Q: Which equation correctly describes the half-life decay of a hormone in plasma after four half-lives?

$$C = C_0$ \times (\frac{1}{2})^4$

Question 1

Which of the following best explains why steroid hormones generally have longer-lasting effects than peptide hormones?

Accepted Answer

Steroid hormones are lipid-soluble, require carrier proteins for transport, and act via direct gene activation, resulting in slower onset but prolonged effects.

Question 2

A patient with liver failure is likely to experience which of the following regarding hormone activity?

Accepted Answer

Increased hormone half-life due to impaired hepatic degradation.

Question 3

Which of the following is TRUE regarding the mechanism of action for water-soluble hormones?

Accepted Answer

They bind to membrane-bound receptors and activate second messenger cascades such as cAMP.

Question 4

Arrange the following steps of the cAMP second messenger pathway in the correct order:
1. Adenylyl cyclase converts ATP to cAMP
2. Hormone binds to membrane receptor
3. cAMP activates protein kinase A
4. G-protein activates adenylyl cyclase

Accepted Answer

2 → 4 → 1 → 3

Question 5

Which of the following best describes a negative feedback loop in endocrine regulation?

Accepted Answer

A hormone inhibits its own upstream secretion to maintain homeostasis.

Question 6

A patient with chronic high insulin levels develops insulin resistance. Which cellular process is most likely responsible?

Accepted Answer

Down-regulation of insulin receptors, reducing cellular sensitivity.

Question 7

Which of the following is an example of a hormone interaction described as 'synergism'?

Accepted Answer

Glucagon and epinephrine together causing a greater increase in blood glucose than either alone.

Question 8

Which equation correctly describes the half-life decay of a hormone in plasma after four half-lives?

Accepted Answer

$$C = C_0$ 	imes (\frac{1}{2})^4$

Question 9

Which of the following best explains why only target cells respond to a specific hormone?

Accepted Answer

Only target cells have the specific receptor that matches the hormone's shape.

Question 10

Which of the following is a correct statement about the difference between neural and endocrine signaling?

Accepted Answer

Neural signaling is rapid and precisely targeted, while endocrine signaling is slower and affects many cells over a longer duration.

Question 11

Which of the following is a humoral stimulus for hormone release?

Accepted Answer

A rise in blood glucose triggering insulin secretion.

Question 12

A water-soluble hormone is most likely to:

Accepted Answer

Bind to a membrane receptor and activate a second messenger cascade.

Question 13

Which of the following best describes the permissive effect of hormones?

Accepted Answer

One hormone enables another hormone to exert its full effect.

Question 14

Which of the following is NOT a factor that determines the plasma concentration of a hormone?

Accepted Answer

Number of mitochondria in target cells.

Question 15

Which of the following best explains why amplification occurs in second messenger systems?

Accepted Answer

Each hormone-receptor complex activates multiple G proteins, leading to exponential signal amplification.

Question 16

Which of the following is TRUE regarding the hypothalamic-pituitary interface?

Accepted Answer

The hypothalamus releases tropic hormones into the hypophyseal portal system to regulate the anterior pituitary.

Question 17

Which of the following scenarios best illustrates positive feedback in endocrine regulation?

Accepted Answer

Oxytocin release during childbirth amplifies uterine contractions until delivery.

Question 18

Which of the following is a correct sequence for the gene activation mechanism of a lipid-soluble hormone?

Accepted Answer

Hormone diffuses into cell → binds intracellular receptor → hormone-receptor complex binds DNA → mRNA transcription.

Question 19

Which of the following best describes the effect of up-regulation of hormone receptors?

Accepted Answer

Cells increase the number of receptors in response to low hormone levels, enhancing sensitivity.

Fundamentals of Endocrine Signaling and Action

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