Here are 1000 MCQs on Microbiology (Chapterwise).
1. What is Microbiology?
a) Study of molecules that are visible to human eyes
b) Study of animals and their family
c) Study of organisms that are not visible to naked eyes
d) Study of microscope
View Answer
Explanation: Study of organisms that are not visible to naked eyes is known as Microbiology. A special device known as a microscope is required to view these organisms. Example: Bacteria, viruses, fungi, etc.
2. Who is known as the father of Microbiology?
a) Edwin John Butler
b) Ferdinand Cohn
c) Robert Koch
d) Antoni van Leeuwenhoek
View Answer
Explanation: Antoni van Leeuwenhoek, a Delft cloth merchant, is considered the father of microbiology. He discovered the invisible world of microorganisms using homemade microscopes.
3. Which microorganism(s) among the following perform photosynthesis by utilizing light?
a) Cyanobacteria, Fungi and Viruses
b) Viruses
c) Cyanobacteria
d) Fungi
View Answer
Explanation: Cyanobacteria require light as a source of energy to perform photosynthesis. Fungi and viruses are unable to perform photosynthesis and are heterotrophic.
4. Which part of the compound microscope helps in gathering and focusing light rays on the specimen to be viewed?
a) Condenser lens
b) Magnifying lens
c) Objective lens
d) Eyepiece lens
View Answer
Explanation: Compound microscope contains three separate lens systems. The condenser lens is placed between the light source and the specimen and it gathers and focuses the light rays in the plane of the microscopic field to view the specimen.
5. Which of the following are produced by microorganisms?
a) Alcoholic beverages
b) Fermented dairy products
c) Breads
d) All of the mentioned
View Answer
Explanation: Microorganisms are used in many industries for the production of food we eat, like fermented dairy products (sour cream, yogurt), as well as fermented foods as pickles, breads and alcoholic beverages.
6. What is the approximate size of the bacterial cell?
a) 1mm in diameter
b) 0.5 to 1.0 micrometer in diameter
c) 2mm in diameter
d) 2 micrometer in diameter
View Answer
Explanation: Bacteria are very small, most being approximately 0.5 to 1.0 micrometer in diameter. This is the reason why they cannot be seen by naked eyes and can be observed under the microscope.
7. The greatest resolution in light microscopy can be obtained with ___________
a) Shortest wavelength of visible light used
b) Longest wavelength of visible light used
c) An objective with minimum numerical aperture
d) Shortest wavelength of visible light used and an objective with the maximum numerical aperture
View Answer
Explanation: The relationship between numerical aperture (NA) and resolution is:-
Resolution (d) = wavelength / 2(NA)
Thus maximum resolution is obtained with the shortest wavelength of visible light and an objective with the maximum NA.
8. Which of the following is used in electron microscope?
a) electron beams and magnetic fields
b) light waves
c) magnetic fields
d) electron beams
View Answer
Explanation: Electron Microscope uses electron beams and magnetic fields to produce the image, whereas the light microscope uses light waves and glass lenses. In electron microscopy, a much higher resolution is obtained with extremely short wavelength of the electron beam.
9. Which among the following are “Spirochetes”?
a) Streptomyces sp.
b) Treponema pallidum
c) Spirillum volutans
d) Corynebacterium diphtheriae
View Answer
Explanation: Spirochetes are flexible and can twist and contort their shape, whereas spirilla are relatively rigid. Treponema palldium belongs to the spirochetes group and Spirillum volutans belong to the spirilla group.
10. Bacteria having clusters of flagella at both poles of cells are known as?
a) Amphitrichous
b) Monotrichous
c) Peritrichous
d) Lophotrichous
View Answer
Explanation: 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.
11. The respiratory chain of bacteria is associated with the _____________
a) cytoplasmic membrane
b) cell wall
c) cytoplasm
d) mitochondrial membrane
View Answer
Explanation: The respiratory chain of bacteria is associated with the cytoplasmic membrane and that of eukaryotes is present in the mitochondrial membrane.
12. Glycolysis can occur in ___________
a) anaerobic cells
b) aerobic cells
c) neither aerobic and anaerobic cells
d) both aerobic and anaerobic cells
View Answer
Explanation: Glycolysis does not require the presence of oxygen and therefore can occur in both aerobic and anaerobic cells. In anaerobic cells glucose is degraded into fermentation products and in aerobic cells glucose is degraded into carbon dioxide and water.
13. Which of the following enzyme removes the RNA primer with its 5’-nuclease activity?
a) DNA polymerase III
b) RNA polymerase
c) DNA polymerase I
d) DNA polymerase II
View Answer
Explanation: DNA polymerase I remove the RNA primer with its 5”-nuclease activity; simultaneously it fills in the gap with DNA via its 3’-polymerase activity.
14. Phosphorus is essential component of __________
a) phospholipids
b) teichoic acid
c) nucleotides
d) All of the mentioned
View Answer
Explanation: Phosphorus, usually supplied in the form of phosphate, is an essential component of nucleotides, nucleic acids, phospholipids, teichoic acids, and other components.
15. The bacterium Staphylococcus aureus is which type of bacteria?
a) Mesophile
b) Mesophile and psychrophile
c) Psychrophile
d) Thermophile
View Answer
Explanation: Staphylococcus aureus is a mesophilic bacteria which can grow in the temperature range of 6.5-46 degree Celsius and has an optimum temperature at 30-37 degree Celsius.
16. Growth of bacteria or microorganisms refer to __________________
a) changes in the total population
b) an increase in number of cells
c) an increase in the size of an individual organism
d) an increase in the mass of an individual organism
View Answer
Explanation: Growth denotes the increase in number of cells beyond that present in the original inoculum. It does not refer to an increase in size or mass of an individual organism.
17. Which of the following method can be used to determine the number of bacteria quantitatively?
a) Spread-plate
b) Streak-plate
c) Pour-plate and spread plate
d) Pour plate
View Answer
Explanation: Due to a higher degree of dilution, pour-plate and spread-plate techniques may be performed in a quantitative manner to determine the number of bacteria present in a specimen.
18. Which among the following are microaerophilic bacteria?
a) Treponema
b) Borrelia
c) Spirochaeta
d) Cristispira
View Answer
Explanation: Borrelia is the genus of bacteria belonging to the class Spirochaetaceae and are microaerophilic.
19. Penicillin causes inhibition of Mycoplasmas.
a) False
b) True
View Answer
Explanation: Because of the lack of a cell wall, mycoplasmas are not inhibited by even high levels of penicillin; however, they can be inhibited by antibiotics that affect protein synthesis, such as tetracyclines or chloramphenicol.
20. What are the cell wall structural components of fungi?
a) peptidoglycan
b) cellulose
c) chitin
d) chitin, cellulose, or hemicellulose
View Answer
Explanation: The cell wall structural components of fungi are chitin, cellulose, or hemicellulose whereas the bacterial cell wall is composed of peptidoglycan.
21. Cryptococcosis is a disease of ________________
a) viral infection
b) mycotic infection
c) parasitic infection
d) bacterial infection
View Answer
Explanation: Cryptococcus neoformans is an important basidiomycetous pathogen of humans, causing cryptococcosis, a generalized mycotic infection involving the bloodstream as well as lungs, central nervous system and other organs.
22. Which among the following is a pathogenic algae for humans?
a) Cephaleuros
b) Acanthopeltis
c) Chlorella
d) Prototheca
View Answer
Explanation: Prototheca has been found to be a probable pathogen of humans. It has been found in systemic and subcutaneous infections, as well as in bursitis.
23. Chrysolaminarin is the reserved food of ___________________
a) Bacillariophycophyta
b) Xanthophycophyta
c) Chlorophycophyta
d) Phaeophycophyta
View Answer
Explanation: Chrysolaminarin is the reserved food of Xanthophycophyta which is the yellow-green algae along with oils.
24. Protozoa that eat other organisms are known as _______________
a) parasitic
b) mutualistic
c) holozoic
d) saprophytic
View Answer
Explanation: Holozoic protozoa are protozoa that eat other organisms. Species of Paramecium are holozoic and they must have a supply of bacteria or other protozoa.
25. Plasmodium divides by which of the following method most commonly?
a) Regeneration
b) Budding
c) Binary fission
d) Multiple fission
View Answer
Explanation: The malarial parasite, Plasmodium divides by the process of multiple fission where it is known as schizogony and serves to spread the parasite quickly in the host.
26. Which of the following is a family of lambda phage viruses?
a) Styloviridae
b) Corticoviridae
c) Microviridae
d) Pedoviridae
View Answer
Explanation:Styloviridae is a family of lambda phage viruses that are non-enveloped and has dsDNA.
27. What does a viral DNA becomes after being associated with the bacterial chromosome?
a) plasmid
b) plaque
c) prophage
d) gene
View Answer
Explanation: In lysogeny the viral DNA of the temperate phage, instead of taking over the functions of the cell’s genes, is incorporated into the host DNA and becomes a prophage in the bacterial chromosome, acting as a gene.
28. Vaccination was invented by ____________
a) Watson
b) Jenner
c) Crick
d) Pasteur
View Answer
Explanation: In 1796 Jenner first vaccinated an 8-year old boy with material removed from cow and it gave protection against the smallpox virus.
29. For which viral disease, vaccine has been recently developed through the use of tissue culture?
a) S mallpox
b) Rabies
c) Mumps
d) Measles
View Answer
Explanation: Among the virus diseases for which vaccines have been recently developed through the use of tissue culture is measles (rubeola).
30. Which of the following inhibits DNA replication?
a) x-rays
b) gamma rays
c) UV light
d) cathode rays
View Answer
Explanation: Ultraviolet light is absorbed by many cellular materials but most significantly by the nucleic acids where it does the most damage. Pyrimidine dimers are formed due to which DNA replication is inhibited and mutations can result.
31. Which was the first disease for which a chemotherapeutic agent was used?
a) Small pox
b) Syphilis
c) AIDS
d) Malaria
View Answer
Explanation: Syphilis is the first known disease for which a chemotherapeutic agent was used. An arsenical compound known as Salvarsan was synthesized by Paul Ehrlich in 1910 to treat this disease.
32. Bacterial cells grown in a medium exposed to high osmotic pressure, changes shape from rod-shaped to __________ shaped.
a) elongated
b) irregular
c) rod shaped
d) spherical
View Answer
Explanation: The high osmotic pressure prevents the cells from bursting. Rod-shaped cells become spherical because they lack the cell structure which imparts shape.
33. Tyrocidines are more effective against ___________________
a) Gram-negative organisms
b) Gram-positive organisms
c) Spirochetes
d) Mycoplasmas
View Answer
Explanation: Tyrocidines and gramicidines are more effective against Gram-positive organisms whereas polymyxins are particularly effective against Gram-negative bacteria.
34. Which of the following is the most accurate method for microbial assay of antibiotics?
a) Chemical and biological assay
b) Biological assay
c) Chemical assay
d) Physical assay
View Answer
Explanation: Chemical-assay methods are generally more accurate and require less time than biological methods, but they are less sensitive, and caution must be used lest biologically inactive degradation products give misleading results.
35. Which among the following is not an ammonia-oxidizing bacteria?
a) Nitrospina gracilis
b) Nitrosococcus oceanus
c) Nitrosomonas europaea
d) Nitrosovibrio tenuis
View Answer
Explanation: Nitrospina gracilis is a nitrite-oxidizing bacteria. They are involved in the oxidation of nitrite to nitrate.
36. Cellulose is degraded to cellobiose by the enzyme __________________
a) cellulose dehydrogenase
b) hexokinase
c) beta-glucosidase
d) cellulase
View Answer
Explanation: The most abundant organic material in plants is cellulose. The initial enzymatic at-tack is by cellulase which splits this long-chain polymer of glucose to cellobiose which contains two glucose units.
37. Sulphates are reduced to hydrogen sulphide by _____________________
a) Thiobacillus thiooxidans
b) Rhodospirillum
c) Desulfotomaculum sp.
d) Photosynthetic sulfur bacteria
View Answer
Explanation: Sulphates are reduced to hydrogen sulphide by soil microorganisms like Desulfotomaculum species. Like calcium sulphate gives us hydrogen sulphide and calcium hydroxide.
38. The microorganisms from lakes and rivers can grow at a salt concentration of _________
a) above 1 percent
b) below 1 percent
c) 2.5 to 4 percent
d) 5 percent
View Answer
Explanation: Microorganisms from lakes and rivers are salt sensitive and do not grow at a salt concentration of more than 1 percent whereas marine microorganisms are halophilic.
39. In regions of the estuary that are nutritionally poor, it is more likely to find which of the following organisms?
a) viruses
b) coliforms
c) fecal streptococci
d) appendaged bacteria
View Answer
Explanation: In regions of the estuary that are nutritionally poor, one is likely to find the budding and/or the appendaged bacteria, in addition to pseudomonads.
40. In which of the following treatment involve oxidation of organic constituents of the wastewater?
a) Final treatment
b) Advanced treatment
c) Secondary treatment
d) Primary treatment
View Answer
Explanation: Secondary or biological treatment is done to adsorb and ultimately oxidize organic constituents of the wastewater, i.e, to reduce the BOD.
41. Which among the following group of microorganisms are found in the ducts of cow’s mammary glands?
a) Micrococci
b) Microbacteria
c) Lactobacilli
d) Coliforms
View Answer
Explanation: Micrococci such as Micrococcus luteus, Micrococcus varians are found in the ducts of cow’s mammary glands and dairy utensils. They are acid producers and are weakly proteolytic.
42. Which of the following microorganism is eliminated in canned foods?
a) Lactobacillus
b) Clostridium botulinum
c) Mycobacterium tuberculosis
d) Coxiella burnetii
View Answer
Explanation: The most important organism to be eliminated in canned foods is the spore forming anaerobe Clostridium botulinum, which is capable of producing a very potent lethal toxin.
43. Bacterial cell grown on hydrocarbon wastes from the petroleum industry are a source of _____________
a) fats
b) vitamins
c) carbohydrates
d) proteins
View Answer
Explanation: The microorganisms can be cultivated on industrial wastes or by-products as nutrients and yield a large cell crop that is rich in protein. Bacterial cell grown on hydrocarbon wastes from the petroleum industry are a source of protein in France, Japan, Taiwan, and India.
44. Which of the following microorganism produces dextran?
a) Leuconostoc mesenteroides
b) Streptomyces olivaceus
c) Bacillus thuringiensis
d) Bacillus polymyxa
View Answer
Explanation: Leuconostoc mesenteroides is the producer organism for dextran which acts as a stabilizer in food products and as a blood plasma substitute.
45. The principal microorganism for yogurt is ______________________
a) Leuconostoc citrovorum
b) Streptococcus lactis
c) Streptococcus thermophilus
d) Lactobacillus acidophilus
View Answer
Explanation: Streptococcus thermophilus and Lactobacillus bulgaricus are among the principal microorganisms responsible for producing yogurt by fermentation.
46. Which of the following yeast can be used to produce microbial protein?
a) Eremothecium ashbyi
b) Candida utilis
c) Saccharomyces cerevisiae
d) Candida milleri
View Answer
Explanation: Candida utilis is yeast used for producing microbial protein which is used as an animal food supplement (single-cell protein) from paper-pulp waste.
47. Acridine orange is which type of mutagen?
a) chemical compounds
b) transposons
c) base analog
d) intercalating agents
View Answer
Explanation: Acridine orange is an intercalating agent that can intercalate between the base pairs in the central stack of the DNA helix and distort the structures and cause subsequent replication errors.
48. Lipopolysaccharide in cell walls is characteristic of?
a) Algae
b) Fungi
c) Gram-negative bacteria
d) Gram-positive bacteria
View Answer
Explanation: The occurrence of lipopolysaccharide in cell walls is characteristic of Gram-negative bacteria; whereas Gram-positive bacteria have cell walls that contain teichoic acid. Fungal and algal cell walls are very different in composition from those of bacteria.
49. Which of the following are present in teichoic acids?
a) glycerol residues
b) ribitol residues
c) ribitol or glycerol residues
d) glucose residues
View Answer
Explanation: The teichoic acids are water-soluble polymers, containing ribitol or glycerol residues joined through phosphodiester linkages. The glycerol or ribitol is joined to a sugar residue such as glucose, galactose or N-acetyl glucosamine.
50. Which of the following are true for cytoplasmic membrane?
a) site of generation of protonmotive force
b) hydrophilic barrier
c) hydrophobic barrier
d) hydrophobic barrier and site of generation of protonmotive force
View Answer
Explanation: The cytoplasmic membrane is a hydrophobic barrier to penetration by most water-soluble molecules. Because of its impermeability to protons, the cytoplasmic membrane is the site of the generation of the proton motive force.
Chapterwise Multiple Choice Questions on Microbiology
- The Characterization, Classification and Identification of Microorganisms
- The Microscopic Examination of Microorganisms
- The Morphology and Fine Structure of Bacteria
- The Cultivation of Bacteria
- Reproduction and Growth
- Pure Cultures and Cultural Characteristics
- Microbial Metabolism : Energy Production
- Microbial Metabolism : Utilization of Energy and Biosynthesis
- The World of Bacteria I & II
- Fungi – Molds and Yeasts
- Algae & Protozoa
- Viruses of Bacteria
- Viruses of Animals and Plants
- The Control of Microorganisms by Physical & Chemical Agents
- Antibiotics and Other Chemotherapeutic Agents
- Microbiology of Soil & Aquatic Microbiology
- Microbiology of Domestic Water and Wastewater, Microbiology of Food
- Industrial Microbiology & Bacterial Genetics
- Microbial Flora of the Healthy Human Host, Host-Microbe Interactions : The Process of Infection
- Microbial Agents of Disease : Bacteria & Viruses
- Microbial Agents of Disease : Fungi and Protozoa
Microbiology MCQ Section 1 – Classification and Identification of Microorganisms
The section contains multiple choice questions and answers on microorganisms characteristics and microbial classification.
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Microbiology MCQ Section 2 – Microscopic Examination of Microorganisms
The section contains questions and answers on light microscope, microbial Stains, transmission and scanning electron microscope.
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Microbiology MCQ Section 3 – Morphology and Fine Structure of Bacteria
The section contains MCQs on size, shape and arrangement of bacterial cells, cell wall, structures external and internal to the cell wall.
Microbiology MCQ Section 4 – Cultivation of Bacteria
The section contains multiple choice questions and answers on nutritional requirements, bacteriological media and physical conditions growth.
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Microbiology MCQ Section 5 – Reproduction and Growth
The section contains questions and answers on cell division modes, bacteria growth cycle and quantitative measurement.
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Microbiology MCQ Section 6 – Pure Cultures and Cultural Characteristics
The section contains MCQs on selective methods, pure cultures and cultural characteristics.
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Microbiology MCQ Section 7 – Energy Production
The section contains multiple choice questions and answers on bioenergetics principles, energy production by photosynthesis, anaerobic and aerobic processes.
Microbiology MCQ Section 8 – Utilization of Energy and Biosynthesis
The section contains questions and answers on energy utilization in biosynthetic and nonbiosynthetic processes, transcription and translation of genetic information and protein synthesis process.
Microbiology MCQ Section 9 – World of Bacteria I & II
The section contains MCQs on spirochetes, negative rods, cocci, facultatively anaerobic gram, rickettsias and chlamydias, mycoplasmas, positive cocci and positive bacteria.
Microbiology MCQ Section 10 – Fungi (Molds and Yeasts)
The section contains multiple choice questions and answers on morphology, reproduction, physiology and fungi cultivation, fungi classification and special interest.
Microbiology MCQ Section 11 – Algae & Protozoa
The section contains questions and answers on biological and economic importance of algae, algae characteristics and classification, ecology and protozoa importance, protozoa characteristics, protozoa morphology and reproduction.
Microbiology MCQ Section 12 – Viruses of Bacteria
The section contains MCQs on phages structure and morphology, bacterial viruses replication, lysogeny and lytic.
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Microbiology MCQ Section 13 – Viruses of Animals and Plants
The section contains multiple choice questions and answers on viruses, vaccination, structure, composition, viruses classification, virus infection and fatal diseases.
Microbiology MCQ Section 14 – Control of Microorganisms by Physical & Chemical Agents
The section contains questions and answers on control fundamentals, physical agents, chemical agents characteristics, antimicrobial agents groups and antimicrobial chemical agents evaluation.
Microbiology MCQ Section 15 – Antibiotics and Other Chemotherapeutic Agents
The section contains MCQs on chemotherapy historical highlights, antibiotics and their actions, microbiological assay of antibiotics, antifungal, antiviral and antitumour antibiotics.
Microbiology MCQ Section 16 – Microbiology of Soil & Aquatic Microbiology
The section contains multiple choice questions and answers on soil microorganisms interactions, nitrogen, carbon and sulphur cycles, aquatic environment, aquatic microorganisms techniques and productivity.
Microbiology MCQ Section 17 – Microbiology of Food, Domestic Water and Wastewater
The section contains questions and answers on sanitary quality of water, wastewater, treatment processes, fresh foods microbial flora, food preservation and microorganisms.
Microbiology MCQ Section 18 – Industrial Microbiology & Bacterial Genetics
The section contains MCQs on microorganisms, industry, industrial uses of bacteria, molds and yeasts, genotypic changes, bacterial recombination and conjugation, bacterial transduction and transformation.
Microbiology MCQ Section 19 – Microbial Flora of the Healthy Human Host & Host-Microbe Interactions
The section contains multiple choice questions and answers on normal flora, human host, normal flora distribution, microbial adherence, epithelial cell layers penetration and microbial virulence factors.
Microbiology MCQ Section 20 – Bacteria & Viruses
The section contains questions and answers on diseases caused by staphylococcus, streptococcus, corynebacterium, aerobic and anaerobic gram, viruses containing single and double stranded dna.
Microbiology MCQ Section 21 – Fungi and Protozoa
The section contains MCQs on diseases caused by fungi and protozoa, therapeutic drugs for fungal treatment and protozoan diseases.
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Wish you the best in your endeavor to learn and master Microbiology!