Category: MICROBIOLOGY Objective Questions

Microbiology Multiple Choice Questions on “Morphology and Fine Bacteria – Structures External to the Cell Wall”.

1. Bacteria having clusters of flagella at both poles of cells are known as?
A. Lophotrichous
B. Peritrichous
C. Amphitrichous
D. Monotrichous
Answer: C
Clarification: In amphitrichous, flagella occur either singly or in clusters at both cell poles. Lophotrichous refers to a cluster of polar flagella, peritrichous is surrounded by lateral flagella and monotrichous is for a single polar flagella.

2. Salmonella typhi has which type of flagella arrangement?
A. Amphitrichous
B. Peritrichous
C. Monotrichous
D. Lophotrichous
Answer: B
Clarification: Salmonella typhi has peritrichous type of flagella arrangement. In peritrichous, the bacteria are surrounded by lateral flagella.

3. The L Ring in Gram-Negative bacterium flagella is associated with _________
A. Peptidogycan
B. Outer Membrane
C. Cytoplasmic Membrane
D. Cell Membrane
Answer: B
Clarification: The flagella in Gram-Negative bacteria has four basal rings. The L Ring of flagella is associated with the outer membrane. The P ring is associated with the peptidoglycan layer and both the M and S rings are associated with the cytoplasmic membrane.

4. Which among the following acts as a transport protein for protons in flagellar motion?
A. fli protein
B. cGMP
C. atp
D. mot protein
Answer: D
Clarification: The proton binds to the Mot protein and this changes the conformation of Mot protein. It results in releasing the ring and helps in flagellar motion. The fli protein helps in changing the direction of flagella.

5. F pilus has a major role as ___________
A. motility of the cell
B. port of entry of genetic material during mating
C. attachment to host cell
D. human infection
Answer: B
Clarification: Pili are hollow, filamentous appendages that are thinner and shorter. They do not function in motility and have other different functions. One type known as F plus or sex plus serves as the port of entry of genetic material during bacterial mating.

6. Prosthecae helps in __________
A. motility
B. nutrient absorption and attachment to surfaces
C. human infection
D. protection from the environment
Answer: B
Clarification: Prosthecae increases the surface area of the cells for nutrient absorption, which is advantageous in dilute environments. Some prosthecate bacteria have an adhesive substance at the end of a prostheca that aids in attachment to surfaces.

7. The capsule of Klebsiella pneumoniae is composed of heteropolysaccharides.
A. True
B. False
Answer: A
Clarification: Heteroploysaccharides are usually synthesized from sugar precursors that are activated within the cell, attached to a lipid carrier molecule, transported across the cytoplasmic membrane and polymerized outside the cell. The capsule of Klebsiella pneumoniae is an example of heteropolysaccharides.

8. When a bacteria swim towards a chemical, it is termed as__________
A. positive chemotaxis
B. phototaxis
C. negative chemotaxis
D. magnetotaxis
Answer: A
Clarification: When a bacteria swim towards or away from chemical compounds, the phenomenon is known as bacterial chemotaxis. Swimming towards a chemical is termed as positive chemotaxis; swimming away is negative chemotaxis.

9. Which type of force drives the flagellar motion?
A. Protonmotive force
B. ATP driven
C. Protonmotive and ATP driven
D. No protonmotive nor ATP driven
Answer: A
Clarification: It is found that the flagellar motor is driven by the protonmotive force, i.e., the force derived from the electrical potential and the hydrogen-ion gradient across the cytoplasmic membrane.

.

Microbiology Questions and Answers for Experienced people focuses on “Utilization of Energy in Nonbiosynthetic Processes”.

1. Which of the following has no detectable ATPase activity?
A. cilia
B. eukaryotic flagella
C. bacterial flagella
D. endoflagella
Answer: C
Clarification: Bacterial flagella appears to have no machinery for interconverting chemical and mechanical energy. Flagellin, the flagellar protein molecule, has no enzymatic activity i.e. no detectable ATPase activity.

2. Which force drives the flagellar rotation in bacteria?
A. ATP
B. protonmotive force
C. electrons
D. water gradient
Answer: B
Clarification: The flagellar motor is driven by the protonmotive force, i.e., the force derived from the electric potential and the hydrogen gradient across the cytoplasmic membrane and not ATP.

3. Rotary motor of flagella is associated with _________
A. M ring
B. P ring
C. L ring
D. M and S ring
Answer: D
Clarification: The rotary motor is believed to be the two elements in the basal body, the M ring and the S ring. The rod (which is connected to the filament by the hook) is fixed rigidly to the M ring, which rotates freely in the cytoplasmic membrane. The S ring is mounted rigidly on the cell wall.

4. Passive diffusion requires the use of membrane transport proteins for the transport of solute molecules across the membrane.
A. True
B. False
Answer: B
Clarification: In passive diffusion no substance in the membrane interacts specifically with the solute molecules. The difference in concentration gradient governs the rate of the inward flow of solute molecules.

5. The entry of glycerol into the bacterial cells is by ____________
A. passive diffusion
B. facilitated diffusion
C. group translocation
D. active diffusion
Answer: B
Clarification: The entry of glycerol into the bacterial cells is an example of facilitated diffusion which involves the use of a specific protein carrier molecule called a porter for the diffusion of solutes.

6. Porter or permease is located in the _______________
A. cytoplasmic membrane
B. cell membrane
C. nuclear membrane
D. outer membrane
Answer: A
Clarification: Porter or permease is a specific protein carrier molecule that is required in facilitated diffusion which combines reversibly with the solute molecules and releases it into the inside of cell.

7. Facilitated diffusion does not require metabolic energy.
A. True
B. False
Answer: A
Clarification: Both the passive diffusion and facilitated diffusion does not require metabolic energy.

8. The reaction for the transfer of phosphoryl group of phosphoenol pyruvate to the sugar molecule requires which ion?
A. Mg²⁺
B. Fe²⁺
C. O
D. PO₄^2-
Answer: A
Clarification: The reaction for the transfer of phosphoryl group of phosphoenol pyruvate to the sugar molecule requires Mg²⁺, the products formed are sugar phosphate and pyruvate.

9. HPr stands for ______________
A. heat-stable carrier protein
B. hydrogen carrier protein
C. pyruvate dehydrogenase
D. high-energy protein
Answer: A
Clarification: Heat-stable protein (HPr) is activated first by transfer of phosphate group from the high-energy compound phosphoenol pyruvate inside the cell.

10. In phosphotransferase system(PTS), the sugar-phosphate is released inside the cell by which of the following?
A. Enzyme I
B. Enzyme II
C. Enzyme III
D. HPr
Answer: B
Clarification: Enzyme II is specific for a particular sugar, and is an integral component of the cytoplasmic membrane. Here it combines with the phosphate group carried by the activated HPr.The sugar-phosphate is released by enzyme II and enters the cell.

11. Mannitol enzyme II has been purified from _____________
A. E.coli
B. Salmonella typhimurium
C. Saccharomyces cerevisiae
D. Lactobacillus
Answer: A
Clarification: Mannitol enzyme II has been purified from E.coli. Other enzymes can be purified from several other bacteria.

To practice all areas of Microbiology for Experienced people, .

Microbiology Multiple Choice Questions on “Physiology and Cultivation of Fungi”.

1. Pathogenic fungi have a temperature optimum at __________
A. 30 to 37 degree celsius
B. 22 to 30 degree celsius
C. 37 to 42 degree celsius
D. 42 to 50 degree celsius
Answer: A
Clarification: Fungi grow over a wide range of temperatures. Pathogenic species have a higher temperature optimum, generally 30 to 37 degree Celsius.

2. Sabouraud media for the growth of fungi is composed of ____________________
A. glucose and ammonia
B. maltose and peptone
C. sucrose and peptone
D. peptone
Answer: B
Clarification: One of the best known and oldest media for the growth of fungi is Sabouraud media that contains maltose and peptone as its principal ingredients.

3. Sabouraud media has ________________
A. high ph, low sugar concentration
B. high ph, moderate sugar concentration
C. low ph, high sugar concentration
D. low ph, moderate sugar concentration
Answer: C
Clarification: Sabouraud media is widely used for the isolation of molds and certain yeasts. Its partial selective action is due to the high sugar concentration and low pH.

4. Jams and jellies are spoiled by both bacteria and fungi.
A. True
B. False
Answer: B
Clarification: Yeasts and molds can grow in a substrate or medium containing concentrations of sugars that inhibit most bacteria; this is why jams and jellies may be spoiled by molds but not by bacteria.

5. What are the cell wall structural components of fungi?
A. peptidoglycan
B. cellulose
C. chitin
D. chitin,cellulose, or hemicellulose
Answer: D
Clarification: The cell wall structural components of fungi are chitin, cellulose, or hemicellulose whereas the bacterial cell wall is composed of peptidoglycan.

6. The optimum pH for the growth of fungi is ____________
A. 7.8-9.0
B. 12-14
C. 3.8-5.6
D. 1.0-2.0
Answer: C
Clarification: The optimum pH for the growth of fungi is 3.8-5.6. Acidic media (pH 5.6) are tolerated by molds but are inhibitory to most bacteria.

7. Which of the following are the oxygen requirements of molds?
A. Strictly aerobic
B. Facultatively aerobic
C. Anaerobic
D. Microaerophilic
Answer: A
Clarification: Moulds are strictly aerobic whereas yeasts are facultative organisms.

8. Fungi are sensitive to which of the following antibiotics?
A. penicillins
B. tetracyclins
C. chloramphenicol
D. griseofulvin
Answer: D
Clarification: Fungi are resistant to penicillins, tetracyclins, chloramphenicol but are sensitive to griseofulvin.

9. Ordinary inoculating loop can be used for inoculation of yeasts.
A. True
B. False
Answer: A
Clarification: Ordinary inoculating loop used for bacteria is suitable for the inoculation of yeasts. But the needle used for molds is stiffer and has a flattened tip for cutting the mycelium.

.

Microbiology MCQs focuses on “Virus Infection and Fatal Diseases Associated with Viruses in Animals”.

1. Which of the following inclusion bodies are present in the cytoplasm of the Purkinje cells of the cerebellum in the case of rabies infection?
A. Paschen bodies
B. Guarnieri bodies
C. Negri bodies
D. Elementary bodies
Answer: C
Clarification: Characteristic inclusion bodies are found in the cytoplasm of the Purkinje cells of the cerebellum and in certain other nerve cells in cases of rabies infection. These typical inclusion bodies are Negri bodies and is diagnostic of the disease.

2. Bollinger bodies are found in the cytoplasm of cells infected by which of the following viruses?
A. variola virus
B. fowl pox virus
C. rabies virus
D. herpes virus
Answer: B
Clarification: Bollinger bodies are found in the cytoplasm of cells infected with fowl pox virus. It is a type of inclusion body produced by viruses in certain host tissues.

3. Intracytoplasmic inclusions are found in chicken pox, herpes, and the polyhedra diseases of insects.
A. True
B. False
Answer: B
Clarification: Intranuclear inclusions are found in chicken pox, herpes, and the polyhedra diseases of insects. Intranuclear and intracytoplasmic inclusions may be found in the same cell in instances of multiple infections.

4. Scrapie is a chronic disease of which of the following animals?
A. sheep
B. mouse
C. mink
D. cow
Answer: A
Clarification: Scrapie is so named because the diseased animal tends to scrape against fixed objects. It is a chronic infection of the central nervous system of sheep.

5. In which of the following categories of cancer solid tumors grow from derivatives of embryonal mesoderm?
A. Leukemias
B. Lymphomas
C. Sarcomas
D. Carcinomas
Answer: C
Clarification: In Sarcoma solid tumors grow from derivatives of embryonal mesoderm, such as connective tissues, cartilage, bone, muscle and fat.

6. Anaplasia is structural abnormality of cells.
A. True
B. False
Answer: A
Clarification: Cancer has three major characteristics: hyperplasia, anaplasia, and metastasis. Anaplasia is structural abnormality of cells (these cells also have a loss of or reduction in their functions).

7. Which among the following is the family of RNA containing viruses that can cause cancer in animals?
A. Herpesviridae
B. Adenoviridae
C. Papovaviridae
D. Retroviridae
Answer: D
Clarification: Among the viruses whose virions contain RNA, only some members of the family Retroviridae cause cancer in animals. These members replicate through a DNA intermediate.

8. Cancer of the lip of mouth have been associated with ___________
A. HSV1
B. HSV2
C. EBV
D. SV 40
Answer: A
Clarification: HSV1 is a herpes virus type 1 which is associated with the cancer of the lip of the mouth in humans wheras HSV2 causes cervical cancer.

9. The Epstein-Barr virus (EBV) can induce tumors in _____________
A. mouse
B. monkey
C. humans
D. rodents
Answer: C
Clarification: The Epstein-Barr virus (EBV), a herpesvirus, has been consistently associated with certain human neoplasias, or tumors.

To practice MCQs on all areas of Microbiology, .

Microbiology online test focuses on “Determining Sanitary Quality of Water”.

1. Which of the following forms of water is the most contaminated?
A. Underground water
B. Rainwater
C. Surface water
D. Water stored in ice caps
Answer: C
Clarification: Surface water should not be used for drinking purposes unless it is subjected to purification since there is constant danger of contamination and consequent transmission of disease.

2. Alum is used for which of the following purification process?
A. Sedimentation
B. Filtration
C. Disinfection
D. Ozonation
Answer: A
Clarification: Sedimentation is enhanced by addition of alum (aluminum sulphate) at the treatment plant, which produces a sticky flocculent precipitate.

3. The potability of water can be checked by sanitary surveys.
A. True
B. False
Answer: B
Clarification: Sanitary surveys reveal whether water is being produced under conditions in which potable water would ordinarily be produced. However, potability can be determined only by chemical and bacteriological laboratory tests.

4. The coliform group of bacteria includes all the __________________ bacilli.
A. aerobic
B. anaerobic
C. aerobic, non-sporulating
D. aerobic, gram-negative, non-sporulating
Answer: D
Clarification: The coliform group of bacteria includes all the aerobic and facultatively anaerobic, gram-negative, non-sporulating bacilli that produce acid and gas from the fermentation of lactose.

5. Which of the following organism does not belong to coliform group of bacteria?
A. Salmonella
B. Serratia
C. Enterobacter
D. Proteus
Answer: C
Clarification: Coliform group of bacteria consists of E.coli and Enterobacter aerogenes. All others belong to the enteric group.

6. Coliforms are natural inhabitants of the large intestine of human and animals.
A. True
B. False
Answer: A
Clarification: Coliforms, fecal streptococci and Clostridium perfringens are normal inhabitants of the large intestine of humans and other animals and are consequently present in feces.

7. Which of the following acts as a carbon source for Enterobacter aerogenes?
A. Peptone
B. Sodium citrate
C. Yeast extract
D. Tryptone
Answer: B
Clarification: Enterobacter aerogenes will grow in a chemically defined medium in which sodium citrate is the only carbon compound as it is capable of utilizing it.

8. What will be the plate count of good quality water?
A. 10 per ml
B. 50 per ml
C. 100 per ml
D. 1000 per ml
Answer: C
Clarification: In the standard plate count method, water of good quality is expected to give a low count, less than 100 per ml.

9. Among the following which microorganism acts as a representative of fecal streptococci group?
A. Streptococcus faecalis
B. Streptococcus bovis
C. Streptococcus equinus
D. Streptococcus faecium
Answer: A
Clarification: Streptococcus faecalis is representative of the fecal streptococci group and are abundantly present in the large intestine of humans. Their occurrence in water is indicative of fecal pollution.

10. Thiobacillus can produce an acidity in the range of pH __________
A. 7
B. 5
C. 3
D. 1
Answer: D
Clarification: Organisms of the genus Thiobacillus oxidize elemental sulphur to sulphuric acid and can produce acidity in the range of pH 1.

11. In which of the following organism does iron secreted to form stalks or ribbons attached to the cell?
A. Sphaerotilus
B. Gallionella
C. Thiobacillus
D. Streptococcus
Answer: B
Clarification: Some iron bacteria such as Gallionella transform soluble compounds of iron to insoluble compounds of iron which are secreted to form stalks or ribbons attached to the cell.

To practice all areas of Microbiology for online tests, .

Microbiology Multiple Choice Questions on “Infection Process – Microbial Adherence”.

1. Degree of pathogenicity is referred to as _________________
A. infection
B. virulence
C. avirulent
D. attenuated
Answer: B
Clarification: Various strains of pathogenic species differ with regard to their degree of pathogenicity, i.e., with regard to their virulence.

2. Which type of strains are used in vaccines?
A. virulent
B. avirulent
C. attenuated
D. non-pathogenic
Answer: C
Clarification: Attenuated strains are widely used as vaccines to elicit immunity to various diseases.

3. The LD50 dose can be determined more precisely than LD100 dose.
A. True
B. False
Answer: A
Clarification: The LD50 dose can be determined more precisely than LD100 dose because the rate of change in mortality versus change in dose is greatest around the point of 50 percent mortality.

4. Which of the following characteristics of the microorganism does not help in causing infectious disease?
A. must enter the host
B. must metabolize in the host tissue
C. must resist host defenses
D. must not damage the host
Answer: D
Clarification: The pathogenic microorganism after entering the host must also damage the host to cause any infectious disease.

5. Microbial adherence is selective in nature.
A. True
B. False
Answer: A
Clarification: Microbial adherence or attachment of the pathogen to some surface of the host is selective: various pathogens attach only to certain tissues.

6. When the infection occurs suddenly and with severe intensity it is known as ______________
A. chronic
B. fulminating
C. acute
D. localized
Answer: B
Clarification: Fulminating type of infection occurs suddenly and with severe intensity. An example is cerebrospinal meningitis caused by Neisseria meningitidis.

7. Tuberculosis is which type of infection?
A. acute
B. chronic
C. primary
D. secondary
Answer: B
Clarification: Chronic infections are those diseases which has a long duration like tuberculosis disease.

8. Where does Streptococcus pyogenes infects in the body to cause infection?
A. cervix
B. small intestine
C. urethra
D. throat
Answer: D
Clarification: Streptococcus pyogenes, the causative agent of streptococcal sore throat, attaches specifically to the epithelial cells of the throat by means of cell wall proteins.

9. Vibrio cholerae adheres to the epithelial cells of the small intestine by means of ______________
A. pili
B. proteins
C. hemagglutinin
D. hydrogen bonds
Answer: C
Clarification: Vibrio cholerae adheres to the epithelial cells of the small intestine of humans by means of hemagglutinin.

10. Poliovirus attaches to central nervous system by means of ______________
A. pili
B. proteins
C. hemagglutinin
D. hydrogen bonds
Answer: B
Clarification: There is a protein on the surface of poliovirus which seems to be critical for attachment of the virus to lipid- and glycoprotein- containing receptors on the host cells; the attachment is specific for cells of the intestinal tract and central nervous system.

.