Chapter 20 Practice Questions

A water-soluble hormone binds to its receptor on the plasma membrane. Arrange the events that follow in correct sequence. (1) Alpha subunit-GTP complex alters cell activity (2) GTP binds to the alpha subunit replacing GDP (3) G-protein subunits separate from the receptor (4) Alpha subunit separates from other two subunits (5) G-protein subunits bind to the receptor A) 5, 2, 3, 4, 1 B) 4, 2, 1, 3, 5 C) 5, 2, 1, 4, 3 D) 5, 4, 2, 1, 3 E) 3, 4, 1, 2, 5

A) 5, 2, 3, 4, 1

Hormone A has entered the cell and binds to a nuclear receptor, while hormone B binds to a membrane receptor on the outside of the cell. Which statement is TRUE? (Check all that apply.) A) Hormone A is in the lipid-soluble category. B) Hormone B is in the lipid-soluble category. C) Hormone B will stimulate the activation of a G protein. D) Hormone A will cause the formation of cAMP.

A) Hormone A is in the lipid-soluble category. C) Hormone B will stimulate the activation of a G protein.

Which chemical type of hormone has a longer half-life? A) Lipid-soluble B) Protein C) Water-soluble D) Amino acid derivative

A) Lipid-soluble

Which type of chemical messenger will act locally on nearby cells? A) Paracrine B) Neurotransmitter C) Autocrine D) Endocrine

A) Paracrine

What is it about a cell that identifies it as a target cell for a hormone? A) The presence of a receptor specific for that hormone B) Its location near the gland that secretes that hormone C) The ability of the target cell to perform a specific function D) Its ability to inactivate the hormone E) The size of the target cell

A) The presence of a receptor specific for that hormone

When a few intracellular mediator molecules activate several enzymes, and each of these activated enzymes activate still other enzymes, the hormone has initiated __________. A) a cascade effect B) a double loop effect C) a protein kinase effect D) a cyclic effect E) a negative feedback cycle

A) a cascade effect

The role of cAMP when it acts as an intracellular mediator in cells is to A) bind to and activate protein kinase. B) directly activate genes in the nucleus to produce mRNA by binding to DNA. C) directly activate structural enzymes in the cytoplasm of the target cell. D) catalyze a cascade reaction that ultimately activates genes on the DNA. E) control levels of calcium in the cell.

A) bind to and activate protein kinase.

Which intracellular mediator is directly activated by the binding of a water-soluble hormone to a membrane receptor? A) cGMP B) cAMP C) Calmodulin D) Phospholipase C

A) cGMP

Secretion of one hormone by the action of another hormone is control by_________ stimuli. A) hormonal B) neural C) humoral D) visceral

A) hormonal

Most hormones are regulated by_________ mechanisms. A) negative-feedback B) neural-feedback C) positive-feedback D) hormonal-feedback

A) negative-feedback

In general, the response of target cells to endocrine stimulation is_________ than their response to nervous stimulation. A) faster and briefer B) slower and more prolonged C) more accurate D) more restricted to a small area of the body E) more intense

B

Considering the following events in the nuclear receptor model, identify which of these events occurs in the nucleus. (1) Hormone receptor complex binds to DNA. (2) Messenger RNA directs synthesis of specific proteins. (3) Hormone binds to receptors in the nucleus (sometimes in the cytoplasm). (4) Messenger RNA synthesis is activated. (5) Synthesized proteins produce the response of the cell. A) 1, 3, 5 B) 1, 3, 4 C) 1, 2, 3 D) 3, 4, 5 E) All events occur in the nucleus.

B) 1, 3, 4

Arrange the following events in proper sequence: (1) The activating hormone interacts with a membrane-bound receptor. (2) Cyclic AMP causes the cell to carry out a function characteristic for that specific hormone. (3) Adenylyl cyclase catalyzes the transformation of ATP to cyclic AMP. (4) Adenylyl cyclase is activated. A) 1, 2, 3, 4 B) 1, 4, 3, 2 C) 3, 4, 2, 1 D) 1, 3, 2, 4E) 1, 3, 4, 2

B) 1, 4, 3, 2

Which of the following occurs when a hormone binds to a nuclear receptor? A) Activation of cyclic AMP B) Activation of mRNA synthesis C) Increased lipid synthesis by ribosomes D) Opens membrane channels E) Alters membrane permeability

B) Activation of mRNA synthesis

Which pattern of hormone secretion, often observed in steroid reproductive hormones, will fluctuate over a monthly cycle? A) Acute hormone secretion B) Episodic hormone secretion C) Long-term hormone secretion D) Chronic hormone secretion

B) Episodic hormone secretion

Which type of chemical messenger is released from neurons to activate an adjacent cell? A) Paracrine B) Neurotransmitter C) Autocrine D) Endocrine

B) Neurotransmitter

Most endocrine glands communicate with their target tissues using_________ signals. A) frequency-modulated B) amplitude-modulated C) pitch-modulated D) resonance-modulated

B) amplitude-modulated

When a hormone binds to a membrane-bound receptor, A) membrane channels are destroyed. B) cyclic GMP might be produced to act as an intracellular mediator. C) the nucleus is phosphorylated to prevent G-protein activation. D) messenger RNA is formed.E) cellular DNA is altered.

B) cyclic GMP might be produced to act as an intracellular mediator.

Steroid hormones A) bind to membrane receptors. B) diffuse easily through the plasma membrane. C) act by activating cAMP. D) are inactivated by phosphodiesterase. E) are water soluble.

B) diffuse easily through the plasma membrane.

Once a lipid-soluble hormone is conjugated in the liver A) its half-life is increased. B) it can be more quickly eliminated from the body. C) it can be stored for later use. D) it is actively transported into cells. E) it is more slowly eliminated from the body.

B) it can be more quickly eliminated from the body.

Receptors for most water-soluble hormones are located A) in the cytoplasm of their target cells. B) on the plasma membrane of their target cells. C) in the lysosomes of their target cells. D) on the nuclear membrane of their target cells. E) on the endoplasmic reticulum of their target cells.

B) on the plasma membrane of their target cells.

Up-regulation A) results in a decrease in the number of receptor sites in the target cell. B) produces an increase in the sensitivity of the target cell to the hormone. C) is found in target cells that maintain a constant level of receptors. D) produces insensitivity to the hormone in the target tissue. E) moves the receptors up on the membrane.

B) produces an increase in the sensitivity of the target cell to the hormone.

The endocrine system A) releases neurotransmitters into ducts. B) secretes chemicals that reach their targets through the bloodstream. C) communicates via frequency-modulated signals. D) contains organs called exocrine glands. E) is isolated from the nervous system.

B) secretes chemicals that reach their targets through the bloodstream.

Phosphodiesterase functions A) as a membrane-bound receptor molecule. B) to inactivate cyclic AMP. C) to attach phosphate groups to enzymes. D) to combine GTP with cyclic AMP. E) activates cGMP.

B) to inactivate cyclic AMP.

Given the following list of organic molecules, which includes hormones? 1) Nucleic acid derivatives 2) Polypeptides 3) Steroids 4) Proteins A) 1, 3, 4 B) 1, 2, 3 C) 2, 3, 4 D) 1, 2, 3, 4 E) 1, 2, 4

C) 2, 3, 4

Which type of chemical messenger stimulates the cell that originally secreted it? A) Paracrine B) Neurotransmitter C) Autocrine D) Endocrine

C) Autocrine

How do hormones and target cells recognize one another? A) By signs B) By the location of the target cells C) By the presence of specific receptor molecules on or in the target cells D) By the function of the target cells E) By the location of the hormones

C) By the presence of specific receptor molecules on or in the target cells

Which of the following events occurs last? A) IP3 (inositol triphosphate) is produced. B) Epinephrine combines with membrane-bound receptor on smooth muscle cell. C) Calmodulin binds to the enzyme that phosphorylates myosin and cross-bridges form. D) IP3 stimulates Ca2+ release from the endoplasmic reticulum. E) Ca2+ binds with calmodulin.

C) Calmodulin binds to the enzyme that phosphorylates myosin and cross-bridges form.

Which pattern of hormone secretion, exemplified by thyroid hormones, remains relatively constant over long periods of time? A) Acute hormone secretion B) Episodic hormone secretion C) Chronic hormone secretion D) Long-term hormone secretion

C) Chronic hormone secretion

Cortisol, a lipid-soluble hormone is released into the blood. Predict what cortisol might do. A) Cortisol will dissolve in the blood as free hormone. B) Cortisol needs fenestrated capillaries to move out of the blood stream. C) Cortisol will readily diffuses through capillary wall. D) Cortisol will be rapidly degraded by proteases in the bloodstream. E) Cortisol may have carbohydrates attached to give a longer half-life.

C) Cortisol will readily diffuses through capillary wall.

Which of the following statements regarding hormone transport and distribution is FALSE? A) Only free hormones can diffuse through capillary walls and bind to target tissues. B) Hormones can be transported free in the plasma or bound to plasma proteins. C) Plasma protein concentration has no influence on free hormone concentration. D) Hormones bind only to certain types of plasma proteins. E) All of the statements are true.

C) Plasma protein concentration has no influence on free hormone concentration.

What do all hormones have in common? A) They are made from amino acids. B) They are bound to transport molecules in the blood. C) They bind to and interact with a receptor on or in the target cell. D) They use the second messenger mechanism to control the target cell. E) They are all lipid-soluble.

C) They bind to and interact with a receptor on or in the target cell.

Lipid-soluble hormones can be more easily excreted once they have water-soluble molecules added to their structure in a process called_________. A) saponification B) amplitude-modulation C) conjugation D) protein-binding

C) conjugation

In some forms of diabetes, an insensitivity to insulin seems to be present. This insensitivity could be the result of_________. A) up-regulation B) over-regulation C) down-regulation D) a lack of regulation E) modulation

C) down-regulation

Hormones are intercellular chemical signals that A) are secreted into the external environment where they act. B) affect only non-hormone producing organs or tissues. C) help coordinate growth, development and reproduction. D) operate primarily by positive feedback.

C) help coordinate growth, development and reproduction.

Parathyroid hormone is released when blood calcium levels decrease. This is an example of control by_________ stimuli. A) hormonal B) neural C) humoral D) visceral

C) humoral

The half-life of a hormone allows one to determine A) the rate of hormone secretion. B) the identity of a hormone. C) the rate at which hormones are eliminated from the body. D) the rate of action of a hormone. E) the rate of travel through the blood to a target.

C) the rate at which hormones are eliminated from the body.

Which pattern of hormone secretion, represented by epinephrine, can have dramatic changes in its concentration and circulating levels? A) Chronic hormone secretion B) Long-term hormone secretion C) Episodic hormone secretion D) Acute hormone secretion

D) Acute hormone secretion

Hormonal secretion can be regulated by A) the action of a substance other than a hormone. B) the nervous system. C) other hormones. D) All of the choices are correct. E) None of the choices are correct.

D) All of the choices are correct.

Hormone receptor molecules may be_________ in order to change the target cell's sensitivity to a given hormone. A) increased in number B) decreased in number C) chemically altered D) All the choices are correct.

D) All the choices are correct.

How do most water-soluble hormones travel in the bloodstream? A) Attached to proteins B) Attached to carbohydrates C) Attached to amino acids D) As free hormones

D) As free hormones

Which of the following statements about the endocrine system is NOT true? A) The hypothalamus is important to both the nervous and endocrine systems. B) Both the nervous and endocrine systems may utilize the same chemical molecule. C) Some neurons secrete hormones. D) Both the nervous and endocrine systems respond quickly and are active for a long time.

D) Both the nervous and endocrine systems respond quickly and are active for a long time.

Which of the following is a regulatory protein associated with membrane-bound receptor molecules? A) ATP B) Calcium C) M protein D) G protein E) DNA

D) G protein

Which chemical class of hormone is more likely to need a binding protein for transport in the blood? A) Water-soluble B) Amino acid derivative C) Protein D) Lipid-soluble

D) Lipid-soluble

Which type of hormone-receptor action allows insulin to move glucose into cells? A) Activation of cGMP B) Activation of adenylate cyclase C) Direct alteration of intracellular enzymes D) Phosphorylation of intracellular proteins

D) Phosphorylation of intracellular proteins

Members of which group of hormones are made from cholesterol? A) Amino acid derivatives B) Peptides C) Proteins D) Steroids

D) Steroids

All of the following chemical messengers may be listed in multiple functional classes except _________. A) eicosanoids B) epinephrine C) prostaglandins D) acetylcholine

D) acetylcholine

All of the following are characteristics of hormones except A) hormones alter activity in target cells. B) hormones interact specifically with receptors. C) hormones are stable in blood until arrival at target cells. D) hormones interact with any cells in contact with bloodstream.

D) hormones interact with any cells in contact with bloodstream.

Blood chemistry changes are examples of _________ stimuli, whereas sympathetic nervous system impulses are examples of _________ stimuli for hormone release. A) neural; humoral B) positive; negative C) negative; positive D) humoral; neural

D) humoral; neural

A chemical produced in a cell that activates specific processes in response to a hormone interaction with a membrane-bound receptor is referred to as a/an _________. A) hormone response element B) transcription factor C) messenger RNA D) intracellular mediator

D) intracellular mediator

Sympathetic neurons can serve as _________ stimuli for hormone release from certain endocrine organs. A) autocrine B) humoral C) paracrine D) neural

D) neural

An intercellular chemical signal that is produced by neurons but functions like a hormone would be called a_________. A) neuropathogen B) neurotransmitter C) neurocrine D) neuropeptide E) neurosynthesizer

D) neuropeptide

The release of chemicals from an endocrine or exocrine gland is referred to as_________. A) absorption B) diffusion C) filtration D) secretion

D) secretion

All of the following are reasons why some hormones need assistance to travel in the blood except A) they are small enough to be easily digested by blood enzymes. B) they are easily filtered from the blood into the kidney tubules. C) they have low solubility in blood plasma due to their chemical nature. D) they cannot dissolve in the blood because they are water-soluble.

D) they cannot dissolve in the blood because they are water-soluble.

In _________, a cell increases the number of hormone receptors and becomes more sensitive to the hormone. A) amplification B) positive feedback C) down-regulation D) up-regulation

D) up-regulation

When a hormone binds to a membrane-bound receptor and activates G proteins, A) ion channels could be opened. B) IP3 may be activated. C) cyclic AMP production may be increased. D) DAG may be activated. E) All of the choices are correct.

E) All of the choices are correct.

In general, lipid-soluble hormones exhibit which type(s) of hormone secretion pattern(s)? A) Chronic hormone secretion B) Chronic and acute hormone secretion C) Acute and episodic hormone secretion D) Episodic hormone secretion E) Chronic and episodic hormone secretion

E) Chronic and episodic hormone secretion

Receptors for most lipid-soluble hormones are located A) in the cytoplasm of their target cells. B) on the plasma membrane of their target cells. C) in the lysosomes of their target cells. D) on the nuclear membrane of their target cells. E) in the nucleus or cytoplasm of their target cells.

E) in the nucleus or cytoplasm of their target cells.

Hormones with short half-lives A) are usually lipid-soluble. B) are maintained at relatively constant levels. C) have concentrations that increase slowly. D) regulate activities of delayed onset and long duration. E) regulate activities of rapid onset and short duration.

E) regulate activities of rapid onset and short duration.

The length of time needed to eliminate half of a dose of a hormone is called its_________

Half-life

Increasing levels of thyroid hormones decrease TSH levels. This is an example of_________ feedback.

negative

_________ chemical signals are released by cells and affect other cell types locally without being transported in blood.

paracrine

Hormones act on specific tissues called_________ tissues.

target