,Gartner & Hiatt: Color Textbook of Histology, 3rd Edition
Test Bank
Chapter 2 – Cytoplasm
MULTIPLE CHOICE
1. The fluidity of the plasmalemma has well-established clinical significance. Which of
the following molecules decreases the cell membrane fluidity?
a. glycerol
b. phosphate group
c. cholesterol
d. integral proteins
e. peripheral proteins
Explanation:
The answer is c. Cholesterol decreases membrane fluidity. The polar heads of
phospholipids molecules are composed of glycerol, to which a positively charged
nitrogenous group is attached by a negatively charged phosphate group. Unsaturated fatty
acyl molecules increase membrane fluidity. Integral and peripheral proteins do not have
an effect on membrane fluidity.
2. A patient suffering from asthma has difficulty breathing and is treated with albuterol, a
drug that relaxes bronchiolar smooth muscles. Albuterol acts as a(n)
a. cholinergic receptor antagonist
b. cholinergic receptor antagonist
c. adrenergic receptor antagonist
d. adrenergic receptor agonist
e. inhibitor of kinase phosphorylases
Explanation:
The answer is d. Albuterol is an agonist that acts on β2-adrenergic receptors that are
located mainly on the cell membranes of bronchial tissues and, therefore, do not have
many side effects. If it were an antagonist, then it would cause smooth muscle
constriction.
3. A patient suffering from asthma has difficulty breathing and is treated with albuterol
and ipratropium, drugs that relax bronchiolar smooth muscles. Ipratropium acts as a(n)
Explanation:
The answer is a. Ipratropium is a cholinergic receptor antagonist and interferes with the
binding of acetylcholine, a neurotransmitter, to its receptor sites on the cell membrane,
thus preventing the contraction of bronchiolar smooth muscle. The two drugs are used in
combination agonist-antagonist therapy to have the desired effect of maintaining an open
airway.
4. A 9-month-old female Jewish baby, whose parents were born in Poland, is seen by her
pediatrician because of neurologic problems, including generalized paralysis and
blindness. The pediatrician should suspect that the child is suffering from
a. spina bifida
b. cranial nerve X (vagus nerve) disorder
c. Tay-Sachs disease
d. Fabry’s disease
e. Refsum’s disease
Explanation:
The answer is c. Tay-Sachs disease affects mostly children of Eastern European Jewish
ancestry as well as certain families in Lousiana of Cajun ancestry. Children suffering
from this lysosomal-storage disease cannot catabolize GM2 gangliosides that accumulate
in their lysosomes, and the enlarged lysosomes interfere with cell function. The
interference is most problematic in the neurons of the central nervous system and causes
death by the third year of life. Neither spina bifida nor vagus nerve disorders would cause
generalized paralysis or blindness. Fabry’s disease, although a lysosomal-storage
disorder, is due to an X chromosomal defect and affects only males. Refsum’s disease is
due to the accumulation of phytanic acid, a by-product of chlorophyll metabolism, and
affects older children who already eat fresh fruits and vegetables.
5. Acid hydrolases are synthesized on the rough endoplasmic reticulum and are delivered
to the Golgi complex to be packaged and distributed to their final destination. In patients
whose protooncogenes have mutated to form ras protein–related products known as ADP-
ribosylation factor (ARF), this factor may interfere with
a. coatomer II (COP II) synthesis
b. coatomer II (COP II) assembly
c. coatomer II (COP II) dissociation from vesicles
d. clathrin synthesis
e. clathrin assembly
assembly of COP-II molecules to form coatomer on the cytoplasmic aspect of these
transfer vesicles. Synthesis of COP-II proteins as well as the disassembly of the coatomer
are not influenced by ARF. Clathrin coats mediate the endocytotic pathway as well as the
pathway that leads away from the trans Golgi network.
6. Patients with sickle cell anemia possess hemoglobin-s, a mutated form of hemoglobin.
Hemoglobin-s is
a. synthesized on free ribosomes
b. synthesized on the rough endoplasmic reticulum
c. modified in the Golgi apparatus
d. packaged in the trans Golgi network
e. stored in condensing vesicles
Explanation:
The answer is a. Hemoglobin, whether normal or mutated, is present freely in the cytosol;
therefore, it is synthesized on free ribosomes. Only proteins that are to be packaged are
synthesized on the rough endoplasmic reticulum. Because hemoglobin is not packaged, it
does not enter the Golgi apparatus.
7. A neonatal baby boy is observed to have malformed hands, feet, and skull. Additional
examination displays jaundice, hepatomegaly, and hypotonic muscles with psychomotor
retardation. The pediatrician diagnoses the disorder as cerebrohepatorenal syndrome
(Zellweger’s syndrome). This condition is due to problems with which of the following
organelles?
a. mitochondria
b. lysosomes
c. early endosomes
d. late endosomes
e. peroxisomes
Explanation:
The answer is e. Children with cerebrohepatorenal syndrome die at an early age due to
mutations in their peroxin genes that code for defective receptors that are unable to
transfer enzymes destined for peroxisomes into these organelles. Mitochondria,
lysosomes, and endosomes are not affected by this mutation.
8. A 20-year-old male seeking help from his ophthalmologist presents with deteriorating
vision in both eyes, especially his central vision. The patient also evidences cardiac
dysrythmia and an apparent demyelination of the optic nerve. The ophthalmologist
suspects Leber’s hereditary optic neuropathy, a condition caused by a point mutation that
is not X-linked but is transmitted only by females. This condition is due to problems with
which of the following?
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