Chapter 23

Question 1

The radioimmunossay (RIA) is based on competition of unlabeled and radiolabeled:

A) antibodies for binding to a hormone.
B) antibodies for binding to a receptor.
C) hormone for binding to a receptor.
D) hormone for binding to an antibody.
E) receptor for binding to a hormone.

Answer 1

D) hormone for binding to an antibody.

Question 2

One distinction between peptide and steroid hormones is that peptide hormones:

A) act through nonspecific receptors, whereas steroid hormones act through specific receptors.
B) are generally water-insoluble, whereas steroid hormones are water soluble.
C) are more stable than steroid hormones.
D) bind to cell surface receptors, whereas steroid hormones bind to nuclear receptors.
E) bind to their receptors with high affinity, whereas steroid hormones bind with low affinity.

Answer 2

D) bind to cell surface receptors, whereas steroid hormones bind to nuclear receptors.

Question 3

Insulin is an example of a(n) ____________ hormone.

A) catecholamine
B) eicosanoid
C) paracrine
D) peptide
E) steroid

Answer 3

D) peptide

Question 4

The maturation of insulin from its precursor (preproinsulin) involves:

A) acetylation.
B) oxidation.
C) phosphorylation.
D) proteolysis.
E) reduction.

Answer 4

D) proteolysis.

Question 5

Epinephrine is an example of a(n) ____________ hormone.

A) catecholamine
B) eicosanoid
C) paracrine
D) peptide
E) steroid

Answer 5

A) catecholamine

Question 6

An example of an eicosanoid hormone is:

A) epinephrine.
B) retinoic acid.
C) testosterone.
D) thromboxane.
E) thyroxine.

Answer 6

D) thromboxane.

Question 7

An example of a steroid hormone is:

A) epinephrine.
B) retinoic acid.
C) testosterone.
D) thromboxane.
E) thyroxine.

Answer 7

C) testosterone.

Question 8

Some hormones are derived from amino acids; for example, catecholamines are derived from _________
while NO is derived from ______________.

A) tyrosine; arginine
B) tryptophan; lysine
C) tyrosine; histidine
D) tryptophan; arginine
E) histidine; lysine

Answer 8

A) tyrosine; arginine

Question 9

The tropic hormones (such as thyrotropin, somatotropin, and luteinizing hormone) are produced and released by the:

A) anterior pituitary.
B) hypothalamus.
C) ovaries.
D) pancreas.
E) posterior pituitary

Answer 9

A) anterior pituitary.

Question 10

The normal sequence of action of these components of the hormonal hierarchy is:

A) adrenal cortex → hypothalamus → anterior pituitary
B) anterior pituitary → adrenal cortex → hypothalamus
C) anterior pituitary → hypothalamus → adrenal cortex
D) hypothalamus → adrenal cortex → anterior pituitary
E) hypothalamus → anterior pituitary → adrenal cortex

Question 11

In its role in the hormonal hierarchy, the hypothalamus produces and releases:

A) epinephrine.
B) insulin.
C) progesterone.
D) releasing factors.
E) thyroxine

Answer 11

D) releasing factors.

Question 12

Which of the following statements about metabolism in the mammalian liver is false?

A) Most plasma lipoproteins are synthesized in the liver.
B) The enzymatic complement of liver tissue changes in response to changes in the diet.
C) The liver synthesizes most of the urea produced in the body.
D) The presence of glucose 6-phosphatase makes liver uniquely able to release glucose into the
bloodstream.
E) Under certain conditions, most of the functions of the liver can be performed by other organs.

Answer 12

E) Under certain conditions, most of the functions of the liver can be performed by other organs.

Question 13

Glucokinase:

A) acts in the conversion of liver glycogen to glucose 1-phosphate.
B) converts fructose-6-phosphate to glucose-6-phosphate
C) converts glucose 6-phosphate to fructose 6-phosphate.
D) is a hexokinase isozyme found in liver hepatocytes.
E) is found in all mammalian tissues.

Answer 13

D) is a hexokinase isozyme found in liver hepatocytes.

Question 14

In skeletal muscle:

A) amino acids are an essential fuel.
B) at rest, fatty acids are the preferred fuel.
C) large quantities of triacylglycerol are stored as fuel.
D) phosphocreatine can substitute for ATP as the direct source of energy for muscle contraction.
E) stored muscle glycogen can be converted to glucose and released to replenish blood glucose.

Answer 14

B) at rest, fatty acids are the preferred fuel.

Question 15

In skeletal muscle, phosphocreatine functions as:

A) a reservoir of Pi for mitochondria.
B) reservoir of high-energy of phosphate to replenish ATP.
C) reservoir of amino acids for protein synthesis.
D) an electron acceptor under anaerobic conditions.
E) none of the above.

Answer 15

B) reservoir of high-energy of phosphate to replenish ATP.

Question 16

The Cori cycle is:

A) the conversion of lactate to pyruvate in skeletal muscle to drive glycogen synthesis.
B) the interconversion between glycogen and glucose l-phosphate.
C) the production of lactate from glucose in peripheral tissues with the resynthesis of glucose from
lactate in liver.
D) the synthesis of alanine from pyruvate in skeletal muscle and the synthesis of pyruvate from
alanine in liver.
E) the synthesis of urea in liver and degradation of urea to carbon dioxide and ammonia by bacteria
in the gut.

Answer 16

C) the production of lactate from glucose in peripheral tissues with the resynthesis of glucose from
lactate in liver.

Question 17

Which one of the following statements is true?

A) The brain prefers glucose as an energy source, but can use ketone bodies.
B) Muscle cannot use fatty acids as an energy source.
C) In a well-fed human, about equal amounts of energy are stored as glycogen and as
triacylglycerol.
D) Fatty acids cannot be used as an energy source in humans because humans lack the enzymes of
the glyoxylate cycle.
E) Amino acids are a preferable energy source over fatty acids.

Answer 17

A) The brain prefers glucose as an energy source, but can use ketone bodies.

Question 18

When blood glucose is abnormally high, the pancreas releases:

A) epinephrine.
B) glucagon.
C) glucose.
D) insulin.
E) trypsin.

Answer 18

D) insulin

Question 19

When blood glucose is abnormally low, the pancreas releases:

A) epinephrine.
B) glucagon.
C) glucose.
D) insulin.
E) trypsin.

Answer 19

B) glucagon.

Question 20

An elevated insulin level in the blood:

A) inhibits glucose uptake by the liver.
B) inhibits glycogen synthesis in the liver and muscle.
C) results from a below-normal blood glucose level.
D) stimulates glycogen breakdown in liver.
E) stimulates synthesis of fatty acids and triacylglycerols in the liver

Answer 20

E) stimulates synthesis of fatty acids and triacylglycerols in the liver

Question 21

The largest energy store in a well-nourished human is:

A) ATP in all tissues.
B) blood glucose.
C) liver glycogen.
D) muscle glycogen.
E) triacylglycerols in adipose tissue.

Answer 21

E) triacylglycerols in adipose tissue.

Question 22

Elevated epinephrine levels do not normally stimulate:

A) fatty acid mobilization in adipose tissue.
B) gluconeogenesis in liver.
C) glycogen breakdown in muscle.
D) glycogen synthesis in liver.
E) glycolysis in muscle

Answer 22

D) glycogen synthesis in liver.

Question 23

Epinephrine triggers an increased rate of glycolysis in muscle by:

A) activation of hexokinase.
B) activation of phosphofructokinase-1.
C) conversion of glycogen phosphorylase a to glycogen phosphorylase b.
D) inhibition of the Cori Cycle
E) the Pasteur effect

Answer 23

B) activation of phosphofructokinase-1.

Question 24

Long-term maintenance of body weight is regulated by the hormone:

A) adiposin.
B) hypothalmin.
C) leptin.
D) obesin.
E) testosterone.

Answer 24

C) leptin.

Question 25

Among its numerous metabolic effects, the protein leptin:

A) decreases the production of glucocorticoids.
B) inactivates the enzyme 5’-AMP-activated protein kinase (AMPK).
C) increases the production of sex hormones.
D) makes muscle and liver cells more sensitive to insulin.
E) raises the production of thyroid hormone.

Answer 25

D) makes muscle and liver cells more sensitive to insulin.

Question 26

The hormone leptin_________ appetite; insulin ______________appetite.

A) increases; increases
B) increases; decreases
C) decreases; increases
D) decreases; decreases
E) no effect; no effect

Answer 26

D) decreases; decreases

Question 27

The peptide hormone adiponectin, produced in adipose tissue, circulates in the blood and:

A) enhances fatty acid synthesis in liver cells.
B) increases the rate of b-oxidation of fatty acids in muscle cells.
C) inhibits glucose uptake and catabolism in muscle and liver cells.
D) reduces the transport of fatty acids into muscle cells.
E) stimulates gluconeogenesis in liver cells.

Answer 27

B) increases the rate of b-oxidation of fatty acids in muscle cells.