Q: Which equation best represents the calculation of osmolarity ($$Osm) of a $$solution?

$$Osm = \sum_{i} C_{i} \times n_{i}$$, where $$C_{i} is $$the molar concentration and $$n_{i} is $$the number of particles per molecule

Question 1

Which of the following best describes the difference between osmotic equilibrium and chemical disequilibrium in the human body?

Accepted Answer

Osmotic equilibrium means water concentrations are equal across compartments, while chemical disequilibrium means solute concentrations differ across compartments.

Question 2

A patient receives an intravenous (IV) solution that is hypertonic compared to their plasma. What is the most likely effect on their red blood cells?

Accepted Answer

Water will leave the cells, causing them to shrink (crenate).

Question 3

Which equation correctly represents the Nernst equation for calculating the equilibrium potential ($$E_{ion}) of an $$ion across a membrane?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 4

Which of the following transport processes requires direct input of cellular energy (ATP) to move substances against their concentration gradient?

Accepted Answer

Primary active transport

Question 5

The sodium-potassium pump ($$Na^+/K^+$$ ATPase) moves ions across the plasma membrane. For each cycle, how many sodium and potassium ions are transported, and in which direction?

Accepted Answer

3 $$Na^+$$ out, 2 $$K^+ in$$

Question 6

Which of the following best explains why the resting membrane potential of a neuron is typically negative?

Accepted Answer

The membrane is more permeable to $$K^+$$ ions, which leak out, leaving behind negatively charged proteins.

Question 7

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

Accepted Answer

Glucose uptake via the sodium-glucose cotransporter (SGLT)

Question 8

Which statement about facilitated diffusion is correct?

Accepted Answer

It requires a carrier protein and moves substances down their concentration gradient without energy input.

Question 9

Which of the following is NOT a characteristic of G protein-coupled receptors (GPCRs)?

Accepted Answer

They directly phosphorylate target proteins.

Question 10

A cell is exposed to a novel signaling molecule that binds to a receptor-enzyme. What is the most likely immediate cellular response?

Accepted Answer

Activation of an intracellular enzyme via phosphorylation

Question 11

Which of the following best describes the role of second messengers in signal transduction?

Accepted Answer

They relay and amplify signals from membrane receptors to target proteins inside the cell.

Question 12

Which equation best represents the calculation of osmolarity ($$Osm) of a $$solution?

Accepted Answer

$$Osm = \sum_{i} C_{i} 	imes n_{i}$$, where $$C_{i} is $$the molar concentration and $$n_{i} is $$the number of particles per molecule

Question 13

Which of the following is an example of paracrine signaling?

Accepted Answer

A cell releases a growth factor that acts on neighboring cells.

Question 14

Which statement about homeostasis is correct?

Accepted Answer

Homeostasis maintains dynamic stability, not absolute equilibrium, in the body.

Question 15

Which of the following is a feature of antagonistic control in homeostatic systems?

Accepted Answer

Two systems exert opposite effects on the same variable.

Question 16

Which of the following is a correct example of upregulation of a receptor?

Accepted Answer

A cell increases the number of receptors on its surface in response to low ligand concentration.

Question 17

Which of the following is a step in the general signaling pathway?

Accepted Answer

Signal molecule binds to receptor

Question 18

Which of the following best describes the function of gap junctions in cell communication?

Accepted Answer

They allow direct passage of ions and small molecules between adjacent cells.

Question 19

Which of the following is a plausible consequence of saturation of a membrane transporter?

Accepted Answer

Transport rate reaches a maximum and cannot increase further even if substrate concentration increases.

Homeostasis, Membrane Transport, and Cell Communication: Study Notes for Anatomy & Physiology

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