BIO105 | BIO105 Anatomy and Physiology 1 Exam
4 Version 1 | Questions with Correct Answers and
Expert Explanation for Each Question | Saint Paul’s
School of Nursing
1. Which of the following describes the primary mechanism by which most hormones
are regulated in the body?
A. Positive feedback loops
B. Direct enzymatic degradation
C. Neural stimulation only
D. Negative feedback loops
Correct Answer: D
Expert Explanation: Negative feedback is the most common regulatory mechanism
in the endocrine system. It functions by detecting a change in a physiological
parameter and initiating a response to reverse that change. For instance, when
blood glucose levels rise, insulin is released to lower them back to normal. Once the
set point is reached, the production of the hormone is inhibited. This process is
essential for maintaining homeostasis throughout the entire body.
2. Which hormone is synthesized by the hypothalamus but stored and released by the
posterior pituitary gland?
A. Growth Hormone (GH)
,B. Thyroid Stimulating Hormone (TSH)
C. Antidiuretic Hormone (ADH)
D. Adrenocorticotropic Hormone (ACTH)
Correct Answer: C
Expert Explanation: Antidiuretic hormone is produced by neuronal cell bodies
located in the hypothalamus. It is then transported down axons to the posterior
pituitary for storage and eventual release. Unlike the anterior pituitary, the
posterior pituitary does not produce its own hormones. ADH plays a critical role in
regulating water balance by acting on the kidneys. This demonstrates the close
integration between the nervous and endocrine systems.
3. Steroid hormones are derived from which of the following molecules?
A. Amino acids
B. Peptides
C. Nucleic acids
D. Cholesterol
Correct Answer: D
Expert Explanation: Steroid hormones are lipid-soluble molecules that are
synthesized from cholesterol. Because they are lipids, they can easily diffuse
,through the phospholipid bilayer of target cell membranes. Examples of these
hormones include cortisol, testosterone, and estrogen. Once inside the cell, they
typically bind to intracellular receptors to influence gene expression. Their chemical
structure allows them to have long-lasting effects compared to water-soluble
hormones.
4. Which second messenger is commonly used by water-soluble hormones to trigger a
cellular response?
A. Cyclic AMP (cAMP)
B. Adenosine triphosphate (ATP)
C. Acetylcholine
D. Sodium ions
Correct Answer: A
Expert Explanation: Water-soluble hormones cannot cross the cell membrane and
must bind to receptors on the cell surface. This binding activates a G protein, which
then stimulates the enzyme adenylate cyclase. Adenylate cyclase converts ATP into
cyclic AMP, which acts as the second messenger. cAMP then activates protein
kinases that trigger a cascade of enzymatic reactions within the cell. This
amplification process allows a small amount of hormone to produce a significant
physiological effect.
, 5. The secretion of which hormone is stimulated by low blood calcium levels?
A. Calcitonin
B. Parathyroid hormone (PTH)
C. Thyroxine
D. Aldosterone
Correct Answer: B
Expert Explanation: Parathyroid hormone is secreted by the parathyroid glands in
response to hypocalcemia. It works to increase blood calcium levels by stimulating
osteoclast activity to release calcium from bone. Additionally, PTH enhances the
reabsorption of calcium in the kidneys and increases intestinal absorption via
vitamin D. This hormone is the primary regulator of calcium homeostasis in the
adult body. If PTH levels are insufficient, it can lead to muscle tetany and
neurological issues.
6. Which gland is often referred to as the ‘master gland’ because it regulates several
other endocrine glands?
A. Adrenal gland
B. Thyroid gland
C. Pancreas
4 Version 1 | Questions with Correct Answers and
Expert Explanation for Each Question | Saint Paul’s
School of Nursing
1. Which of the following describes the primary mechanism by which most hormones
are regulated in the body?
A. Positive feedback loops
B. Direct enzymatic degradation
C. Neural stimulation only
D. Negative feedback loops
Correct Answer: D
Expert Explanation: Negative feedback is the most common regulatory mechanism
in the endocrine system. It functions by detecting a change in a physiological
parameter and initiating a response to reverse that change. For instance, when
blood glucose levels rise, insulin is released to lower them back to normal. Once the
set point is reached, the production of the hormone is inhibited. This process is
essential for maintaining homeostasis throughout the entire body.
2. Which hormone is synthesized by the hypothalamus but stored and released by the
posterior pituitary gland?
A. Growth Hormone (GH)
,B. Thyroid Stimulating Hormone (TSH)
C. Antidiuretic Hormone (ADH)
D. Adrenocorticotropic Hormone (ACTH)
Correct Answer: C
Expert Explanation: Antidiuretic hormone is produced by neuronal cell bodies
located in the hypothalamus. It is then transported down axons to the posterior
pituitary for storage and eventual release. Unlike the anterior pituitary, the
posterior pituitary does not produce its own hormones. ADH plays a critical role in
regulating water balance by acting on the kidneys. This demonstrates the close
integration between the nervous and endocrine systems.
3. Steroid hormones are derived from which of the following molecules?
A. Amino acids
B. Peptides
C. Nucleic acids
D. Cholesterol
Correct Answer: D
Expert Explanation: Steroid hormones are lipid-soluble molecules that are
synthesized from cholesterol. Because they are lipids, they can easily diffuse
,through the phospholipid bilayer of target cell membranes. Examples of these
hormones include cortisol, testosterone, and estrogen. Once inside the cell, they
typically bind to intracellular receptors to influence gene expression. Their chemical
structure allows them to have long-lasting effects compared to water-soluble
hormones.
4. Which second messenger is commonly used by water-soluble hormones to trigger a
cellular response?
A. Cyclic AMP (cAMP)
B. Adenosine triphosphate (ATP)
C. Acetylcholine
D. Sodium ions
Correct Answer: A
Expert Explanation: Water-soluble hormones cannot cross the cell membrane and
must bind to receptors on the cell surface. This binding activates a G protein, which
then stimulates the enzyme adenylate cyclase. Adenylate cyclase converts ATP into
cyclic AMP, which acts as the second messenger. cAMP then activates protein
kinases that trigger a cascade of enzymatic reactions within the cell. This
amplification process allows a small amount of hormone to produce a significant
physiological effect.
, 5. The secretion of which hormone is stimulated by low blood calcium levels?
A. Calcitonin
B. Parathyroid hormone (PTH)
C. Thyroxine
D. Aldosterone
Correct Answer: B
Expert Explanation: Parathyroid hormone is secreted by the parathyroid glands in
response to hypocalcemia. It works to increase blood calcium levels by stimulating
osteoclast activity to release calcium from bone. Additionally, PTH enhances the
reabsorption of calcium in the kidneys and increases intestinal absorption via
vitamin D. This hormone is the primary regulator of calcium homeostasis in the
adult body. If PTH levels are insufficient, it can lead to muscle tetany and
neurological issues.
6. Which gland is often referred to as the ‘master gland’ because it regulates several
other endocrine glands?
A. Adrenal gland
B. Thyroid gland
C. Pancreas
