Q: Which equation correctly represents the calculation of membrane potential ($$V_m) $$using the Nernst equation for a monovalent ion?

$$V_m = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{outside}}}{[\text{ion}]_{\text{inside}}} \right)$$

Question 1

Which of the following best describes the fluid-mosaic model of the plasma membrane?

Accepted Answer

A dynamic structure where proteins and lipids move laterally within a flexible bilayer.

Question 2

A red blood cell is placed in a solution with an osmolarity of 400 mOsm/L, while the cell's internal osmolarity is 300 mOsm/L. Predict what will happen to the cell and explain why.

Accepted Answer

The cell will shrink because water will move out of the cell into the hypertonic solution.

Question 3

Which of the following molecules is most likely to diffuse directly through the lipid bilayer of a plasma membrane without the help of a transport protein?

Accepted Answer

O$$_2$$

Question 4

Which equation correctly represents the calculation of membrane potential ($$V_m) $$using the Nernst equation for a monovalent ion?

Accepted Answer

$$V_m = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 5

Which of the following best explains why the sodium-potassium pump is essential for nerve signal conduction?

Accepted Answer

It maintains the resting membrane potential by actively transporting Na$$^+$$ out and K$$^+$$ into the cell, using ATP.

Question 6

A cell is exposed to a hormone that is lipid-soluble. Which of the following best describes the pathway this hormone will take to elicit a response?

Accepted Answer

It diffuses through the plasma membrane and binds to an intracellular receptor, often affecting gene expression.

Question 7

Which of the following is an example of negative feedback in hormone regulation?

Accepted Answer

Elevated blood glucose stimulates insulin secretion, which lowers blood glucose and inhibits further insulin release.

Question 8

Which of the following best describes the role of second messengers such as cAMP in cell signaling?

Accepted Answer

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

Question 9

Which of the following best distinguishes between passive and active transport across cell membranes?

Accepted Answer

Passive transport moves substances down their concentration gradient without energy input; active transport moves substances against their gradient using energy, often from ATP.

Question 10

A neuron receives both excitatory and inhibitory signals. Which of the following best explains how the neuron decides whether to fire an action potential?

Accepted Answer

The neuron integrates all incoming signals at the axon hillock, and if the membrane potential reaches threshold, an action potential is generated.

Question 11

Which of the following best describes the difference between paracrine and endocrine signaling?

Accepted Answer

Paracrine signaling is local, affecting nearby cells; endocrine signaling involves hormones traveling long distances via the bloodstream.

Question 12

Which of the following is a correct sequence of events in the three stages of cell signaling?

Accepted Answer

Reception → Transduction → Response

Question 13

Which of the following best explains why the same signaling molecule can produce different responses in different cell types?

Accepted Answer

Different cells have different receptors or signal transduction pathways, leading to varied responses.

Question 14

Which of the following best describes the function of Schwann cells?

Accepted Answer

They form myelin sheaths around axons in the peripheral nervous system (PNS).

Question 15

Which of the following is true regarding the role of voltage-gated ion channels in action potential generation?

Accepted Answer

They open or close in response to changes in membrane potential, allowing rapid ion movement during action potentials.

Question 16

Which of the following best describes the process of exocytosis?

Accepted Answer

Vesicles fuse with the plasma membrane to release their contents outside the cell.

Question 17

Which of the following best explains the relationship between stimulus intensity and action potential frequency in sensory neurons?

Accepted Answer

A stronger stimulus increases the frequency of action potentials, not their amplitude.

Question 18

Which of the following is an example of antagonistic hormones and their role in homeostasis?

Accepted Answer

Insulin and glucagon regulate blood glucose levels in opposite directions.

Question 19

Which of the following best describes the role of astrocytes in the central nervous system?

Accepted Answer

They provide structural and metabolic support for neurons and help maintain the blood-brain barrier.

Question 20

Which of the following correctly matches a sensory receptor type with the stimulus it detects?

Accepted Answer

Mechanoreceptors – detect pressure and vibration

Bio 103 Exam 2 Study Guide: Membranes, Cell Communication, Endocrine System, Neurons, Nervous System, and Senses

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