Chapter 1: Cellular Biology
MULTIPLE CHOICE
1. Which statement best describes the cellular function of metabolic absorption?
a.
Cells can produce proteins.
b.
Cells can secrete digestive enzymes.
c.
Cells can take in and use nutrients.
d.
Cells can synthesize fats. - correct answers 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.
2. Most of a cell's genetic information, including RNA and DNA, is contained in the:
a.
Mitochondria
b.
Ribosome
c.
Nucleolus
d.
,Lysosome - correct answersANS: 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.
3. Which component of the cell produces hydrogen peroxide (H2O2) by using oxygen to remove
hydrogen atoms from specific substrates in an oxidative reaction?
a.
Lysosomes
b.
Peroxisomes
c.
Ribosomes
d.
Oxyhydrosomes - correct answersANS: 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. Oxyhydrosomes are involved
in enzyme production.
4. Which cell component is capable of cellular autodigestion when it is released during cell injury?
a. Ribosome
, b. Golgi complex
c. Smooth endoplasmic reticulum
d. Lysosomes - correct answersANS: D
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 this process.
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
b.
Proteases
c.
Proteins
d.
Carbohydrates - correct answersANS: C
Proteins act as (1) recognition and binding units (receptors) for substances moving in and out 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 other ions, for example, sodium (Na+), below the concentrations found in the
extracellular environment. The other options do not correctly describe this process.
9. Which structure prevents water-soluble molecules from entering cells across the plasma membrane?
a.
Carbohydrate chains
b.