MICROBIOLOGY – EXAM LATEST 2026 UPDATE 100
QUESTIONS AND DETAILED VERIFIED ANSWERS
FROM ACTUAL EXAMS TEST GRADE A+
1. Which structure is found in all bacteria?
A. Nucleus
B. Mitochondria
C. Ribosomes
D. Chloroplast
Rationale: All bacteria must have ribosomes for protein synthesis, while other
organelles are absent in prokaryotes.
Answer: C. Ribosomes
2. The Gram stain differentiates bacteria based on:
A. DNA sequence
B. Cell wall composition
C. Capsule presence
D. Flagella type
Rationale: Gram-positive and Gram-negative bacteria differ in peptidoglycan
thickness.
Answer: B. Cell wall composition
3. Which bacteria are stained purple after Gram staining?
A. Gram-negative
B. Acid-fast
C. Gram-positive
D. Mycoplasma
,Rationale: Gram-positive bacteria retain crystal violet dye due to thick
peptidoglycan.
Answer: C. Gram-positive
4. The function of bacterial capsule is to:
A. Aid movement
B. Increase virulence and prevent phagocytosis
C. Produce energy
D. Synthesize proteins
Rationale: Capsules help bacteria evade immune system attack.
Answer: B. Increase virulence and prevent phagocytosis
5. Which structure allows bacterial movement?
A. Pili
B. Flagella
C. Ribosome
D. Plasmid
Rationale: Flagella are locomotory organelles in bacteria.
Answer: B. Flagella
6. Bacterial DNA is usually found in the:
A. Nucleus
B. Nucleoid
C. Cytoplasm membrane
D. Ribosome
Rationale: Prokaryotes lack a true nucleus; DNA is in nucleoid region.
Answer: B. Nucleoid
, 7. Which stain is used to detect Mycobacterium tuberculosis?
A. Gram stain
B. India ink
C. Acid-fast stain
D. Capsule stain
Rationale: Mycobacteria have mycolic acid in their cell wall requiring acid-fast
staining.
Answer: C. Acid-fast stain
8. Viral genetic material may be:
A. Only DNA
B. Only RNA
C. Either DNA or RNA
D. Protein only
Rationale: Viruses contain either DNA or RNA, not both.
Answer: C. Either DNA or RNA
9. The main purpose of sterilization is to:
A. Reduce microbial load
B. Kill all microorganisms including spores
C. Remove dirt
D. Inhibit growth temporarily
Rationale: Sterilization eliminates all forms of microbial life.
Answer: B. Kill all microorganisms including spores
10. Antibiotics are most effective against:
A. Viruses
B. Fungi only
QUESTIONS AND DETAILED VERIFIED ANSWERS
FROM ACTUAL EXAMS TEST GRADE A+
1. Which structure is found in all bacteria?
A. Nucleus
B. Mitochondria
C. Ribosomes
D. Chloroplast
Rationale: All bacteria must have ribosomes for protein synthesis, while other
organelles are absent in prokaryotes.
Answer: C. Ribosomes
2. The Gram stain differentiates bacteria based on:
A. DNA sequence
B. Cell wall composition
C. Capsule presence
D. Flagella type
Rationale: Gram-positive and Gram-negative bacteria differ in peptidoglycan
thickness.
Answer: B. Cell wall composition
3. Which bacteria are stained purple after Gram staining?
A. Gram-negative
B. Acid-fast
C. Gram-positive
D. Mycoplasma
,Rationale: Gram-positive bacteria retain crystal violet dye due to thick
peptidoglycan.
Answer: C. Gram-positive
4. The function of bacterial capsule is to:
A. Aid movement
B. Increase virulence and prevent phagocytosis
C. Produce energy
D. Synthesize proteins
Rationale: Capsules help bacteria evade immune system attack.
Answer: B. Increase virulence and prevent phagocytosis
5. Which structure allows bacterial movement?
A. Pili
B. Flagella
C. Ribosome
D. Plasmid
Rationale: Flagella are locomotory organelles in bacteria.
Answer: B. Flagella
6. Bacterial DNA is usually found in the:
A. Nucleus
B. Nucleoid
C. Cytoplasm membrane
D. Ribosome
Rationale: Prokaryotes lack a true nucleus; DNA is in nucleoid region.
Answer: B. Nucleoid
, 7. Which stain is used to detect Mycobacterium tuberculosis?
A. Gram stain
B. India ink
C. Acid-fast stain
D. Capsule stain
Rationale: Mycobacteria have mycolic acid in their cell wall requiring acid-fast
staining.
Answer: C. Acid-fast stain
8. Viral genetic material may be:
A. Only DNA
B. Only RNA
C. Either DNA or RNA
D. Protein only
Rationale: Viruses contain either DNA or RNA, not both.
Answer: C. Either DNA or RNA
9. The main purpose of sterilization is to:
A. Reduce microbial load
B. Kill all microorganisms including spores
C. Remove dirt
D. Inhibit growth temporarily
Rationale: Sterilization eliminates all forms of microbial life.
Answer: B. Kill all microorganisms including spores
10. Antibiotics are most effective against:
A. Viruses
B. Fungi only
