Interview MCQ Set 1
1. The TCA Cycle is an _____________ pathway.
Answer: c [Reason:] The TCA cycle is an amphibolic cycle which means that it functions not only in catabolic (breakdown) but also in anabolic (synthesis) reactions.
2. Which of the following intermediates of TCA cycle act as amino acid precursors?
a) oxaloacetic acid
b) succinic acid
c) citric acid
d) acetyl CoA
Answer: a [Reason:] Oxaloacetic acid and alpha-ketoglutaric acid are some of the intermediates of TCA cycle which act as amino acid precursors.Oxaloacetate forms aspartate which then gives us lysine and threonine.
3. Which pathway will result in the production of four carbon dioxide molecules, two ATP molecules, NADH2 and FADH2?
b) Krebs cycle
c) Calvin cycle
d) electron transport system
Answer: b [Reason:] Krebs Cycle is another name for TCA cycle whose overall reaction is as follows:
2Acetyl CoA+ 3H2O + 3NAD+ + FAD+ ADP+ Pi———> 4CO2+ 2CoA+ 2NADH2+ 2FADH2+ ATP.
4. The TCA cycle is regulated by which of the following enzymes?
a) citrate synthase
b) isocitrate dehydrogenase
c) malate dehydrogenase
d) succinate dehydrogenase
Answer: b [Reason:] TCA cycle is regulated by the enzyme isocitrate dehydrogenase which is sensitive to feedback inhibition by high concentration of ATP and NADH2 and stimulation by high concentration of ADP and NAD.
5. Protein molecules can easily pass into the cell for being utilized for energy production.
Answer: b [Reason:] Protein molecules are too large to pass into the cell, bacteria secrete exoenzymes called proteases that hydrolyze exogenous proteins to peptides, which are then transported into the cell cytoplasm.
6. Which of the following pathway is common for oxidation of carbohydrates, lipids and amino acids?
a) Calvin cycle
b) Electron transport chain
c) TCA cycle
d) Pentose phosphate pathway
Answer: c [Reason:] Since acetyl-CoA is a common intermediate of carbohydrate, lipid, and amino acid metabolism so it enters the TCA cycle and hence TCA cycle is a common pathway for oxidation of carbohydrates, lipids and amino acids.
7. Phosphoenolpyruvate (PEP) is converted to oxaloacetate by the enzyme PEP deaminase.
Answer: b [Reason:] PEP is converted to oxaloacetate by the enzyme PEP carboxylase. This is a type of carbon dioxide fixing reaction.
8. The enzymes present in glyoxylate cycle are which type of enzymes?
a) reductase enzymes
b) anaplerotic enzymes
c) transferase enzymes
d) hydrolase enzymes
Answer: b [Reason:] The specific enzymes for glyoxalate cycle are isocitrate lyase and malate synthase which carry out replenishment of the pool of intermediates of the TCA cycle and hence are known as anaplerotic enzymes.
9. Which molecule will combine with the four-carbon oxaloacetate in the TCA cycle to form the six-carbon citrate?
a) lactic acid
Answer: d [Reason:] The first step of the TCA cycle is the reaction between oxaloacetate and acetyl-CoA to form citrate. This acetyl-CoA comes from carbohydrate, lipid metabolism.
10. The number of ATP molecules generated in TCA cycle is _________
Answer: c [Reason:] In TCA cycle the following result is obtained:
6 NADH2 —> 18 ATP
2 FADH2 —> 4 ATP
2 GTP —> 2 ATP
Thus, total ATP = 24 ATP.
Interview MCQ Set 2
1. Which of the following acts as chemical reductant in bacterial photosynthesis?
c) hydrogen sulphide
Answer: c [Reason:] Bacteria that performs photosynthesis utilises inorganic compound H2S or organic compounds as chemical reductant instead of water.
2. The region in which bacteriochlorophyll can absorb light is _________
a) ultraviolet region
b) infrared region
c) visible region
d) microwave region
Answer: b [Reason:] Anoxygenic photosynthetic bacteria possess bacteriochlorophyll which absorb light in the infrared region (725 to 1035 nm).
3. Where are bacteriochlorophyll present in the cell?
Answer: d [Reason:] Bacteriochlorophyll are not contained in the chloroplasts but are found in extensive membrane systems like the cytoplasmic membrane throughout the bacterial cell.
4. Which of the following steps during electron transfer in anoxygenic photosynthesis is the ATP production step?
a) Ferredoxin to ubiquinone
b) ubiquinone to cyt b
c) cyt b to cyt f
d) cyt f to excited bacteriochlorophyll
Answer: c [Reason:] The energy released in electron transfer between cytochrome b and cytochrome f is used for photophosphorylation i.e., the generation of ATP from ADP and inorganic phosphate.
5. An essential process connected with photosynthesis is
b) synthesis of glucose
d) electron transfer
Answer: a [Reason:] In cyclic photophosphorylation electron lost by pigment system II is not cycled back instead they are replaced by the light-generated breakdown of water, called photolysis.
6. Purple Sulphur Bacteria contains bacteriochlorophyll b and bacteriochlorophyll c
Answer: b [Reason:] Purple Sulphur bacteria contains bacteriochlorophyll a and bacteriochlorophyll b and it utilizes sulphur containing compound as chemical reductant.
7. Chlorobium sp. is which type of bacteria?
a) Purple Sulphur Bacteria
b) Purple Non-sulphur Bacteria
c) Green Sulphur bacteria
d) Green Non-sulphur bacteria
Answer: c [Reason:] Chlorobium sp. is a Green sulphur bacteria that contains bacteriochlorophyll c and d and utilizes sulphur as chemical reductant in photosynthesis.
8. RuBisCO enzyme plays an important role in __________
a) light phase
b) dark phase
c) electron transport chain
d) TCA cycle
Answer: b [Reason:] All the enzymatic reactions take place in the dark phase which does not depend on light.RuBisCO helps in the reaction between RuBP and carbon dioxide to form 3-phosphoglycerate.
9. The final product of Calvin cycle is _________
c) Dihydroxy acetone phosphate
Answer: d [Reason:] Glyceraldehyde-3-phosphate is the final product of Calvin cycle which again regenerates RuBP.
10. The dark reaction in photosynthesis is governed by __________
a) CO2, temperature, and light
b) CO2, light, and water
c) water, temperature, and CO2
d) oxygen, water, and temperature
Answer: a [Reason:] The dark reaction does not require light and involves reduction of carbon dioxide to yield glyeraldehyde-3-phosphate.
Interview MCQ Set 3
1. Which of the following toxins cause damage to the tissue cells by its phospholipase action?
a) alpha toxin
b) delta toxin
c) protein A
Answer: b [Reason:] Delta toxin damages tissue cells by its action as a phospholipase. It is produced by human strains of S. aureus.
2. Which of the following microorganism causes lesions in the form of abscesses?
a) Staphylococcus aureus
b) Streptococcus pyogenes
c) Streptococcus pneumoniae
d) Clostridium perfringens
Answer: a [Reason:] Staphylococcus aureus causes localized infections in which the characteristic lesion is a walled-off fort called the abscess— a cavity filled with pus cells (neutrophils), dead tissue, and bacteria.
3. Antibiotics can easily reach the staphylococci.
Answer: b [Reason:] Antibiotics have a difficulty in reaching the staphylococci and may have to be administered to a patient for a long period in order to be effective.
4. Streptococus pyogenes comprises which Lancefield group?
Answer: a [Reason:] Streptococus pyogenes comprises Lancefield group A. This organism causes several diseases like sore throat, scarlet fever etc.
5. Which of the following microbe does not belong to Group D enterococci group?
a) S. faecalis
b) S. faecium
c) S. durans
d) S. bovis
Answer: d [Reason:] S. bovis belongs to Group D nonenterococci group. All other above microbes belong to Group D enterococci group.
6. Scarlet fever is similar to the pharyngitis in all respects.
Answer: b [Reason:] Scarlet fever is similar to the pharyngitis except for the skin rash that appears because of the erythrogenic toxin.
7. Which of the following immunity is protective against infection by S.pyogenes?
a) cell-mediated immunity
b) antigen-antibody immunity
c) humoral immunity
d) no cure present
Answer: c [Reason:] The only type of immunity that is protective against infection by S. pyogenes is humoral immunity: antibodies against M proteins act as opsonins, enhancing phagocytosis of the streptococci.
8. Puerperal fever is a streptococcal infection of the ______________
Answer: c [Reason:] Puerperal fever, sometimes called puerperal sepsis, is a streptococcal infection of the uterus of a mother and is acquired at childbirth.
9. Which of the following is a major virulence factor of Streptococcus pneumoniae?
a) polysaccharide capsule
b) M protein
c) streptolysin O
d) streptolysin S
Answer: a [Reason:] The major virulence factor is the polysaccharide capsule, which effectively inhibits phagocytosis.
10. Which drug is used for treatment of anthrax?
Answer: b [Reason:] Penicillin is the drug of choice for treatment of anthrax. A live attenuated vaccine is available for prevention of anthrax in cattle and sheep.
Interview MCQ Set 4
1. Which of the following has no detectable ATPase activity?
b) eukaryotic flagella
c) bacterial flagella
Answer: c [Reason:] 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?
b) protonmotive force
d) water gradient
Answer: b [Reason:] 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 [Reason:] 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.
Answer: b [Reason:] In passive diffusion no substance in the membrane interacts specifically with the solute molecules. The difference in concentration gradient governs the rate of 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 [Reason:] 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 [Reason:] Porter or permease is a specific protein carrier molecule which 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.
Answer: a [Reason:] 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?
Answer: a [Reason:] 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 [Reason:] 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
Answer: b [Reason:] 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 _____________
b) Salmonella typhimurium
c) Saccharomyces cerevisiae
Answer: a [Reason:] Mannitol enzyme II has been purified from E.coli. Other enzymes can be purified from several other bacteria.
Interview MCQ Set 5
1. The cell diameter of bacteria belonging to family Enterobacteriaceae is ____________
a) 1 m
b) 1 cm
c) .3-1.5 micrometre
d) 5 micrometre
Answer: c [Reason:] A distinctive feature of the family Enterobacteriaceae is that the cell diameter is 0.3 to 1.5 micrometer.
2. What is the cell shape of the organisms belonging to the family Enterobacteriaceae?
d) straight rod
Answer: d [Reason:] The cell shape of organisms belonging to the family Enterobacteriaceae is that of a straight rod.
3. Enterobacteriaceae possesses endoflagella.
Answer: b [Reason:] Enterobacteriaceae possesses lateral flagella and moves by means of it. It does not possess endoflagella.
4. Which of the following genus of bacteria causes gastroenteritis in humans?
Answer: c [Reason:] Some bacteria of genus Escherichia causes gastroenteritis and some others can also cause urinary tract infections.
5. Enterobacter sp. gives negative result for Voges-Proskauer test.
Answer: b [Reason:] Enterobacter sp. gives positive result for Voges-Proskauer test by giving a reddish-pink colouration.
6. Which of the following genus of bacteria under the family Enterobacteriaceae is mainly associated with plants?
Answer: a [Reason:] Bacteria belonging to the genus Erwinia differ from most other Enterobacteriaceae by being mainly associated with plants.They are often plant pathogens, causing diseases such as blights,leaf spot, wilts etc.
7. Which of the following is the causative agent of plague?
Answer: b [Reason:] Yersiniae are parasites of animals but can also cause infections in humans.For example, Y.pestis is the causative agent of plague.
8. The family Vibrionaceae is _________________
c) coccus shaped
Answer: a [Reason:] A distinctive feature of the family Vibrionaceae is that they are usually oxidase-positive.They are motile by means of polar flagella and cell shape is that of curved or straight rods.
9. Which of the following genus shows the characteristic of bioluminescence?
Answer: c [Reason:] Some species of genus Vibrio can emit light of a blue-green color(bioluminescence), an oxygen-dependent reaction catalyzed by the enzyme luciferase.
10. Among the given families, which family contains organisms that are non-motile?
Answer: d [Reason:] Pasteurellaceae contains cells that are nonmotile.Their cell diameter is very small and the shape is that of a straight rod.
11. The X factor and/or the V factor is required by which genus of bacteria?
Answer: b [Reason:] Haemophilus bacteria is distinguished by unusual nutritional requirements: the X factor (heme, occurring in blood) and/or the V factor( the coenzyme nicotinamide adenine dinucleotide).