TEST BANK
Test Bank for Porth's Essentials of Pathophysiology
5th edition
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TEST BANK
, Tommie L. Norris: Porth's Essentials of Pathophysiology
Chapter 1: Cell Structure and Function
MULTIPLE CHOICE
1. Although the basic structure of the cell plasma membrane is formed by a lipid bilayer,
most ofthe specific membrane functions are carried out by:
A) Bound and transmembrane proteins
B) Complex, long carbohydrate chains
C) Surface antigens and hormone receptors
D) A gating system of selective ion channels
Ans: A
Feedback:
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The functions of plasma membrane depend on the presence of proteins that are bound in the lipid
bilayer and some that have the ability to pass freely into and out of the cell.
Carbohydrate chains form a cell coat that surrounds the membrane and that contain surface
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antigens and surface hormone receptors. Some ion channels are gated and open only when the
membrane potential changes significantly.
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1. Which describes the function of the nucleus?
A) It is basically the site of protein synthesis in the body.
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B) It contains the genetic code for the individual.
C) It is the transformer of cellular energy.
D) It initiates the process of aerobic metabolism.
Ans: B
Feedback:
The nucleus contains DNA, which contains the genetic code that contains the information that
controls cells. Ribosomes synthesize protein. Mitochondria transform organic compounds into
cellular energy. Mitochondria require oxygen for aerobic metabolism, using hydrogen and
carbon combined with oxygen molecules to form carbon dioxide and water as energy is released.
2. Which of the following aspects of the function of the nucleus is performed by ribosomal
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, RNA (rRNA)?
A) Copying and carrying DNA instructions for protein synthesis
B) Carrying amino acids to the site of protein synthesis
C) Providing the site where protein synthesis occurs
D) Regulating and controlling protein synthesis
Ans: C
Feedback:
There are three types of ribonucleic acid (messenger RNA, ribosomal RNA, and transfer RNA)
that move to the cytoplasm and carry out the actual synthesis of proteins.
Messenger RNA (mRNA) copies and carries the DNA instructions for protein synthesis to the
cytoplasm; ribosomal RNA (rRNA) is the site of protein synthesis; and transfer RNA (tRNA)
transports amino acids to the site of protein synthesis for incorporation into the protein being
synthesized.
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3. Which accurately explains the functions of the organelles lysosomes? They:
A) Are sacs filled with enzymes that breakdown and remove foreign substances and worn-
out cell parts
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B) Function in association with the endoplasmic reticulum to modify protein end products
and package them into secretory granules or vesicles
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C) Are small particles of nucleoproteins that are involved in the synthesis of proteins that
remain in the cell as cytoplasmic structural or functional elements
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D) Are a dynamic system of interconnected membranous tubes that functions as a tubular
communication system for transporting various substances from one part of the cell to another
Ans: A
Feedback:
Lysosomes are sacs that are filled with hydrolytic enzymes that aid in the processing and
removal of unwanted substances within the cytoplasm. The Golgi apparatus functions in
association with the endoplasmic reticulum to modify and package substances in preparation for
secretion, whereas ribosomes are small particles of nucleoproteins that are involved in the
synthesis of proteins. The ER is a tubular communication system for transporting various
substances from one part of the cell to another.
4. Impairment in the function of peroxisomes would result in:
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, A) Inadequate sites for protein synthesis
B) An inability to transport cellular products across the cell membrane
C) Insufficient energy production within a cell
D) Accumulation of free radicals in the cytoplasm
Ans: D
Feedback:
Peroxisomes function in the control of free radicals; unless degraded, these highly unstable
chemical compounds damage other cytoplasmic molecules. Peroxisomes do not directly
contribute to energy production, protein synthesis, or transport of cellular secretions.
5. Although energy is not made in mitochondria, they are known as the “power plants” of
the cell because they:
A) Contain RNA for protein synthesis
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B) Utilize glycolysis for oxidative energy
C) Extract energy from organic compounds
D) Store calcium bonds for muscle contractions
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Ans: C
Feedback:
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Mitochondria contain the enzymes needed for transforming organic compounds into energy that
is easily accessible to the cell. Mitochondria contain their own DNA. Glycolysis is anaerobic
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metabolism and unrelated to oxidative energy. Mitochondria store phosphate bonds (such as in
ATP) to power cellular functions.
6. Semen analysis indicates that the client's sperm have decreased motility. Which of the
following cellular components may be defective within the client's sperm?
A) Ribosomes
B) Microtubules
C) Mitochondria
D) Microfilaments
Ans: B
Feedback:
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, Abnormalities in the structure and function of microtubules and consequent dysfunction of the
flagella may contribute to impaired sperm motility. Ribosomes, microfilaments, and
mitochondria do not directly contribute to movement in cells such as cilia and flagella.
7. When explaining the function of glycolysis as it relates to anaerobic metabolism, the
faculty will mention which of the following key points? Select all that apply.
A) Glycolysis requires the use of oxygen to begin the process.
B) Glycolysis occurs in mitochondrion-lacking cells.
C) Glycolysis provides the majority of the body's energy needs.
D) Pyruvic acid is an end result from a series of reactions that converts glucose.
Ans: B, D
Feedback:
Glycolysis is the anaerobic process by which energy is liberated from glucose, and it is an
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important source of energy for cells that lack mitochondria. The process also provides a
temporary source of energy for cells that are deprived of an adequate supply of oxygen.
Glycolysis involves a sequence of reactions that converts glucose to pyruvic acid, with the
concomitant production of ATP from ADP. It accounts for a small minority of the body's energy
needs and results in NADH, hydrogen ions, ATP, and pyruvic acid.
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8. Aerobic metabolism, also known as oxidative metabolism, provides energy to the body
by:
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A) Removing the phosphate bonds from ATP
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B) Combining hydrogen and oxygen to form water
C) Activating pyruvate stored in the cytoplasm
D) Breaking down glucose to form lactic acid
Ans: B
Feedback:
Aerobic metabolism involves the combination of carbon ions from dietary nutrients, hydrogen
ions, and oxygen. The result is carbon dioxide and water as energy is released, which is stored in
ATP. Phosphate bonds are added (not removed from) to ADP to form ATP. Pyruvate is
formedfrom glucose in the anaerobic process of glycolysis and is converted to lactic acid
during anaerobic metabolism.
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, 9. To effectively relay signals, cell-to-cell communication utilizes a chemical messenger
system to:
A) Displace surface receptor proteins
B) Accumulate within cell gap junctions
C) Bind to contractile microfilaments
D) Release secretions into extracellular fluid
Ans: D
Feedback:
Signals are transmitted by releasing chemical secretions into extracellular fluid. Chemical signals
move through cell-to-cell junctions to reach other cells and may attach to surface receptor
proteins. The cytoplasmic contractile microfilaments are incapable of transmitting
communication signals.
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10. Which identifies correctly how the G protein–linked receptors are similar?
A) Their cytosolic domain has intrinsic enzyme activity.
B) Insulin is an example of the second messenger cAMP, which binds to an enzyme-linked
receptor.
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C) These linked receptors are involved in rapid synaptic signaling between cardiac electrical
cells.
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D) They have a ligand-binding extracellular receptor component, which causes changes that
activate the G protein on the cytoplasmic side of the cell membrane.
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Ans: D
Feedback:
Although there are differences among the G protein–linked receptors, all share a number of
features. They all have a ligand-binding extracellular receptor component, which recognizes a
specific ligand or first messenger. Upon ligand binding, they all undergo conformational changes
that activate the G protein found on the cytoplasmic side of the cell membrane. Instead of having
a cytosolic domain that associates with a G protein, enzyme-linked receptors have cytosolic
domain either that has intrinsic enzyme activity or that associates directly with an enzyme. The
binding of the hormone to a special transmembrane receptor results in activation of the enzyme
adenylyl cyclase at the intracellular portion of the receptor. This enzyme then catalyzes the
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, formation of the second messenger cAMP, which has multiple effects on cell function. Insulin,
for example, acts by binding to an enzyme-linked receptor. Ion channel–linked receptors are
involved in the rapid synaptic signaling between electrically excitable cells.
11. When working with a client who has end-stage renal disease (ESRD) and is receiving
peritoneal dialysis, the concept of diffusion can be explained by which of the following
statements?
A) “If your potassium level is high, then K+ particles will move from your peritoneal cavity
into the dialysis solution, where the concentration of K+ is lower.”
B) “You will need to give yourself a potent diuretic so that you can pull the potassium into
your blood stream and filter the potassium out in your kidneys.”
C) “Your potassium molecules are lipid soluble and will dissolve in the lipid matrix of your
cell membranes.”
D) “If you can get very warm in a sauna, you will heat up your K+ particles, and the kinetic
movement of the particles will increase and pass through the cell membranes faster.”
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Ans: A
Feedback:
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Diffusion refers to the passive process by which molecules and other particles in a solution
become widely dispersed and reach a uniform concentration because of energy created by their
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spontaneous kinetic movements. In the process of reaching a uniform concentration, these
molecules and particles move “downhill” from an area of higher to an area of lower
concentration. Lipid-soluble molecules, such as oxygen, carbon dioxide, alcohol, and fatty acids
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(not K+), become dissolved in the lipid matrix of the cell membrane and diffuse through the
membrane in the same manner that diffusion occurs in water. Diuretics are not very effective if a
person has ESRD. The rate of diffusion depends on how many particles are available for
diffusion, the kinetic movement of the particles, and the number and size of the openings in the
membrane through which the molecules or ions can move. The environmental temperature does
not play a role in this.
12. A male client with a diagnosis of type 1 diabetes mellitus is experiencing
hyperglycemiabecause he lacks sufficient insulin to increase the availability of glucose
transporters in his cell membranes. Consequently, his cells lack intracellular glucose, and it
accumulates in his blood. Which of the following processes would best allow glucose to cross
his cell membranes?
A) Facilitated diffusion
B) Simple diffusion
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, C) Secondary active transport
D) Endocytosis
Ans: A Feedback:
Transport molecules perform facilitated diffusion, in which one substance carries another
substance across a cell membrane. Simple diffusion does not require a transport molecule.
Glucose does not cross the cell membrane by secondary active transport or endocytosis.
13. The client asks the health care provider to explain phagocytosis. The provider will
respond, “Phagocytosis:
A) Is a cotransport system that helps with the absorption of the medication.”
B) Is the movement of particles from an area of higher concentration to one of lower
concentration.”
C) Uses proteins to form an open channel through which the drug can move into the cell.”
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D) Is a process where microorganisms are engulfed and subsequently degraded or killed.”
Ans: D
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Feedback:
Phagocytosis, which means “cell eating,” involves the engulfment and subsequent killing or
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degradation of microorganisms and other particulate matter. Certain cells, such as macrophages
and neutrophils, are adept at engulfing and disposing of invading organisms, damaged cells, and
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unneeded extracellular constituents. An example of cotransport occurs in the intestine, where the
absorption of glucose and amino acids is coupled with sodium transport. The process of diffusion
describes particle movement from an area of higher concentration to an area of lower
concentration, resulting in an equal distribution of permeable substances across the cell
membrane. Ion channels are integral proteins that span the width of the membrane and are
normally composed of several polypeptides or protein subunits that form a gating system.
Specific stimuli cause the protein subunits to undergo conformational changes to form an
openchannel or gate through which the ions can move.
14. Exocytosis allows granular content to be released into extracellular fluid by:
A) Engulfing and ingesting fluid and proteins for transport
B) Killing, degrading, and dissolving harmful microorganisms
C) Removing cellular debris and releasing synthesized substances like hormones
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