BIOD 171 General Biology 1 Final Exam
Review-Portage Learning | All Questions And
Solutions (Rationales) | Exam Prep Q&A
2026/2027
Which of the following cellular structures is present in both prokaryotic and eukaryotic
organisms and serves as the primary site of protein synthesis using mRNA templates?
A. Nucleolus
B. Ribosome
C. Endoplasmic reticulum
D. Golgi apparatus
Rationale: Ribosomes are non-membrane-bound complexes composed of ribosomal RNA and
proteins that carry out translation in all living cells, including prokaryotes and eukaryotes.
Nuclei, ER, and Golgi apparatus are membrane-bound organelles restricted to eukaryotic
cells.
A researcher isolates an unknown single-celled microorganism from an aquatic sample.
Structural analysis reveals a peptidoglycan cell wall, a single circular chromosome, and no
membrane-bound organelles. How should this organism be classified?
A. Domain Eukarya
B. Domain Archaea
C. Domain Bacteria
D. Acellular virus
Rationale: Domain Bacteria is characterized by peptidoglycan cell walls and prokaryotic cell
organization lacking membrane-bound organelles and a true nucleus. Archaea lack
peptidoglycan in their cell walls, and Eukarya possess membrane-bound organelles.
During dark-field microscopy, how is the light path arranged to view unstained,
transparent biological specimens?
A. Light passes directly through the specimen into the objective lens.
,B. Light is absorbed by fluorescent dye markers bound to cellular structures.
C. Light hits the specimen at an angle, and only scattered light enters the objective lens.
D. Ultraviolet light is reflected off a metallic coating applied to the specimen surface.
Rationale: Dark-field microscopy utilizes a specialized condenser stop that blocks direct light,
directing light at an angle toward the specimen. Only light scattered by the specimen enters
the objective, resulting in a bright image against a dark background.
A laboratory technician performs a Gram stain on a bacterial sample. After completing the
decolorization step with alcohol, what is the state of Gram-negative bacterial cells?
A. Purple due to retained crystal violet-iodine complexes
B. Colorless due to lipid extraction and increased outer membrane permeability
C. Pink due to immediate safranin uptake
D. Green due to malachite green retention
Rationale: Alcohol dissolves the lipid-rich outer membrane of Gram-negative bacteria and
creates large pores in the thin peptidoglycan layer, washing out the crystal violet-iodine
complex and leaving the cells temporarily colorless until counterstained.
Which macromolecule is formed through condensation reactions linking amino acid
monomers via covalent peptide bonds?
A. Polysaccharide
B. Nucleic acid
C. Triglyceride
D. Polypeptide
Rationale: Amino acids undergo dehydration synthesis (condensation reactions) to form
covalent peptide bonds between the carboxyl group of one amino acid and the amino group
of another, constructing polypeptides.
An enzyme activity assay shows a sharp decline in catalytic rate when the ambient
temperature exceeds 60°C. What molecular mechanism primary accounts for this observed
loss of function?
A. Disruption of non-covalent interactions leading to tertiary structure denaturation
,B. Cleavage of primary covalent peptide bonds along the backbone
C. Hydrolysis of substrate molecules before active site binding
D. Irreversible conversion of the enzyme into an lipid subunit
Rationale: High temperatures disrupt delicate non-covalent interactions (hydrogen bonds,
ionic bonds, hydrophobic interactions) that stabilize an enzyme's functional three-dimensional
tertiary structure, causing denaturation and loss of catalytic activity.
In cellular respiration, which metabolic pathway occurs in the cytoplasm and yields a net
product of 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose molecule?
A. Citric Acid Cycle
B. Glycolysis
C. Oxidative Phosphorylation
D. Electron Transport Chain
Rationale: Glycolysis is an anaerobic pathway taking place in the cytoplasm that breaks down
one 6-carbon glucose molecule into two 3-carbon pyruvate molecules, generating a net gain
of 2 ATP and 2 NADH.
Under anaerobic conditions in human skeletal muscle tissue, pyruvate produced by
glycolysis is directly reduced to which metabolite to regenerate NAD+?
A. Ethanol
B. Acetyl-CoA
C. Lactate
D. Oxaloacetate
Rationale: When oxygen is limited, muscle cells undergo lactic acid fermentation where
lactate dehydrogenase converts pyruvate to lactate, oxidizing NADH back to NAD+ to allow
continued glycolytic ATP production.
Which cellular organelle contains acid hydrolase enzymes and functions as the primary site
for intracellular digestion and organelle recycling (autophagy)?
A. Peroxisome
, B. Lysosome
C. Glyoxysome
D. Vacuole
Rationale: Lysosomes contain digestive acid hydrolases maintained at acidic pH, responsible
for degrading macromolecules, engulfed cellular debris, and damaged organelles through
autophagy.
What physical property of water molecules allows them to form hydrogen bonds with each
other and act as an exceptional biological solvent for polar solutes?
A. Low heat capacity
B. Non-polar covalent bonding
C. Polarity caused by unequal electron sharing between oxygen and hydrogen
D. High volatility at room temperature
Rationale: Oxygen's high electronegativity relative to hydrogen creates a polar molecule with
partial negative charges on oxygen and partial positive charges on hydrogen, enabling
hydrogen bonding and attraction to polar solutes.
Which of the following optical microscopy techniques uses high-intensity ultraviolet or
LED light to excite fluorophores attached to target cellular components?
A. Phase-contrast microscopy
B. Bright-field microscopy
C. Fluorescence microscopy
D. Transmission electron microscopy
Rationale: Fluorescence microscopy exposes specimens labeled with fluorophores to light of a
specific short excitation wavelength (such as UV or blue light), causing the fluorophore to
emit light at a longer wavelength.
A clinical isolate is identified as a spore-forming Gram-positive rod capable of surviving
extreme heat, chemical disinfection, and desiccation. Which bacterial structure accounts
for this resistance?
A. Capsule
Review-Portage Learning | All Questions And
Solutions (Rationales) | Exam Prep Q&A
2026/2027
Which of the following cellular structures is present in both prokaryotic and eukaryotic
organisms and serves as the primary site of protein synthesis using mRNA templates?
A. Nucleolus
B. Ribosome
C. Endoplasmic reticulum
D. Golgi apparatus
Rationale: Ribosomes are non-membrane-bound complexes composed of ribosomal RNA and
proteins that carry out translation in all living cells, including prokaryotes and eukaryotes.
Nuclei, ER, and Golgi apparatus are membrane-bound organelles restricted to eukaryotic
cells.
A researcher isolates an unknown single-celled microorganism from an aquatic sample.
Structural analysis reveals a peptidoglycan cell wall, a single circular chromosome, and no
membrane-bound organelles. How should this organism be classified?
A. Domain Eukarya
B. Domain Archaea
C. Domain Bacteria
D. Acellular virus
Rationale: Domain Bacteria is characterized by peptidoglycan cell walls and prokaryotic cell
organization lacking membrane-bound organelles and a true nucleus. Archaea lack
peptidoglycan in their cell walls, and Eukarya possess membrane-bound organelles.
During dark-field microscopy, how is the light path arranged to view unstained,
transparent biological specimens?
A. Light passes directly through the specimen into the objective lens.
,B. Light is absorbed by fluorescent dye markers bound to cellular structures.
C. Light hits the specimen at an angle, and only scattered light enters the objective lens.
D. Ultraviolet light is reflected off a metallic coating applied to the specimen surface.
Rationale: Dark-field microscopy utilizes a specialized condenser stop that blocks direct light,
directing light at an angle toward the specimen. Only light scattered by the specimen enters
the objective, resulting in a bright image against a dark background.
A laboratory technician performs a Gram stain on a bacterial sample. After completing the
decolorization step with alcohol, what is the state of Gram-negative bacterial cells?
A. Purple due to retained crystal violet-iodine complexes
B. Colorless due to lipid extraction and increased outer membrane permeability
C. Pink due to immediate safranin uptake
D. Green due to malachite green retention
Rationale: Alcohol dissolves the lipid-rich outer membrane of Gram-negative bacteria and
creates large pores in the thin peptidoglycan layer, washing out the crystal violet-iodine
complex and leaving the cells temporarily colorless until counterstained.
Which macromolecule is formed through condensation reactions linking amino acid
monomers via covalent peptide bonds?
A. Polysaccharide
B. Nucleic acid
C. Triglyceride
D. Polypeptide
Rationale: Amino acids undergo dehydration synthesis (condensation reactions) to form
covalent peptide bonds between the carboxyl group of one amino acid and the amino group
of another, constructing polypeptides.
An enzyme activity assay shows a sharp decline in catalytic rate when the ambient
temperature exceeds 60°C. What molecular mechanism primary accounts for this observed
loss of function?
A. Disruption of non-covalent interactions leading to tertiary structure denaturation
,B. Cleavage of primary covalent peptide bonds along the backbone
C. Hydrolysis of substrate molecules before active site binding
D. Irreversible conversion of the enzyme into an lipid subunit
Rationale: High temperatures disrupt delicate non-covalent interactions (hydrogen bonds,
ionic bonds, hydrophobic interactions) that stabilize an enzyme's functional three-dimensional
tertiary structure, causing denaturation and loss of catalytic activity.
In cellular respiration, which metabolic pathway occurs in the cytoplasm and yields a net
product of 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose molecule?
A. Citric Acid Cycle
B. Glycolysis
C. Oxidative Phosphorylation
D. Electron Transport Chain
Rationale: Glycolysis is an anaerobic pathway taking place in the cytoplasm that breaks down
one 6-carbon glucose molecule into two 3-carbon pyruvate molecules, generating a net gain
of 2 ATP and 2 NADH.
Under anaerobic conditions in human skeletal muscle tissue, pyruvate produced by
glycolysis is directly reduced to which metabolite to regenerate NAD+?
A. Ethanol
B. Acetyl-CoA
C. Lactate
D. Oxaloacetate
Rationale: When oxygen is limited, muscle cells undergo lactic acid fermentation where
lactate dehydrogenase converts pyruvate to lactate, oxidizing NADH back to NAD+ to allow
continued glycolytic ATP production.
Which cellular organelle contains acid hydrolase enzymes and functions as the primary site
for intracellular digestion and organelle recycling (autophagy)?
A. Peroxisome
, B. Lysosome
C. Glyoxysome
D. Vacuole
Rationale: Lysosomes contain digestive acid hydrolases maintained at acidic pH, responsible
for degrading macromolecules, engulfed cellular debris, and damaged organelles through
autophagy.
What physical property of water molecules allows them to form hydrogen bonds with each
other and act as an exceptional biological solvent for polar solutes?
A. Low heat capacity
B. Non-polar covalent bonding
C. Polarity caused by unequal electron sharing between oxygen and hydrogen
D. High volatility at room temperature
Rationale: Oxygen's high electronegativity relative to hydrogen creates a polar molecule with
partial negative charges on oxygen and partial positive charges on hydrogen, enabling
hydrogen bonding and attraction to polar solutes.
Which of the following optical microscopy techniques uses high-intensity ultraviolet or
LED light to excite fluorophores attached to target cellular components?
A. Phase-contrast microscopy
B. Bright-field microscopy
C. Fluorescence microscopy
D. Transmission electron microscopy
Rationale: Fluorescence microscopy exposes specimens labeled with fluorophores to light of a
specific short excitation wavelength (such as UV or blue light), causing the fluorophore to
emit light at a longer wavelength.
A clinical isolate is identified as a spore-forming Gram-positive rod capable of surviving
extreme heat, chemical disinfection, and desiccation. Which bacterial structure accounts
for this resistance?
A. Capsule
