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 $$0.9\,	ext{M}$$ NaCl (isotonic to the cell). What will happen to the cell?

Accepted Answer

There will be no net movement of water, and the cell will remain the same size.

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

The sodium-potassium pump is essential for maintaining the resting membrane potential in neurons. Which of the following best describes its action?

Accepted Answer

It moves 3 Na$$^+$$ ions out of the cell and 2 K$$^+$$ ions in, using ATP.

Question 5

Which of the following best explains why a hormone like epinephrine can trigger different responses in different cell types?

Accepted Answer

Different cells have different receptors or signal transduction pathways.

Question 6

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

Accepted Answer

High blood glucose stimulates insulin release, which lowers blood glucose, reducing further insulin release.

Question 7

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

Accepted Answer

They relay signals from membrane receptors to target molecules inside the cell, amplifying the signal.

Question 8

A neuron receives both excitatory and inhibitory signals. What determines whether it will fire an action potential?

Accepted Answer

Whether the sum of graded potentials at the axon hillock reaches the threshold potential.

Question 9

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

Accepted Answer

Paracrine signaling is local, affecting nearby cells; endocrine signaling is long-distance, affecting distant cells via the bloodstream.

Question 10

Which of the following is a function of astrocytes in the central nervous system?

Accepted Answer

Providing metabolic support and maintaining the blood-brain barrier.

Question 11

A patient is given a drug that blocks voltage-gated Na$$^+$$ channels in neurons. What is the most likely effect on nerve signal conduction?

Accepted Answer

Action potentials will not be generated, preventing nerve signal transmission.

Question 12

Which of the following best describes the process of exocytosis?

Accepted Answer

The fusion of vesicles with the plasma membrane to release contents outside the cell.

Question 13

Which of the following best explains why lipid-soluble hormones can bind to intracellular receptors, while water-soluble hormones cannot?

Accepted Answer

Lipid-soluble hormones can diffuse through the plasma membrane, but water-soluble hormones cannot.

Question 14

Which of the following is the correct sequence of events in a typical signal transduction pathway?

Accepted Answer

Reception → Transduction → Response

Question 15

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

Accepted Answer

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

Question 16

A cell is placed in a hypertonic solution. Predict the net movement of water and the effect on the cell.

Accepted Answer

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

Question 17

Which of the following best describes the function of ligand-gated ion channels in neurons?

Accepted Answer

They open when a specific chemical messenger binds, allowing ions to flow and generate graded potentials.

Question 18

Which of the following is an example of a tropic hormone?

Accepted Answer

Thyroid-stimulating hormone (TSH), which stimulates the thyroid gland.

Question 19

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

Accepted Answer

A stronger stimulus increases the frequency of action potentials.

Question 20

Which of the following best describes the role of the sympathetic division of the autonomic nervous system?

Accepted Answer

It prepares the body for fight-or-flight responses, such as increasing heart rate and inhibiting digestion.

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

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