Deck 46: Chemical Signals in Animals

Question 1

Oxytocin and antidiuretic hormone (ADH) are synthesized in the ________.

A) hypothalamus
B) adenohypophysis
C) anterior pituitary
D) adrenal cortex
E) posterior pituitary

Answer 1

A

Question 2

If a biochemist discovers a new molecule, which of the following pieces of data would allow her to draw the conclusion that the molecule is a steroid hormone?
I) The molecule is lipid soluble.
II) The molecule is derived from a series of steps beginning with cholesterol.
III) The molecule acts at a target tissue some distance from where it is produced.
IV) The molecule uses a carrier protein when in an aqueous solution such as blood.

A) only I and III
B) only II and IV
C) only I, III, and IV
D) only II and III
E) I, II, III, and IV

Answer 2

E

Question 3

Steroid and peptide hormones typically have in common ________.

A) the building blocks from which they are synthesized
B) their solubility in cell membranes
C) their requirement for travel through the bloodstream
D) the location of their receptors
E) their reliance on signal transduction in the cell

Answer 3

C

Question 4

Polypeptides can have which of the following types of effects?
I) autocrine
II) paracrine
III) endocrine

A) only I and III
B) only II and III
C) only I and II
D) I, II, and III

Question 5

Chemical signals that act on the same cells that secrete them are called ________.

A) hormones
B) autocrine signals
C) neurohormones
D) neurotransmitters
E) paracrine signals

Question 6

Which hormone is produced from cholesterol?

A) leptin
B) luteinizing hormone
C) melanocyte-stimulating hormone
D) cortisol
E) oxytocin

Question 7

An example of two hormones that have opposite effects in maintaining homeostasis is ________.

A) thyroxine and parathyroid hormone in calcium balance
B) insulin and glucagon in glucose metabolism
C) progestins and estrogens in sexual differentiation
D) epinephrine and norepinephrine in fight-or-flight responses
E) oxytocin and prolactin in milk production

Question 8

For hormones that homeostatically regulate cellular functions, ________.

A) negative feedback typically regulates hormone secretion
B) the circulating level of a hormone is held constant through a series of positive feedback loops
C) both lipid-soluble hormones and water-soluble hormones bind to intracellular protein receptors
D) endocrine organs release their contents into the bloodstream via specialized ducts
E) it is impossible to also have neural regulation of that system

Question 9

Which of these glands has both exocrine and endocrine function?

A) thyroid
B) pituitary
C) parathyroid
D) pancreas

Question 10

In a lactating mammal, the two hormones that promote milk synthesis and milk release, respectively, are ________.

A) prolactin and calcitonin
B) prolactin and oxytocin
C) follicle-stimulating hormone and luteinizing hormone
D) luteinizing hormone and oxytocin
E) prolactin and luteinizing hormone

Question 11

Analysis of a blood sample from a fasting individual who had not eaten for 24 hours would be expected to reveal high levels of ________.

A) insulin
B) glucagon
C) secretin
D) gastrin
E) glucose

Question 12

What is the only type of chemical signal that diffuses locally and affects nearby cells?

A) hormones
B) autocrine signals
C) neurohormones
D) neurotransmitters
E) paracrine signals

Question 13

Which of the following is an endocrine gland?

A) parathyroid glands
B) salivary glands
C) sweat glands
D) sebaceous glands
E) gallbladder

Question 14

A cell with membrane-bound proteins that selectively bind a specific hormone is called the ________ for that hormone,

A) secretory cell
B) plasma cell
C) endocrine cell
D) target cell
E) regulatory cell

Question 15

Which of the following statements is (are) correct?
I) Hormones often regulate homeostasis through antagonistic functions.
II) Hormones of the same chemical class usually have the same function.
III) Hormones are secreted by specialized cells usually located in exocrine glands.
IV) Hormones are often regulated through feedback loops.

A) only I and II
B) only II and III
C) only I and III
D) only III and IV
E) only I and IV

Question 16

In experiments where researchers suspect that a hormone may be responsible for a certain physiological effect, they may cut the neurons leading to the organ where the effect being studied occurs. What is the purpose of cutting these neurons?

A) to make sure that the effect is not occurring through actions in the nervous system
B) to make sure that the organ being affected cannot function unless the researchers stimulate it with an external electrical probe
C) to impair the normal functions of the organ so that the hormonal effect can be more easily studied
D) to numb the organ so that it can be probed without inducing pain in the lab animal

Question 17

Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. Thus, testosterone is an example of ________.
I) an autocrine signal
II) a paracrine signal
III) an endocrine signal

A) only I and II
B) only II and III
C) only I and III
D) I, II, and III

Question 18

Which hormone is correctly paired with its action?

A) oxytocin-stimulates uterine contractions during childbirth
B) thyroxine-affects biological rhythms, seasonal reproduction
C) insulin-stimulates glycogen breakdown in the liver
D) adrenocorticotropic hormone (ACTH) -stimulates metabolic processes
E) melatonin-stimulates the release of glucocorticoids by the adrenal cortex

Question 19

Which of the following has both endocrine and exocrine activity?

A) the pituitary gland
B) parathyroid glands
C) salivary glands
D) the pancreas
E) adrenal glands

Question 20

Most animal hormones ________.

A) are produced by endocrine glands
B) are lipid-soluble molecules
C) are carried to target cells in the blood or hemolymph
D) are protein molecules
E) elicit the same biological response from all of their target cells

Question 21

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

A) applying a molecule of hormone X to the extracellular fluid surrounding the cell
B) injecting a molecule of hormone X into the cytoplasm of the cell
C) applying a molecule of cAMP to the extracellular fluid surrounding the cell
D) injecting a molecule of cAMP into the cytoplasm of the cell
E) injecting a molecule of activated, cAMP-dependent protein kinase into the cytoplasm of the cell

Question 22

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

A) A structure within the nervous system produces and release a hormone that regulate the activity of an endocrine gland.
B) A structure within the nervous system produces a hormone and releases it directly onto an endocrine gland.
C) A gland releases hormones directly into a neural structure, thus regulating neural functions.
D) A gland exhibits negative feedback on the nervous system by releasing hormones into neural tissue both directly and indirectly through the circulation.

Question 23

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

A) Steroid hormones are lipid soluble and easily cross the phospholipid bilayer.
B) Steroid hormones can act in very small concentrations and very few molecules of steroids need to cross the lipid bilayer.
C) Steroid hormones act on cells close to where they were produced and very few molecules are required to travel such a short distance to cross the lipid bilayer.
D) Steroid hormones act on the same cells in which they are produced and, therefore, are within the cell they are acting upon.

Question 24

Estrogen is a(n) ________.

A) peptide hormone
B) amine derivative
C) lipid-soluble hormone
D) iodinated protein hormone made by the thyroid gland
E) gaseous neurotransmitter

Question 25

Epinephrine activates ________ leading to ________.

A) aquaporin activity; increased reabsorption of water
B) the thyroid gland; increased metabolism
C) hormone production by the testes; development of secondary sex characteristics
D) a cAMP signal cascade; increased blood glucose
E) reduced activity by the anterior pituitary; reduced growth

Question 26

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

A) thyroxine
B) juvenile hormone
C) oxytocin
D) brain hormone
E) prothoracic hormone

Question 27

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.

A) only I and III
B) only II and IV
C) only I, II, and III
D) only II and III
E) I, II, III, and IV

Question 28

The steroid hormone that coordinates molting in arthropods is ________.

A) ecdysone
B) glucagon
C) thyroxine
D) oxytocin
E) growth hormone

Question 29

The signal cascade activated by epinephrine leads to ________.

A) the amplification of the epinephrine signal, increasing the release of glucose
B) the reduction in metabolic rate through down-regulation of thyroid activity
C) the amplification of the epinephrine signal, increasing the release of calcium from bone
D) the cessation of fight-or-flight response by activating the parasympathetic response

Question 30

The receptor for the steroid hormone estradiol is found ________.

A) on the cell membrane
B) within the cytoplasm
C) as an extracellular element in the blood
D) primarily within the nucleus
E) either within the cytoplasm or the nucleus

Question 31

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

A) The second messenger is the last part of the system to be activated.
B) The hormone activates the second messenger by directly binding to it.
C) The second messenger amplifies the hormonal response by attracting more hormones to the cell being affected.
D) Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.

Question 32

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

A) glucagon
B) cortisol
C) epinephrine
D) thyroxine
E) adrenocorticotropic hormone (ACTH)

Question 33

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 ________.

A) anterior pituitary
B) posterior pituitary
C) adrenal gland
D) bladder
E) kidney

Question 34

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

A) protein phosphorylation
B) cell-surface hormone receptor binding
C) cytosolic hormone receptor binding
D) second messenger activation

Question 35

When adenylyl cyclase is activated ________.

A) cAMP is synthesized
B) cAMP is degraded
C) G proteins bind to cAMP
D) steroid hormones pass through the lipid bilayer

Question 36

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

A) peptides and polypeptides
B) complex carbohydrates
C) steroids
D) amino acid derivatives

Question 37

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

A) parathyroid glands, leading to increased metabolic rate
B) thyroid gland, leading to an increase in the blood calcium concentration
C) anterior pituitary gland, leading to cessation of gonadal function
D) adrenal medulla, leading to increased secretion of epinephrine
E) pancreas, leading to a reduction in the blood sugar concentration

Question 38

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

A) increased aldosterone production
B) increased blood pressure
C) inhibited secretion of antidiuretic hormone (ADH)
D) increased reabsorption of water in the proximal tubule
E) the osmoregulator cells of the brain increasing their activity

Question 39

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

A) growth hormone and pancreas, respectively
B) erythropoietin and kidney, respectively
C) cortisol and adrenal gland, respectively
D) epinephrine and adrenal gland, respectively
E) acetylcholine and bone marrow, respectively

Question 40

Estradiol is an example of ________.

A) an androgen
B) an estrogen
C) a progestin
D) a catecholamine
E) a glucocorticoid

Question 41

Which of the following is an example of negative feedback?

A) During birthing contractions, oxytocin is released and acts to stimulate further contractions.
B) When a baby is nursing, suckling leads to the production of more milk and a subsequent increase in the secretion of prolactin.
C) A stressful stimulus leads to the release of epinephrine, which increases fatty acid and glucose in the blood and cardiovascular activity.
D) When the level of glucose in the blood increases, the pancreas produces and releases the hormone insulin. Insulin acts to decrease blood glucose. As blood glucose decreases, the rate of production and release of insulin decreases.

Question 42

During a stressful interval, ________.

A) thyroid-stimulating hormone (TSH) stimulates the adrenal cortex and medulla to secrete acetylcholine
B) the alpha cells of islets secrete insulin and simultaneously the beta cells of the islets secrete glucagon
C) adrenocorticotropic hormone (ACTH) stimulates the adrenal cortex, and neurons of the sympathetic nervous system stimulate the adrenal medulla
D) the posterior pituitary gland secretes more growth hormones
E) the calcium levels in the blood are increased due to actions of two antagonistic hormones, epinephrine and norepinephrine

Question 43

A physician finds that a 9-year-old male patient is entering puberty much earlier than is usual. Such a condition is most likely the result of a tumor in the ________.

A) hypothalamus, directly producing elevated levels of testosterone
B) anterior pituitary, directly producing elevated levels of testosterone
C) testes, directly producing elevated levels of estrogen
D) anterior pituitary, directly producing elevated levels of gonadotropin-stimulating hormone

Question 44

During puberty, the development of sex-specific traits results from a surge of ________ in boys and ________ and girls.

A) testosterone; cortisol
B) juvenile hormone; estradiol
C) estradiol; ecdysone
D) testosterone; estradiol
E) male growth hormone; female growth hormone

Question 45

Hormones secreted by the posterior pituitary gland are made in the ________.

A) cerebrum
B) cerebellum
C) thalamus
D) hypothalamus
E) medulla oblongata

Question 46

Tadpoles must undergo a major metamorphosis to become frogs. This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in hemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by triiodothyronine. What is the most likely explanation for such a wide array of effects of thyroxine?

A) There are many different forms of triiodothyronine, each specific to a different tissue.
B) Different tissues have triiodothyronine receptors that activate different signal transduction pathways.
C) Some tissues have membrane receptors for triiodothyronine, while other tissues have triiodothyronine receptors within the nucleus.
D) Different releasing hormones release triiodothyronine to different tissues.

Question 47

A tumor that decreases the production of adrenocorticotropic hormone (ACTH) would lead to a decrease in plasma levels of ________.

A) glucocorticoid hormones
B) epinephrine
C) corticotropin-releasing hormone
D) testosterone
E) acetylcholine

Question 48

Xenoestrogens are an example of what group of chemicals described by Rachel Carson in her book Silent Spring?

A) glucocorticoids
B) sex hormones
C) endocrine disruptors
D) stress hormones
E) mineralcorticoids

Question 49

The interrelationships between the endocrine and the nervous systems are especially apparent in a ________.

A) neuron in the spinal cord
B) steroid-producing cell in the adrenal cortex
C) neurosecretory cell in the hypothalamus
D) brain cell in the cerebral cortex
E) cell in the pancreas that produces digestive enzymes

Question 50

The increased contraction of the human uterus during labor and delivery is at least partially due to the actions of ________.

A) ecdysone
B) glucagon
C) thyroxine
D) oxytocin
E) growth hormone

Question 51

Predict the immediate effects of a drug that increases adrenocorticotropic hormone (ACTH) synthesis.

A) increase in glucocorticoid production
B) increase in release of corticotropin-releasing hormone (CRH)
C) decrease in cortisol release
D) decrease in release of corticotropin-releasing hormone (CRH)

Question 52

The regulation of blood sugar levels and our stress responses are controlled in part by a negative feedback loop involving cortisol, adrenocorticotropic hormone (ACTH), and corticotropin-releasing hormone (CRH). What would likely be the result during times of stress if cortisol receptors in the hypothalamus were nonfunctional?

A) Blood sugar levels would rise to dangerous levels.
B) Blood sugar levels would be unaffected.
C) ACTH production would cease.
D) CRH production would cease.
E) Cortisol production would cease.

Question 53

Glucocorticoids do which of the following?

A) promote the immune response
B) promote the release of fatty acids
C) increase blood glucose levels
D) increase insulin production

Question 54

Neurons in the hypothalamus regulate the activity of secretory cells in the anterior pituitary gland by ________.

A) forming synapses on cells in the anterior pituitary
B) releasing regulatory hormones that increase activity in the adrenal medulla
C) forming synapses on the adrenal gland that in turn regulates the pituitary
D) secreting releasing hormones into special blood vessels that connect the hypothalamus to the pituitary
E) releasing oxytocin

Question 55

Antidiuretic hormone (ADH) functions at the cellular level by ________.

A) stimulating the reabsorption of glucose through channel proteins
B) triggering the synthesis of an enzyme that makes the phospholipid bilayer more permeable to water
C) causing membranes to include more phospholipids that have unsaturated fatty acids
D) activating aquaporin molecules of collecting duct cells
E) decreasing the speed at which filtrate flows through the nephron, leading to increased

Question 56

The release of hormones by the posterior pituitary is the result of what process?

A) The anterior pituitary regulates the activity of the posterior pituitary gland.
B) The release of regulatory hormones increases activity in the adrenal medulla, altering the activity of the posterior pituitary.
C) Neurosecretory cells of the hypothalamus directly release hormones into blood vessels within the posterior pituitary.
D) Hypothalamic neurons form synapses on the adrenal gland, which in turn regulates the pituitary.
E) Releasing hormones from the hypothalamus directs the production and release of oxytocin from the posterior pituitary.

Question 57

Oxytocin helps initiate labor in mammals. During labor and delivery, the contraction of uterine muscles increases the release of oxytocin. This is an example of ________.

A) a negative feedback system
B) a hormone that acts in an antagonistic way with another hormone
C) a hormone that is involved in a positive feedback loop
D) signal transduction immediately changing gene expression in its target cells
E) the key role of the anterior pituitary gland in regulating uterine contraction

Question 58

In human embryonic development, which of the following pairs of hormones are released by the developing testes and result in development of the male reproductive tract and inhibition of the female reproductive tract?

A) testosterone and estrogen
B) estrogen and progesterone
C) testosterone and Müllerian inhibitory substance
D) estradiol and estrogen
E) testosterone and estradiol

Question 59

Removing which of the following glands would have the most wide-reaching effect on bodily functions of an adult human?

A) adrenal glands
B) pituitary gland
C) thyroid gland
D) ovaries (in female) or testes (in male)