BIO-1407 Lectures 13 & 14

Which of the following is classified as a steroid hormone?

• Insulin
• Thyroxine
• Prolactin
• Cortisol

Answer explanation

Cortisol is a steroid hormone derived from cholesterol, produced by the adrenal cortex. Insulin and prolactin are amino acid-based hormones, and thyroxine, though derived from amino acids, is not a steroid.

What is the function of a second messenger in hormone action?

• It degrades hormones after use
• It transports hormones in the blood
• It binds directly to DNA
• It relays a hormone’s signal inside the cell

Answer explanation

A second messenger, such as cyclic AMP, is generated when a hormone binds to a receptor on the cell surface. It relays the signal within the cell to trigger a physiological response.

Which hormone is released from the posterior pituitary gland?

• Thyroid-stimulating hormone (TSH)
• Growth hormone
• Prolactin
• Antidiuretic hormone (ADH)

Answer explanation

ADH (antidiuretic hormone) is stored and released by the posterior pituitary, while growth hormone, prolactin, and TSH are produced by the anterior pituitary.

Tags

NGSS.HS-LS1-3

A patient with hypersecretion of growth hormone during childhood will likely develop:

• Cretinism
• Acromegaly
• Gigantism
• Myxedema

Answer explanation

Hypersecretion of growth hormone in children results in gigantism, characterized by excessive growth. Acromegaly occurs in adults, and cretinism/myxedema are thyroid-related disorders.

Which non-endocrine organ produces the hormone erythropoietin?

• Kidney
• Liver
• Skin
• Heart

Answer explanation

The kidney produces erythropoietin, which stimulates red blood cell production. The heart produces ANP, the skin produces cholecalciferol, and the liver produces somatomedins among others.

Tags

NGSS.HS-LS1-3

Which of the following best explains why only certain cells respond to a particular hormone?

• Only those cells are close to the hormone’s source
• Only those cells have specific receptors for the hormone
• Only those cells have a blood supply
• Only those cells secrete the hormone themselves

Answer explanation

Target cells have specific receptors for a hormone. If a cell lacks the receptor, it will not respond, regardless of proximity or blood supply.

Which sequence correctly describes the order of events in the cAMP second messenger system?

• Hormone binds receptor → cAMP produced → G protein activated → Adenylate cyclase activated
• G protein activated → Hormone binds receptor → Adenylate cyclase activated → cAMP produced
• Hormone binds receptor → G protein activated → Adenylate cyclase activated → cAMP produced
• Adenylate cyclase activated → Hormone binds receptor → cAMP produced → G protein activated

Answer explanation

First, hormone binds to its receptor, which activates a G protein. The G protein then activates adenylate cyclase, which converts ATP to cAMP (the second messenger).

Negative feedback is illustrated by which scenario?

• Low blood calcium stimulates PTH release, which raises calcium and inhibits further PTH secretion
• An increase in blood glucose stimulates more insulin secretion indefinitely
• High blood pressure causes continued ADH release
• High TSH levels stimulate more TSH release

Answer explanation

Negative feedback occurs when a hormone corrects a condition and the correction inhibits further hormone release. In this case, rising blood calcium levels inhibit PTH release after calcium has increased.

Tags

NGSS.HS-LS1-3

Cretinism in children is caused by a deficiency of:

• Prolactin
• Growth hormone
• Parathyroid hormone
• Thyroid hormone

Answer explanation

Cretinism is a condition of stunted physical and mental growth due to thyroid hormone deficiency during early development.

Which would most likely inhibit the release of antidiuretic hormone (ADH)?

• Feeling pain
• Drinking large amounts of water
• Taking morphine
• Experiencing low blood pressure

Answer explanation

ADH secretion is inhibited by excess water intake; the body does not need to retain water. Low blood pressure, pain, and morphine actually stimulate ADH release.

Tags

NGSS.HS-LS1-3