Interview MCQ Set 1
1. Which of the following symmetry is exhibited by rod-shaped viruses?
Answer: b [Reason:] The animal and plant viruses are composed of a central core of nucleic acid surrounded by a capsid, which is made up of capsomeres. They exhibit a characteristic symmetry like the rod-shaped viruses have a helical symmetry.
2. The envelope surrounding the nucleocapsid of some animal viruses is made up of which of the following structures?
Answer: a [Reason:] In some animal viruses the nucleocapsid is covered by an outer membranelike structure called the envelope, which is made up of lipoproteins and conceals the symmetry.They are sensitive to lipid solvents such as ether and chlorofoam.
3. Adenoviruses exhibit which of the following symmetry?
a) helical symmetry
b) circular symmetry
c) icosahedral symmetry
d) complex structure symmetry
Answer: c [Reason:] Adenoviruses which cause respiratory infections are examples of icosahedral viruses.
4. The fringes on animal viruses like influenza virus is made up of ______________
Answer: b [Reason:] In the influenza virus the nucleocapsid is a flexible structure packed within a fringed lipoprotein envelope.The fringes are actually spiked projections made of glycoproteins.
5. Animal and plant viruses contain both DNA and RNA in the same virion.
Answer: b [Reason:] Like bacteriophages, animal and plant viruses contain either DNA or RNA, but never both in the same virion.
6. Parvoviruses contain how many genes?
a) 100 genes
b) 500 genes
c) 40 genes
d) 3 genes
Answer: d [Reason:] If 1 kilobase is considered as the size of an average gene, small viruses like parvoviruses and picornaviruses contain perhaps 3 or 4 genes and large viruses contain several hundred.
7. In papovaviruses, DNA occurs in which of the following forms?
a) linear dsDNA
b) linear ssDNA
c) supercoiled circular dsDNA
d) supercoiled circular ssDNA
Answer: c [Reason:] In papovaviruses, DNA occurs as a supercoiled circular dsDNA.Supercoiling refers to the extra turns in the structure of dsDNA due to the action of the enzyme DNA gyrase.
8. In which of the following viruses DNA forms hairpins?
Answer: a [Reason:] In ssDNA parvoviruses the terminal bases of linear DNA exist as inverted repeat sequences that form hairpins.That is, the sequence of terminal bases on each strand of such DNA maybe represented as ABCD…….D’C’B’A’, where ABCD are complementary to A’B’C’D’.
9. RNA in animal viruses exist as circular dsRNA.
Answer: b [Reason:] Some plant viruses appear to have a genome of circular dsRNA.But the RNA in animal viruses exists only as linear double-stranded or single-stranded molecules.
10. Which of the following are characteristics of the process viropexis?
a) phagocytic process
b) plant viruses penetrate host cells through ectodesmata
c) occurs by the enzyme RNA polymerase
d) phagocytic process and occurs by the enzyme lysosomal proteases
Answer: d [Reason:] Engulfment of whole virions by the cells occurs in a phagocytic process called viropexis, followed by uncoating or removal of the capsid.This takes place in th phagocytic vacuoles and is due to the action of the enzymes called lysosomal proteases.
11. Which of the following viruses carry minus-strand RNA?
d) tobacco mosaic viruses
Answer: a [Reason:] RNA viruses like rhabdoviruses,orthomyxoviruses,paramyxoviruses carry minus-strand RNA and they must first transcribe their RNA to form the plus strand that can function as mRNA. This transcription is catalyzed by a viral RNA polymerase.
Interview MCQ Set 2
1. Bacteria having cluster of flagella at both poles of cells are known as?
Answer: c [Reason:] 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?
Answer: b [Reason:] Salmonella typhi has peritrichous type of flagella arrangement. In peritrichous, the bacteria is surrounded by lateral flagella.
3. The L Ring in a Gram-Negative bacterium flagella is associated with_________
b) Outer Membrane
c) Cytoplasmic Membrane
d) Cell Membrane
Answer: b [Reason:] 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
d) mot protein
Answer: d [Reason:] 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 [Reason:] 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 __________
b) nutrient absorption and attachment to surfaces
c) human infection
d) protection from environment
Answer: b [Reason:] 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.
Answer: a [Reason:] 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
c) negative chemotaxis
Answer: a [Reason:] When a bacteria swims 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 [Reason:] It is found that 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.
Interview MCQ Set 3
1. Polyisoprenoid branched-chain lipids, are present in which of the following?
c) Archaebacteria and Eubacteria
d) Cannot be determined
Answer: a [Reason:] In Archaebacteria,the lipids are polyisoprenoid branched-chain lipids, in which long-chain branched alcohols(phytanols) are ether linked to glycerol.In Eubacteria,the phospholipids are phosphoglycerides, in which straight-chain fatty acids are ester-linked to glycerol.
2. Cytoplasmic membrane and the cell material bounded by it plus the outer membrane of cell is known as _________
d) Cell membrane
Answer: c [Reason:] A protoplast is that portion of a bacterial cell consisting of the cytoplasmic membrane and the cell material bounded by it. When the cell has two membranes, the cytoplasmic membrane of the protoplast plus the outer membrane of the cell wall, the cell is called a spheroplast rather than protoplast.
3. Which among the following is associated with export of exocellular enzymes?
a) central mesosomes
b) peripheral mesosomes
Answer: b [Reason:] Peripheral mesosomes show only a shallow penetration into the cytoplasm, are not restricted to a central location, and are not associated with nuclear material and they are involved in export of exocellular enzymes such as penicillinase.
4. Ribosomes of prokaryotes have a sedimentation coefficient of?
Answer: d [Reason:] Ribosomes of prokaryotes have a sedimentation coefficient of 70S and are composed of two subunits, a 50S and a 30S subunit. But the ribosomes of eukaryotes have a sedimentation coefficient of 80S and are composed of a 60S and a 40S subunit.
5.Poly-beta-hydroxybutyrate(PHB) present in aerobic bacteria can serve as?
a) a reserve carbon and energy source
b) a reserve source of phosphate
c) acceptor of oxygen
d) provides buoyancy
Answer: a [Reason:] A polymer found in aerobic bacteria, especially under high-carbon,low-nitrogen culture conditions, is a chlorofoam-soluble, lipid like material, poly-beta-hydroxybutyrate(PHB), which can serve as a reserve carbon and energy source.
6. Which among the following compound when added to cytoplasmic membrane helps in maintaining the rigidity of cell?
d) amino acids
Answer: b [Reason:] Hopanoids are hydrophobic chemical compounds which when added to cytoplasmic membrane forms a stable and hard compound that helps in maintaining the rigidity of cell.
7. The nucleoid can be made visible under the light microscope by _________
a) Methylene blue
c) Nile blue
d) Feulgen staining
Answer: d [Reason:] Bacteria consist of nucleotide, consisting of a single, circular DNA molecule in which all the genes are linked and it is not a discrete nucleus. The nucleoid can be made visible under the light microscope by Feulgen staining,which is specific for DNA.
8. What helps in the heat resistance of endospore?
a) calcium-DPA complex
Answer: a [Reason:] All endospores contain large amounts of dipicolinic acid (DPA). It occurs in combination with large amounts of calcium and is probably located in the central part of the spore.The calcium-DPA complex play a role in the heat resistance of endospores.
9. Cysts also have high heat resistance like endospores.
Answer: b [Reason:] Cysts are dormant, thick-walled, desiccation-resistant forms that develop by differentiation of a vegetative cell and which can later germinate under suitable conditions. In some ways cysts resemble endospores but they do not have the high heat resistance of endospores.
10. Which of the following methods can be utilized for removing peripheral proteins of the cytoplasmic membrane?
a) treatment by detergents
b) osmotic shock
c) heat application
d) destruction of the membrane
Answer: b [Reason:] Peripheral proteins are loosely attached to cytoplasmic membrane and can be removed by mild treatments such as osmotic shock. On the other hand, integral proteins can be removed only by destruction of the membrane, as with treatment by detergents.
11. Which of the following are true for cytoplasmic membrane?
a) hydrophilic barrier
b) hydrophobic barrier
c) site of generation of protonmotive force
d) hydrophobic barrier and site of generation of protonmotive force
Answer: d [Reason:]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 generation of the proton motive force.
Interview MCQ Set 4
1. Which of the following are mesophilic saprophytes?
Answer: c [Reason:] Bacillus subtilis are mesophilic saprophytes and are widely distributed in nature. This means they can grow best within a temperature range of approximately 25 to 40 degree Celsius.
2. Which of the following causes “milky disease” of Japanese beetle grubs?
Answer: b [Reason:] B.popilliae is a pathogenic species of Bacillus species that causes “milky disease” of Japanese beetle grubs.
3. Which of the following species is associated with spoilage of canned goods?
Answer: a [Reason:] B.stearothermophilus is a thermophilic species having a maximum of 65 to 75 degree Celsius. The endospores are highly resistant to heat and,therefore, this species is one of those associated with spoilage of canned goods.
4. Which of the following genus of species play an active role in the decomposition of urea?
Answer: b [Reason:] Sporosarcinae are widely distributed in fertile soil, where they play active role in the decomposition of urea.
5. C.perfringens is the major causative agent of __________________
c) gas gangrene
Answer: c [Reason:] Clostridium perfringens is the major causative agent of the wound infection known as gas gangrene.
6. Which of the following Clostridium species has the ability to fix Nitrogen?
Answer: b [Reason:] C.pasteurianum is a mesophilic soil clostridium that is particularly noted for its ability to fix Nitrogen.
7. The genus Desulfotomaculum obtain energy by anaerobic respiration.
Answer: a [Reason:] The members of the genus Desulfotomaculum obtain energy by anaerobic respiration, with sulphate serving as the terminal electron acceptor and organic substrates such as lactic or pyruvic acid serving as the electron donors.
8. Pseudomembranous colitis is a disease of _________________
Answer: c [Reason:] C.difficile causes pseudomembranous colitis,a severe disease of the bowel.
9. Bacillus species cannot fix Nitrogen.
Answer: b [Reason:] Bacillus polymyxa has the ability to fix Nitrogen under anaerobic conditions.
Interview MCQ Set 5
1. Translation takes place before transcription.
Answer: b [Reason:] According to central dogma of molecular genetics, the first step is DNA replication, the second is transcription and the last step is translation.
2. Which of the following bacteria can synthesize all of the amino acids required for protein synthesis?
b) Lactobacillus bravis
c) Saccharomyces cerevisiae
d) Bacillus subtilis
Answer: a [Reason:] Microorganisms differ widely in their ability to synthesize amino acids like E.coli can synthesize all of the amino acids required for protein synthesis, whereas lactic acid bacteria cannot.
3. RNAase is a single polypeptide chain of __________ amino acid residues.
Answer: d [Reason:] RNAase is a single polypeptide chain of 124 amino acid residues; it is folded, bent and twisted into a globular shape in its active form.
4 .Protein synthesis in bacteria takes place on which of the following organelles?
a) Endoplasmic Reticulum
b) Golgi body
Answer: c [Reason:] Protein synthesis in bacteria takes place on the ribosomes, which are larger RNA-protein particles in the cytoplasm of the bacterial cell.
5. Which of the following RNA constitutes 90 percent of the total cellular RNA?
Answer: a [Reason:] Ribosomal RNA (rRNA) constitutes about 90 percent of the total cellular RNA and this is important from all other types of RNA.
6. The synthesis of polynucleotide chain of mRNA is catalyzed by the enzyme _____________
a) RNA helicase
b) RNA polymerase
c) DNA polymerase
d) DNA helicase
Answer: b [Reason:] The synthesis of polynucleotide chain of mRNA is catalyzed by the enzyme RNA polymerase. The process in which a single-stranded mRNA is synthesized complementary to one DNA strand is called transcription.
7. Which of the following is responsible for the initiation of RNA polymerase activity?
a) initiation site
b) promoter region
c) sigma factor
d) rho factor
Answer: c [Reason:] In bacteria, the initiation of RNA polymerase activity at the initiation site is due to an initiation factor called the sigma factor, which is a component of the enzyme.
8. Rho factor is a dimeric protein factor.
Answer: b [Reason:] Rho factor is a tetrameric protein factor that binds to RNA polymerase and promotes its termination.When transcription has been completed, rho dissociates from the RNA polymerase-DNA complex.
9. The following code codes for which of the amino acid respectively?
AUG and GUG
Answer: b [Reason:] Three base triplets form a codon which codes for an amino acid.Thus AUG codes for methionine and GUG codes for Valine.AUG and GUG are both initiating codons for translation.
10. Which of the following are non-sense codons?
Answer: c [Reason:] UAA, UAG and UGA are polypeptide-chain-terminating codons and are called non-sense codons.