PORTAGE BIOD 101 MODULE 6 – COMPLETE
STUDY GUIDE 150 Practice Questions with
Verified Answers & Detailed Rationales
EXAM OVERVIEW
BIOD 101 – Foundations of Biology I Module 6 covers key concepts in microbiology,
immunology, and infectious disease. Topics include prokaryotic cell structure, bacterial
classification, the immune system (innate and adaptive), antibiotic mechanisms, and virulence
factors.
SECTION 1: PROKARYOTIC VS. EUKARYOTIC CELLS
Q1. Discuss the difference in how prokaryotic and eukaryotic cells store their genetic material.
Correct Answer: Eukaryotic cells store their DNA in a membrane-bound nucleus, while
prokaryotic cells store their DNA in a nucleoid region, which is not membrane-bound.
Rationale: The nucleus is a defining feature of eukaryotic cells, providing compartmentalization
for transcription and translation. Prokaryotes lack membrane-bound organelles and instead
have a nucleoid region where the circular chromosome is located.
Q2. List TWO similarities between prokaryotic and eukaryotic cells.
Correct Answer: Both cells have a plasma membrane that acts as a semi-permeable barrier and
contain ribosomes to manufacture proteins necessary for life.
Rationale: Despite their differences, all cells share fundamental features: a plasma membrane
for selective permeability, cytoplasm, and ribosomes for protein synthesis.
Q3. Describe how eukaryotic cells store genetic information.
,Correct Answer: Eukaryotic cells store their DNA in a membrane-bound nucleus.
Rationale: The nuclear envelope separates transcription from translation, allowing for more
complex regulation of gene expression in eukaryotes.
Q4. Describe the role of the cell wall in a bacterial cell.
Correct Answer: The cell wall is responsible for the shape of a cell and provides protection
against environmental stressors.
Rationale: The bacterial cell wall maintains structural integrity, prevents osmotic lysis, and
protects against environmental threats such as antibiotics and host immune factors.
Q5. List THREE accessory structures that facilitate movement and attachment in bacteria.
Correct Answer: Capsule, fimbriae, and flagella.
Rationale: The capsule provides protection and adhesion, fimbriae allow attachment to surfaces
and host cells, and flagella enable motility.
Q6. Compare and contrast Gram-positive and Gram-negative bacteria regarding the amount of
peptidoglycan present in their cell walls.
Correct Answer: Gram-positive bacteria have a thick layer of peptidoglycan, while
Gram-negative bacteria have a thin layer of peptidoglycan.
Rationale: The thickness of the peptidoglycan layer determines the outcome of the Gram-stain
procedure and affects antibiotic susceptibility.
Q7. Describe the Gram-stain process.
Correct Answer: First, a sample of the bacteria is stained with a crystal violet dye and iodine.
Next, the sample is rinsed with alcohol to remove the unbound dyes. Finally, the sample is
stained a second time with a red dye. The properties of the cell wall determine how the dyes
change the color of the cell.
,Rationale: The Gram-stain differentiates bacteria based on cell wall structure. Gram-positive
bacteria retain the purple crystal violet, while Gram-negative bacteria lose it and take up the red
counterstain.
Q8. List and describe the most common bacterial shapes.
Correct Answer:
- Cocci: spherical shape
- Bacilli: rod shape
- Spiral: spiral shape, ranging from a comma to a corkscrew shape
Rationale: Bacterial morphology is a key characteristic used in identification and classification.
Q9. Spherical-shaped cells arranged in chains can be best described as ______.
Correct Answer: Streptococci
Rationale: "Strepto-" indicates chains, while "cocci" indicates spherical shape. Streptococci are
gram-positive cocci arranged in chains.
Q10. Spherical-shaped cells arranged in clusters can be best described as ______.
Correct Answer: Staphylococci
Rationale: "Staphylo-" indicates clusters, while "cocci" indicates spherical shape. Staphylococci
are gram-positive cocci arranged in grape-like clusters.
Q11. Spherical-shaped cells arranged in pairs can be best described as ______.
Correct Answer: Diplococci
Rationale: "Diplo-" indicates pairs, while "cocci" indicates spherical shape. Diplococci include
organisms such as Neisseria and Streptococcus pneumoniae.
, Q12. What is the difference between "staphylo-" and "strepto-" arrangements?
Correct Answer: Staphylo- refers to clusters of cocci, while strepto- refers to chains of cocci.
Rationale: These prefixes describe the arrangement of bacterial cells, which is an important
identifying characteristic.
Q13. What is the composition of the bacterial cell wall?
Correct Answer: The bacterial cell wall is composed of peptidoglycan, which consists of NAG
(N-acetylglucosamine) and NAM (N-acetylmuramic acid) cross-linked by amino acid links.
Rationale: Peptidoglycan provides structural strength and determines the shape of the bacterial
cell.
SECTION 2: BACTERIAL IDENTIFICATION & CLINICAL PATHOGENS
Q14. What is the causative agent of strep throat?
Correct Answer: Streptococcus pyogenes, also known as Group A Streptococcus (GAS) .
Rationale: GAS is a gram-positive coccus arranged in chains, responsible for strep throat and
other infections.
Q15. Describe the characteristics of Group A Streptococcus (GAS).
Correct Answer: GAS is a gram-positive coccus arranged in chains.
Rationale: GAS is responsible for strep throat and can lead to complications such as rheumatic
fever if untreated.
Q16. What is the incubation period for GAS infection?
STUDY GUIDE 150 Practice Questions with
Verified Answers & Detailed Rationales
EXAM OVERVIEW
BIOD 101 – Foundations of Biology I Module 6 covers key concepts in microbiology,
immunology, and infectious disease. Topics include prokaryotic cell structure, bacterial
classification, the immune system (innate and adaptive), antibiotic mechanisms, and virulence
factors.
SECTION 1: PROKARYOTIC VS. EUKARYOTIC CELLS
Q1. Discuss the difference in how prokaryotic and eukaryotic cells store their genetic material.
Correct Answer: Eukaryotic cells store their DNA in a membrane-bound nucleus, while
prokaryotic cells store their DNA in a nucleoid region, which is not membrane-bound.
Rationale: The nucleus is a defining feature of eukaryotic cells, providing compartmentalization
for transcription and translation. Prokaryotes lack membrane-bound organelles and instead
have a nucleoid region where the circular chromosome is located.
Q2. List TWO similarities between prokaryotic and eukaryotic cells.
Correct Answer: Both cells have a plasma membrane that acts as a semi-permeable barrier and
contain ribosomes to manufacture proteins necessary for life.
Rationale: Despite their differences, all cells share fundamental features: a plasma membrane
for selective permeability, cytoplasm, and ribosomes for protein synthesis.
Q3. Describe how eukaryotic cells store genetic information.
,Correct Answer: Eukaryotic cells store their DNA in a membrane-bound nucleus.
Rationale: The nuclear envelope separates transcription from translation, allowing for more
complex regulation of gene expression in eukaryotes.
Q4. Describe the role of the cell wall in a bacterial cell.
Correct Answer: The cell wall is responsible for the shape of a cell and provides protection
against environmental stressors.
Rationale: The bacterial cell wall maintains structural integrity, prevents osmotic lysis, and
protects against environmental threats such as antibiotics and host immune factors.
Q5. List THREE accessory structures that facilitate movement and attachment in bacteria.
Correct Answer: Capsule, fimbriae, and flagella.
Rationale: The capsule provides protection and adhesion, fimbriae allow attachment to surfaces
and host cells, and flagella enable motility.
Q6. Compare and contrast Gram-positive and Gram-negative bacteria regarding the amount of
peptidoglycan present in their cell walls.
Correct Answer: Gram-positive bacteria have a thick layer of peptidoglycan, while
Gram-negative bacteria have a thin layer of peptidoglycan.
Rationale: The thickness of the peptidoglycan layer determines the outcome of the Gram-stain
procedure and affects antibiotic susceptibility.
Q7. Describe the Gram-stain process.
Correct Answer: First, a sample of the bacteria is stained with a crystal violet dye and iodine.
Next, the sample is rinsed with alcohol to remove the unbound dyes. Finally, the sample is
stained a second time with a red dye. The properties of the cell wall determine how the dyes
change the color of the cell.
,Rationale: The Gram-stain differentiates bacteria based on cell wall structure. Gram-positive
bacteria retain the purple crystal violet, while Gram-negative bacteria lose it and take up the red
counterstain.
Q8. List and describe the most common bacterial shapes.
Correct Answer:
- Cocci: spherical shape
- Bacilli: rod shape
- Spiral: spiral shape, ranging from a comma to a corkscrew shape
Rationale: Bacterial morphology is a key characteristic used in identification and classification.
Q9. Spherical-shaped cells arranged in chains can be best described as ______.
Correct Answer: Streptococci
Rationale: "Strepto-" indicates chains, while "cocci" indicates spherical shape. Streptococci are
gram-positive cocci arranged in chains.
Q10. Spherical-shaped cells arranged in clusters can be best described as ______.
Correct Answer: Staphylococci
Rationale: "Staphylo-" indicates clusters, while "cocci" indicates spherical shape. Staphylococci
are gram-positive cocci arranged in grape-like clusters.
Q11. Spherical-shaped cells arranged in pairs can be best described as ______.
Correct Answer: Diplococci
Rationale: "Diplo-" indicates pairs, while "cocci" indicates spherical shape. Diplococci include
organisms such as Neisseria and Streptococcus pneumoniae.
, Q12. What is the difference between "staphylo-" and "strepto-" arrangements?
Correct Answer: Staphylo- refers to clusters of cocci, while strepto- refers to chains of cocci.
Rationale: These prefixes describe the arrangement of bacterial cells, which is an important
identifying characteristic.
Q13. What is the composition of the bacterial cell wall?
Correct Answer: The bacterial cell wall is composed of peptidoglycan, which consists of NAG
(N-acetylglucosamine) and NAM (N-acetylmuramic acid) cross-linked by amino acid links.
Rationale: Peptidoglycan provides structural strength and determines the shape of the bacterial
cell.
SECTION 2: BACTERIAL IDENTIFICATION & CLINICAL PATHOGENS
Q14. What is the causative agent of strep throat?
Correct Answer: Streptococcus pyogenes, also known as Group A Streptococcus (GAS) .
Rationale: GAS is a gram-positive coccus arranged in chains, responsible for strep throat and
other infections.
Q15. Describe the characteristics of Group A Streptococcus (GAS).
Correct Answer: GAS is a gram-positive coccus arranged in chains.
Rationale: GAS is responsible for strep throat and can lead to complications such as rheumatic
fever if untreated.
Q16. What is the incubation period for GAS infection?
