114
UNIT 1
Organization of the Body
Apoptosis and Modified Rates of Cell Division
(p. 110)
2.
Apoptosis is programmed cell death. Its function is to dispose of
damaged or unnecessary cells.
3.
During adulthood, cell numbers remain fairly constant. Cell
division occurs primarily to replace lost cells.
Cell Aging
(p. 111)
4.
Cellular aging may reflect chemical insults, progressive disorders
of immunity, or a genetically programmed decline in the rate of
cell division with age.
15.
Soluble proteins that are damaged or no longer needed are
targeted for destruction by attachment of ubiquitin. Cytosolic
enzymes or proteasomes then degrade these proteins.
Extracellular Materials
(p. 110)
1.
Extracellular materials are substances found outside the cells. Tey
include body fluids, cellular secretions, and extracellular matrix.
Extracellular matrix is particularly abundant in connective tissues.
Developmental Aspects of Cells
(pp. 110–111)
1.
Te first cell of an organism is the fertilized egg. Early in
development, cell specialization begins and reflects differential
gene activation.
Multiple Choice/Matching
(Some questions have more than one correct answer. Select the best
answer or answers from the choices given.)
1.
Te smallest unit capable of life by itself is
(a)
the organ,
(b)
the
organelle,
(c)
the tissue,
(d)
the cell,
(e)
the nucleus.
2.
Te major types of lipid found in the plasma membranes are
(choose two) (
a)
cholesterol,
(b)
triglycerides,
(c)
phospholipids,
(d)
fat-soluble vitamins.
3.
Membrane junctions that allow nutrients or ions to flow from cell
to cell are
(a)
desmosomes,
(b)
gap junctions,
(c)
tight junctions,
(d)
all of these.
4.
Te term used to describe the type of solution in which cells will
lose water to their environment is
(a)
isotonic,
(b)
hypertonic,
(c)
hypotonic,
(d)
catatonic.
5.
Osmosis always involves
(a)
a selectively permeable membrane,
(b)
a difference in solvent concentration,
(c)
diffusion,
(d)
active
transport,
(e)
a, b, and c.
6.
A physiologist observes that the concentration of sodium inside a
cell is decidedly lower than that outside the cell. Sodium diffuses
easily across the plasma membrane of such cells when they are
dead, but
not
when they are alive. What cellular function that
is lacking in dead cells explains the difference?
(a)
osmosis,
(b)
diffusion,
(c)
active transport (solute pumping),
(d)
dialysis.
7.
Te solute-pumping type of active transport is accomplished
by
(a)
exocytosis,
(b)
phagocytosis,
(c)
electrical forces in the
cell membrane,
(d)
changes in shape and position of carrier
molecules in the plasma membrane.
8.
Te endocytotic process in which a sampling of particulate
matter is engulfed and brought into the cell is called
(a)
phagocytosis,
(b)
pinocytosis,
(c)
exocytosis.
9.
Which is
not
true of centrioles?
(a)
Tey start to duplicate in G
1
,
(b)
they lie in the centrosome,
(c)
they are made of microtubules,
(d)
they are membrane-walled barrels lying parallel to each other.
10.
Te nuclear substance composed of histone proteins and DNA is
(a)
chromatin,
(b)
the nucleolus,
(c)
nuclear sap, or nucleoplasm,
(d)
nuclear pores.
11.
Te information sequence that determines the nature of a protein
is the
(a)
nucleotide,
(b)
gene,
(c)
triplet,
(d)
codon.
12.
Mutations may be caused by
(a)
X rays,
(b)
certain chemicals,
(c)
radiation from ionizing radioisotopes,
(d)
all of these.
13.
Te phase of mitosis during which centrioles reach the poles
and chromosomes attach to the spindle is
(a)
anaphase,
(b)
metaphase,
(c)
prophase,
(d)
telophase.
14.
Final preparations for cell division are made during the life cycle
subphase called
(a)
G
1
,
(b)
G
2
,
(c)
M,
(d)
S.
15.
Te RNA synthesized on one of the DNA strands is
(a)
mRNA,
(b)
tRNA,
(c)
rRNA,
(d)
all of these.
16.
Te RNA species that travels from the nucleus to the cytoplasm
carrying the coded message specifying the sequence of amino
acids in the protein to be made is
(a)
mRNA,
(b)
tRNA,
(c)
rRNA,
(d)
all of these.
17.
If DNA has a sequence of AAA, then a segment of mRNA
synthesized on it will have a sequence of
(a)
±±±,
(b)
UUU,
(c)
GGG,
(d)
CCC.
18.
A nerve cell and a lymphocyte are presumed to differ in their
(a)
specialized structure,
(b)
suppressed genes and embryonic
history,
(c)
genetic information,
(d)
a and b,
(e)
a and c.
19.
A pancreas cell makes proteins (enzymes) that it releases to the
small intestine. Which of the following best describes the path
of these proteins from synthesis to exocytosis at the pancreatic
cell’s plasma membrane (PM)?
(a)
Golgi
S
rough ER
S
PM,
(b)
smooth ER
S
Golgi
S
lysosome
S
PM,
(c)
rough ER
S
Golgi
S
PM,
(d)
nucleus
S
Golgi
S
PM.
Short Answer Essay Questions
20.
Which organelle is responsible for a newborn having distinctive
toes and fingers instead of webbed digits?
21.
Explain why mitosis can be thought of as cellular immortality.
22.
Contrast the roles of ER-bound ribosomes with those free in the
cytosol.
23.
Cells lining the trachea have whiplike motile extensions on their
free surfaces. What are these extensions, what is their source, and
what is their function?
24.
Name the three phases of interphase and describe an activity
unique to each phase.
25.
Comment on the role of the sodium-potassium pump in
maintaining a cell’s resting membrane potential.
26.
Differentiate between primary and secondary active transport
processes.
27.
Cell division typically yields two daughter cells, each with one
nucleus. How is the occasional binucleate condition of liver cells
explained?
Review Questions
3
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