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Chapter 1: Cellular Biology
MULTIPLE CHOICE
1. Which statement best describes the cellular function of metabolic absorption?
a. Cells can produce proteins. c. Cells can take in and use nutrients.
b. Cells can secrete digestive enzymes. d. Cells can synthesize fats.
ANS: C
In metabolic absorption, all cells take in and use nutrients and other substances from their
surroundings. The remaining options are not inclusive in their descriptions of cellular metabolic
absorption.
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2. Most of a cell’s genetic information, including RNA and DNA, is contained in the:
a. Mitochondria c. Nucleolus
b. Ribosome d. Lysosome
ANS: C
The nucleus contains the nucleolus, a small dense structure composed largely of RNA, most of
the cellular DNA, and the DNA-binding proteins, such as the histones, which regulate its activity.
The other options do not contain most of a cell’s genetic information.
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3. Which component of the cell prodNuU
ceRsSIhNyGdrToBg.CenOpMeroxide (H2O2) by using oxygen to remove
hydrogen atoms from specific substrates in an oxidative reaction?
a. Lysosomes c. Ribosomes
b. Peroxisomes d. Oxyhydrosomes
ANS: B
Peroxisomes are so named because they usually contain enzymes that use oxygen to remove
hydrogen atoms from specific substrates in an oxidative reaction that produces H2O2, which is a
powerful oxidant and potentially destructive if it accumulates or escapes from peroxisomes.
Ribosomes are RNA-protein complexes (nucleoproteins) that are synthesized in the nucleolus and
secreted into the cytoplasm through pores in the nuclear envelope called nuclear pore complexes.
Lysosomes are saclike structures that originate from the Golgi complex and contain more than 40
digestive enzymes called hydrolases, which catalyze bonds in proteins, lipids, nucleic acids, and
carbohydrates. Oxyhydrosomesare involved in enzyme production.
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4. Which cell component is capable of cellular autodigestion when it is released during cellinjury?
a. Ribosome c. Smooth endoplasmic reticulum
b. Golgi complex d. Lysosomes
ANS: D
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The lysosomal membrane acts as a protective shield between the powerful digestive enzymes
within the lysosome and the cytoplasm, preventing their leakage into the cytoplasmic matrix.
Disruption of the membrane by various treatments or cellular injury leads to a release of the
lysosomal enzymes, which can then react with their specific substrates, causing cellular self-
digestion. The other options do not correctly describe thisprocess.
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5. What is the sequence of steps in the development of a digestive enzyme by the pancreas cells
from the initial transcription to the release from the cell?
a. The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the
ribosome for synthesis, and is transported in a secretory vesicle to the cell
membrane.
b. The enzyme is transcribed from RNA by DNA in the nucleus, proceeds to the lysosome for
synthesis, and is transported in an encapsulated membrane to the cellmembrane.
c. The enzyme is transcribed by the mitochondria in the nucleus, proceeds to the ribosome
for synthesis, and is transported in a cytoskeleton to the cell membrane.
d. The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the Golgi
complex for synthesis, and is transported in a cytosol to the cell membrane.
ANS: A
The enzyme is transcribed from DNA by RNA in the nucleus, proceeds to the ribosomefor
synthesis, and is transported in a secretory vesicle to the cell membrane. The other options do
not correctly describe this process.
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6. During which phase of the cell cycle is DNA synthesized?
a. G1 c. G2
b. S d. M
ANS: B
The four designated phases of the cell cycle are: (1) the G1 phase (G = gap), which is the period
between the M phase (M = mitosis) and the start of DNA synthesis; (2) the S phase(S = synthesis),
during which DNA is synthesized in the cell nucleus; (3) the G2 phase, during which RNA and
protein synthesis occurs, the period between the completion of DNA synthesis and the next phase
(M); and (4) the M phase, which includes nuclear and cytoplasmic division.
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7. What organic compound facilitates transportation across cell membranes by acting as
receptors, transport channels for electrolytes, and enzymes to drive active pumps?
a. Lipids c. Proteins
b. Proteases d. Carbohydrates
ANS: C
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Proteins act as (1) recognition and binding units (receptors) for substances moving in andout of the
cell; (2) pores or transport channels for various electrically charged particles called ions or
electrolytes and specific carriers for amino acids and monosaccharides; and
(3) specific enzymes that drive active pumps that promote the concentration of certain ions,
particularly potassium (K+), within the cell while keeping concentrations of otherions, for example,
sodium (Na+), below the concentrations found in the extracellular environment. The other options
do not correctly describe this process.
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8. Understanding the various steps of proteolytic cascades, such as caspase-mediated apoptosis
and complement cascades, may be useful in designing drug therapy for whichhuman diseases?
a. Cardiac and vascular disorders
b. Autoimmune and malignant disorders
c. Gastrointestinal and renal disorders
d. Endocrine and gastrointestinal disorders
ANS: B
Understanding the various steps involved in this process is crucial for designing drug
interventions. Dysregulation of proteases features prominently in many human diseases,including
cancer, autoimmunity, and neurodegenerative disorders. The other options do not correctly
describe this process.
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9. Which structure prevents water-soluble molecules from entering cells across the plasma
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membrane?
a. Carbohydrate chains c. Membrane channel proteins
b. Glycoprotein channels d. Lipid bilayer
ANS: D
The bilayer’s structure accounts for one of the essential functions of the plasma membrane. It is
impermeable to most water-soluble molecules (molecules that dissolve inwater) because the water-
soluble molecules are insoluble in the oily core region. The bilayer serves as a barrier to the
diffusion of water and hydrophilic substances while allowing lipid-soluble molecules, such as
oxygen (O2) and carbon dioxide (CO2), to diffuse through it readily. The other options do not
correctly describe this process.
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10. The fluid mosaic model explains:
a. How a cell membrane functions
b. Why our bodies appear to be solid
c. How tissue is differentiated
d. How fluid moves between the intracellular and extracellular compartments
ANS: A
The fluid mosaic model accounts for the flexibility of cellular membranes, their
self-sealing properties, and their impermeability to many substances. The remainingoptions do not
explain the mosaic model.
