Question 1

Which of the following best describes the difference between a hormone and a paracrine chemical messenger?

Accepted Answer

A hormone is released into the bloodstream to affect distant cells, while a paracrine messenger acts locally on nearby cells.

Question 2

Steroid hormones typically act slower but have more prolonged responses than protein and biogenic amine hormones. Which of the following best explains this phenomenon?

Accepted Answer

Steroid hormones bind to intracellular receptors and alter gene transcription, leading to slower but longer-lasting effects.

Question 3

Which of the following is a water-soluble hormone that typically binds to cell membrane receptors?

Accepted Answer

Insulin

Question 4

A cell responds to a hormone by increasing the production of cyclic adenosine monophosphate (cAMP). Which enzyme is directly responsible for this increase?

Accepted Answer

Adenylate cyclase (AC)

Question 5

Which of the following best describes the process of amplification in hormone signaling?

Accepted Answer

A single hormone molecule triggers the activation of many intracellular molecules, resulting in a large cellular response.

Question 6

Which of the following is a correct sequence for the G-protein coupled receptor (GPCR) pathway involving phospholipase C?

Accepted Answer

Hormone binds GPCR → G-protein activates phospholipase C → IP3 and DAG produced → protein kinase C activated

Question 7

Which of the following is NOT a second messenger in signal transduction?

Accepted Answer

Protein kinase A (PKA)

Question 8

A patient has a mutation that prevents the formation of inositol triphosphate ($$IP_3) in $$response to hormone stimulation. Which cellular process would be most directly affected?

Accepted Answer

Release of calcium ions from the endoplasmic reticulum

Question 9

Which of the following statements about receptor specificity is correct?

Accepted Answer

Different cells may express different receptors for the same hormone, leading to varied responses.

Question 10

Which of the following is a plausible effect of a hormone acting as a first messenger?

Accepted Answer

It binds to a receptor and triggers the production of a second messenger inside the cell.

Question 11

Which of the following best explains why steroid hormones can cross the plasma membrane while peptide hormones cannot?

Accepted Answer

Steroid hormones are non-polar and lipid-soluble, allowing them to diffuse through the lipid bilayer.

Question 12

A researcher is studying the effects of a new drug that blocks protein kinase A (PKA) activity. Which hormone signaling pathway would be most directly affected?

Accepted Answer

Pathway involving adenylate cyclase and $$cAMP$$

Question 13

Which of the following is a correct description of a ligand?

Accepted Answer

A ligand is a molecule that binds specifically to a receptor to initiate a cellular response.

Question 14

Which of the following would most likely result from a mutation that prevents the activation of G-protein coupled receptors (GPCRs)?

Accepted Answer

Impaired signal transduction for hormones that use second messenger systems

Question 15

A cell is exposed to a hormone that increases the activity of phospholipase C (PLC). Which two second messengers are produced as a result?

Accepted Answer

Diacylglycerol (DAG) and inositol triphosphate ($$IP_3)$$

Question 16

Which of the following is a direct effect of increased concentrations of circulating hormones?

Accepted Answer

Increased likelihood of receptor saturation and cellular response

Question 17

Which of the following best describes the role of protein kinase C (PKC) in signal transduction?

Accepted Answer

PKC is activated by DAG and phosphorylates target proteins in the cytoplasm.

Question 18

A cell expresses a receptor that, when activated, increases the production of $$cAMP. $$Which type of receptor is most likely involved?

Accepted Answer

G-protein coupled receptor (GPCR)

Question 19

Which of the following is a plausible consequence of a cell lacking hormone response elements (HREs) in its DNA?

Accepted Answer

The cell cannot respond to steroid hormones by altering gene transcription.

Chemical Messengers and Signal Transduction in Anatomy & Physiology

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