), acting as a selective barrier.

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 communication between the cytoplasm of adjacent cells?

Accepted Answer

Gap junctions

Question 4

A cardiac muscle cell relies on which type of cell junction to synchronize contraction with its neighbors?

Accepted Answer

Desmosomes and gap junctions

Question 5

Which equation correctly calculates the osmolarity of a solution containing 0.2 mol/L NaCl?

Accepted Answer

$$	ext{Osmolarity} = 0.2 \, 	ext{mol/L} 	imes 2 = 0.4 \, 	ext{Osm/L}$$

Question 6

A solution containing 0.15 mol/L glucose and 0.15 mol/L NaCl is compared to a normal cell (300 mOsm/L). What is the osmolarity of the solution?

Accepted Answer

$$0.15 	imes 1 + 0.15 	imes 2 = 0.15 + 0.30 = 0.45 \, 	ext{Osm/L} = 450 \, 	ext{mOsm/L}$$

Question 7

Which statement best explains why the plasma membrane is more permeable to K	extsuperscript{+} than Na	extsuperscript{+} at rest?

Accepted Answer

There are more K	extsuperscript{+} leak channels than Na	extsuperscript{+} channels in the membrane.

Question 8

If a cell is placed in a solution that is hypertonic to its cytoplasm, what will happen to the cell?

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 9

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses membrane proteins to move 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 membrane permeability

Question 11

Which equation represents Fick's Law for diffusion rate ($$J) $$across a membrane?

Accepted Answer

$$J = D 	imes A 	imes \frac{\Delta C}{d}$$

Question 12

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

Accepted Answer

Na	extsuperscript{+}/K	extsuperscript{+} ATPase pump

Question 13

The SGLT transporter moves glucose into the cell by coupling its transport to Na	extsuperscript{+} movement. This is an example of:

Accepted Answer

Secondary active transport

Question 14

Which of the following best describes the process of exocytosis?

Accepted Answer

Movement of large molecules out of the cell using vesicles and ATP

Question 15

A cell's resting membrane potential is -70 mV. The equilibrium potential for K	extsuperscript{+} is -90 mV and for Na	extsuperscript{+} is +60 mV. Which ion 'pulls harder' on the membrane potential?

Accepted Answer

K	extsuperscript{+}, because the resting potential is closer to its equilibrium potential

Question 16

If the membrane permeability to Na	extsuperscript{+} suddenly increases, what will happen to the cell's membrane potential?

Accepted Answer

It will become more positive (depolarize)

Question 17

Which of the following is NOT a characteristic of protein-mediated transport?

Accepted Answer

Unlimited transport rate regardless of substrate concentration

Question 18

A cell is placed in a solution containing 200 mOsm/L non-penetrating solutes. What is the tonicity of the solution compared to the cell (300 mOsm/L non-penetrating solutes)?

Accepted Answer

Hypotonic

Question 19

Which of the following best describes electrical disequilibrium in cells?

Accepted Answer

Unequal distribution of cations and anions between the ICF and ECF

Cell Plasma Membrane and Cell Junctions: Structure and Function

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