MICROBIOLOGY EXAM MOCK OA QUESTIONS WITH
VERIFIED ANSWERS LATEST UPDATE 2024
1. Which of the following microorganisms lack mitochondria? a. Fungi
b. Bacteria
c. Parasites
d. Protists
Bacteria do not contain membrane-bound organelles such as mitochondria or chloroplasts, as
eukaryotes do.
2. Which bacteria have cell walls that are approximately 10-20% peptidoglycan? a. Gram-positive
b. Gram-negative
c. Acid-fast
d. Wall deficient
80 – 90% peptidoglycan in gram-positive bacteria 20 – 80%
peptidoglycan in gram-negative bacteria
3. Which bacteria are difficult to Gram stain?
a. Gram positive
,b. Gram negative
c. Acid fast
d. Wall deficient
Gram staining is based on the chemical and physical properties of their cell walls. Primarily, it detects
peptidoglycan, which is present in a thick layer in Gram-positive bacteria.
4. Which of the following types of bacteria are slow growing, due to the high lipid content of
their cell walls?
1. Gram-positive
2. Gram-negative
3. Acid-fast
4. Wall deficient
The mycolic acids and other glycolipids also impede the entry of chemicals causing the organisms to
grow slowly and be more resistant to chemical agents and lysosomal components of phagocytes than
most bacteria
5. Which of the following types of bacteria have cell walls that contain sterols?
1. Gram-positive
2. Gram-negative
,3. Acid-fast
4. Wall deficient
The presence of sterols in the membrane contributes to their durability by helping to increase the
forces that hold the membrane together. Other bacterial species occasionally mutate or respond to
extreme nutritional conditions by forming cells lacking walls, termed L-forms. The presence of sterols
in membrane helps in regulation of membrane fluidity.
6. Which of the following types of bacteria have both a cell membrane and an outer
membrane? 1. Gram-positive
2. Gram-negative
3. Acid-fast
4. Wall deficient
In Gram-negative bacteria the outer membrane is usually thought of as part of the outer leaflet of the
membrane structure and is relatively permeable. It contains structures that help bacteria adhere to
animal cells and cause disease
, 7. Which of the following is an endotoxin, which can cause fever and inflammation,
and is associated with Gram-negative bacteria? a. Teichoic acid
b. Periplasmic space
c. Peptidoglycan
d. Lipopolysaccharide
Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria.
Lipopolysaccharide is localized in the outer layer of the membrane and is, in noncapsulated strains,
exposed on the cell surface. LPS is also called an endotoxin because it is a toxin located inside the
bacterial cell. It was originally theorized that endotoxin is released once the bacteria dies. ... LPS is
structurally divided into three main parts, the O-antigen, the Core oligosaccharide and Lipid-A.
8. Which of the following structures is associated with Gram-negative bacteria and is an active
area of cell metabolism? a. Teichoic acid
VERIFIED ANSWERS LATEST UPDATE 2024
1. Which of the following microorganisms lack mitochondria? a. Fungi
b. Bacteria
c. Parasites
d. Protists
Bacteria do not contain membrane-bound organelles such as mitochondria or chloroplasts, as
eukaryotes do.
2. Which bacteria have cell walls that are approximately 10-20% peptidoglycan? a. Gram-positive
b. Gram-negative
c. Acid-fast
d. Wall deficient
80 – 90% peptidoglycan in gram-positive bacteria 20 – 80%
peptidoglycan in gram-negative bacteria
3. Which bacteria are difficult to Gram stain?
a. Gram positive
,b. Gram negative
c. Acid fast
d. Wall deficient
Gram staining is based on the chemical and physical properties of their cell walls. Primarily, it detects
peptidoglycan, which is present in a thick layer in Gram-positive bacteria.
4. Which of the following types of bacteria are slow growing, due to the high lipid content of
their cell walls?
1. Gram-positive
2. Gram-negative
3. Acid-fast
4. Wall deficient
The mycolic acids and other glycolipids also impede the entry of chemicals causing the organisms to
grow slowly and be more resistant to chemical agents and lysosomal components of phagocytes than
most bacteria
5. Which of the following types of bacteria have cell walls that contain sterols?
1. Gram-positive
2. Gram-negative
,3. Acid-fast
4. Wall deficient
The presence of sterols in the membrane contributes to their durability by helping to increase the
forces that hold the membrane together. Other bacterial species occasionally mutate or respond to
extreme nutritional conditions by forming cells lacking walls, termed L-forms. The presence of sterols
in membrane helps in regulation of membrane fluidity.
6. Which of the following types of bacteria have both a cell membrane and an outer
membrane? 1. Gram-positive
2. Gram-negative
3. Acid-fast
4. Wall deficient
In Gram-negative bacteria the outer membrane is usually thought of as part of the outer leaflet of the
membrane structure and is relatively permeable. It contains structures that help bacteria adhere to
animal cells and cause disease
, 7. Which of the following is an endotoxin, which can cause fever and inflammation,
and is associated with Gram-negative bacteria? a. Teichoic acid
b. Periplasmic space
c. Peptidoglycan
d. Lipopolysaccharide
Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria.
Lipopolysaccharide is localized in the outer layer of the membrane and is, in noncapsulated strains,
exposed on the cell surface. LPS is also called an endotoxin because it is a toxin located inside the
bacterial cell. It was originally theorized that endotoxin is released once the bacteria dies. ... LPS is
structurally divided into three main parts, the O-antigen, the Core oligosaccharide and Lipid-A.
8. Which of the following structures is associated with Gram-negative bacteria and is an active
area of cell metabolism? a. Teichoic acid
