Question 1

Hormone X activates the cAMP second messenger system in its target cells. The greatest response by a cell would come from ________.

Accepted Answer

Hormone X activates the cAMP second messenger system in its target cells. Therefore, applying a molecule of hormone X to the extracellular fluid surrounding the cell would result in the greatest response by the cell. This is because the hormone X would bind to its receptor on the cell membrane, which would then activate the cAMP second messenger system inside the cell, leading to a cellular response. Injecting a molecule of hormone X into the cytoplasm of the cell would bypass the receptor and the cAMP second messenger system, leading to a weaker or no response. Similarly, injecting a molecule of cAMP or activated cAMP-dependent protein kinase would also bypass the receptor and have a weaker or no response.

Question 2

Which of the following best describes the neuroendocrine-to-endocrine pathway of hormone action?

Accepted Answer

In the neuroendocrine-to-endocrine pathway of hormone action, a structure within the nervous system (neuro) produces and releases a hormone that regulates the activity of an endocrine gland (endocrine). This hormone, known as a releasing hormone, stimulates the endocrine gland to release its own hormone into the bloodstream. This process is an example of how the nervous and endocrine systems work together to regulate various bodily functions.

Question 3

What property of steroid hormones allows them to cross the phospholipid bilayer?

Accepted Answer

Steroid hormones are lipid soluble, meaning they are able to pass through the hydrophobic (non-polar) region of the phospholipid bilayer without the need for a transport protein. This allows them to quickly and easily enter target cells and bind to intracellular receptors.

Question 4

Estrogen is a(n) ________.

Accepted Answer

Estrogen is a lipid-soluble hormone. It belongs to the class of steroid hormones, which are derived from cholesterol and are able to diffuse across the plasma membrane of target cells.

Question 5

Epinephrine activates ________ leading to ________.

Accepted Answer

Epinephrine activates a signal cascade that increases the production of cAMP, which can lead to the release of glucose from storage and increased blood glucose levels. This is part of the fight or flight response designed to give the body energy to respond to stress or danger.

Question 6

The effects of the hormone ecdysone on development in insects depend on the levels of which hormone?

Accepted Answer

The effects of the hormone ecdysone on development in insects are modulated by the presence of juvenile hormone. When juvenile hormone levels are high, it prevents ecdysone from triggering metamorphosis, allowing the insect to remain in its current life stage. When juvenile hormone levels decrease, ecdysone can initiate metamorphosis. Therefore, the levels of juvenile hormone play a key role in determining the timing and extent of developmental changes triggered by ecdysone.

Question 7

Which of the following are examples of amplification of a hormone signal?
I. Epinephrine initiates an enzyme cascade.
II. Steroids bind hormone-response elements in the cell and initiate transcription of many genes.
III. A quantity of 0.09 mg of growth hormone leads to a 10,000-mg weight gain in a cow.
IV. Different cell types have different receptors capable of binding the same hormone.

Accepted Answer

I) Epinephrine initiates an enzyme cascade amplifying the signal.
II) Steroids initiate the transcription of many genes, which also amplifies the signal.
III) The massive weight gain in the cow illustrates amplification of the hormone signal.
IV) Different cell types having different receptors for the same hormone allows for additional amplification of the signal.

Question 8

The steroid hormone that coordinates molting in arthropods is ________.

Accepted Answer

Ecdysone is a steroid hormone that is responsible for coordinating molting in arthropods. It is synthesized and released by the prothoracic gland during each stage of development, triggering the shedding of the old exoskeleton and the production of a new one. Glucagon, thyroxine, oxytocin, and growth hormone do not have a role in molting coordination in arthropods.

Question 9

The signal cascade activated by epinephrine leads to ________.

Accepted Answer

Epinephrine signals activate the cAMP pathway, which leads to the amplification of the signal and ultimately leads to the release of glucose from storage sites such as the liver and skeletal muscle. This process is essential in the fight-or-flight response and provides energy to the body to respond to the stressor.

Question 10

The receptor for the steroid hormone estradiol is found ________.

Accepted Answer

The receptor for the steroid hormone estradiol is primarily found within the nucleus of cells. Once activated by binding estradiol, the receptor can move into the nucleus, bind to DNA, and regulate gene expression.

Question 11

Which of the following is TRUE during a typical cAMP-type signal transduction event?

Accepted Answer

In a cAMP-type signal transduction event, the hormone binds to a receptor on the cell surface, which then activates adenylyl cyclase to produce cAMP (the second messenger). The cAMP then activates protein kinase A (PKA) through a conformational change. PKA then phosphorylates target proteins, resulting in a cellular response. Therefore, choice D is the correct option as adenylyl cyclase is activated after the hormone binds to the cell, but before protein phosphorylation occurs. Option A is incorrect as the second messenger is formed early in the signaling cascade and is necessary for the downstream events. Option B is also incorrect as the hormone does not directly bind to the second messenger, but to a receptor on the cell surface, which ultimately leads to the production of the second messenger. Option C is incorrect as the second messenger does not attract more hormones to the cell, but rather amplifies the signaling cascade by activating PKA, which then phosphorylates downstream proteins.

Question 12

In response to stress, the adrenal gland promotes the synthesis of glucose from non-carbohydrate substrates via the action of the steroid hormone ________.

Accepted Answer

The steroid hormone produced by the adrenal gland in response to stress is cortisol, which promotes the synthesis of glucose from non-carbohydrate substrates. Glucagon and epinephrine also play a role in regulating blood glucose levels, but they are not steroid hormones. Thyroxine is a thyroid hormone that regulates metabolism, but it is not directly involved in glucose synthesis. ACTH stimulates the adrenal gland to produce cortisol, but it is not the hormone responsible for glucose synthesis.

Question 13

If a person loses a large amount of water in a short period of time, he or she may die from dehydration. Antidiuretic hormone (ADH) can help reduce water loss through its interaction with its target cells in the ________.

Accepted Answer

ADH is produced in the hypothalamus and released from neurons in the posterior pituitary. Its target cells are in the kidney, where it increases the reabsorption of water, reducing water loss and helping to maintain fluid balance in the body.

Question 14

Which of the following is characteristic of a steroid hormone action?

Accepted Answer

Steroid hormones diffuse across the plasma membrane and bind to cytosolic hormone receptors, forming hormone-receptor complexes that then translocate to the nucleus and regulate gene expression. This is in contrast to peptide hormones, which typically bind to cell-surface receptors and activate second messenger pathways. Protein phosphorylation may occur as a downstream effect of hormone signaling, but it is not the defining characteristic of steroid hormone action.

Question 15

When adenylyl cyclase is activated ________.

Accepted Answer

Adenylyl cyclase is responsible for synthesizing cyclic adenosine monophosphate (cAMP) from ATP. When adenylyl cyclase is activated, it catalyzes the conversion of ATP to cAMP, which can then go on to activate downstream signaling pathways.

Question 16

Which of the following is NOT a chemical class of hormones?

Accepted Answer

Peptides and polypeptides, steroids and amino acid derivatives are all chemical classes of hormones. Complex carbohydrates are not a chemical class of hormones.

Question 17

Fight-or-flight reactions include activation of the ________.

Accepted Answer

The fight-or-flight response involves the activation of the sympathetic nervous system and the release of hormones from the adrenal medulla, including epinephrine (also known as adrenaline), which prepares the body for physical action. Choice A is incorrect because the parathyroid glands are involved in calcium regulation, not fight-or-flight responses. Choice B is incorrect because the thyroid gland is involved in metabolism and not fight-or-flight responses. Choice C is incorrect because the anterior pituitary gland is involved in the regulation of other hormones, not fight-or-flight responses. Choice E is incorrect because the pancreas is involved in sugar regulation, not fight-or-flight responses.

Question 18

After drinking alcoholic beverages, increased urine excretion is the result of ________.

Accepted Answer

Alcohol inhibits the secretion of antidiuretic hormone (ADH), leading to increased urine excretion.

Question 19

The hormone that stimulates the production of red blood cells and the organ where this hormone is synthesized are ________.

Accepted Answer

Erythropoietin is the hormone that stimulates the production of red blood cells and it is synthesized in the kidneys. Therefore, option B is the correct answer. Growth hormone is involved in the growth and development of tissues and organs, and is synthesized in the pituitary gland. Cortisol is a stress hormone that is synthesized in the adrenal gland. Epinephrine is another stress hormone that is synthesized in the adrenal gland. Acetylcholine is a neurotransmitter that is involved in muscle control and is not synthesized in the bone marrow.

Question 20

Estradiol is an example of ________.

Accepted Answer

Estradiol is a type of estrogen, a female sex hormone. Option A (androgens) are male sex hormones, option C (progestins) are female sex hormones, option D (catecholamines) are a class of neurotransmitters and option E (glucocorticoids) are a class of steroid hormones involved in regulating glucose metabolism and immune function.

Quiz 46: Chemical Signals in Animals