Microbial Physiology Mock Exam (Microcore)

c. Cells are continuously renewed.

All of the conditions below are present in a chemostat EXCEPT

a. Volume of liquid in growth chamber is maintained constant.

b. Fresh nutrients are continuously supplied.

c. Cells are continuously renewed.

d. One essential nutrient is made limiting.

e. Population density is determined by the removal rate of excess cells through an overflow.

b. Capsule

A thick, compact cover or layer of polymers deposited outside the cell is called

a. Glycocalyx

b. Capsule

c. Slime layer

d. All of the above

e. None of the above

Cells have a constant growth rate.

Which is not a characteristic of the lag phase?

a. Cells are dormant yet physiologically active.

b. There is no increase in cell mass.

c. Cells synthesize new protoplasmic constituents.

d. There is no increase in cell number..

e. Cells have a constant growth rate.

d. Chromosome segregation

All are functions of the cytoplasmic membrane EXCEPT

a. ATP synthesis

b. Response signaling to environment

c. Establishment of electrochemical gradient

d. Chromosome segregation

e. None of the above

c. The domain Archaea later diverged into Eukarya and Archaea.

According to the tree of life based on rRNA genes,

a. The last universal common ancestor (LUCA) is the origin of all life.

b. Evolution from LUCA proceeded along 2 paths to form domains Archaea and Eukarya.

c. The domain Archaea later diverged into Eukarya and Archaea.

d. The domain Eukarya later diverged in Bacteria and Archaea.

e. None of the above

e. Membrane Filter

For direct cell counts, all are used EXCEPT

a. Petroff-Hausser Chamber

b. Hemocytometer

c. Breed Count

d. Coulter Counter

e. Membrane Filter

f. None of the above

d. Penicillin

Which of the following inhibits the translocation step of peptidoglycan synthesis:

a. Phosphonomycin.

b. Bacitracin.

c. Vancomycin.

d. Penicillin.

e. None of the above

e. None of the above

Which is not true about the bacterial cell wall?

a. Gram-positive cell wall possesses a thick peptidoglycan layer.

b. Both Gram-positive and Gram-negative cell walls have a peptidoglycan layer.

c. Both Gram-positive and Gram-negative cell walls have a periplasm.

d. Gram-negative cell wall has an outer membrane.

e. None of the above

Type IV

Which type of pili is involved in twitching motility?

• Type I

• Type IV

• Type F

• Type P

• None of the above

c. If the bacterium was pregrown on a medium containing sugar Y and then inoculated into a medium containing both sugars, the bacteria would utilize (metabolize) sugar Y before sugar X.

Assume that a bacterial culture exhibited a diauxic pattern when growing in a medium containing two different sugars (X and Y). This bacterium grew more rapidly on sugar X than on sugar Y when bacterial growth was measured in a medium containing only one of the sugar substrates. Which of the following statements is not true?

a. Sugar X is the preferred substrate.

b. In the medium containing both substrates, the bacteria synthesized the enzyme needed specifically for metabolism of sugar Y during the diauxic lag phase.

c. If the bacterium was pregrown on a medium containing sugar Y and then inoculated into a medium containing both sugars, the bacteria would utilize (metabolize) sugar Y before sugar X.

d. All of the above

e. None of the above

a. It is a big, soluble, and porous polymer

All are characteristics of peptidoglycan EXCEPT

a. It is a big, soluble, and porous polymer.

b. It is a disaccharide polymer.

c. The glucose residues are connected by β-1,4 linkages.

d. The repeating unit of peptidoglycan is the glycan tetrapeptide.

e. None of the above

d. All of the above

Which step/s is/are involved in lipid synthesis for cell membrane?

a. Binding of fatty acids to sn-glycerol-3-phosphate

b. Fatty acid biosynthesis

c. Production of lipids via conversion of polar head groups.

d. All of the above

e. None of the above

e. None of the above

All are properties of teichoic acids EXCEPT that

a. They bind to calcium ions.

b. They store phosphorus.

c. They facilitate bacteriophage attachment.

d. They are highly antigenic.

e. None of the above

e. None of the above

Which is not true about the assembly of cell membrane proteins?

a. SecB binds to unfolded preprotein.

b. Proteins pass through across the plasma membrane using the translocase.

c. Cell membrane proteins are produced by cytosolic ribosomes

d. A signal peptide is required at the amino terminus.

e. None of the above

f. None of the above

All are alternative forms of motility for bacteria EXCEPT

a. Gliding movement

b. Pilus

c. Axial filaments

d. Rachet structures

e. Contractile cytoskeleton

f. None of the above

e. None of the above

Which is not true regarding the peptidoglycan?

a. Peptide bonds confer strength in the Y direction.

b. In Gram-negative bacteria, the peptidoglycan cross-link is via DAP and D-Ala.

c. In Gram-positive bacteria, the peptidoglycan cross-link occurs though a short peptide interbridge.

d. Glycosidic bonds confer strength in the X direction.

e. None of the above

Rod > Hook > Junction > Filament

The axial proteins involved in flagella synthesis form the axial structure in this order:

a. Basal body > Hook > Junction > Filament

b. Basal body > Junction > Hook > Filament

c. Rod > Hook > Junction > Filament

d. Hook > Rod > Junction > Filament

e. Rings > Junction > Hook > Filament

d. All of the above

The exponential growth of microorganisms depends on the

a. Medium used.

b. Growth conditions.

c. Genotype of the organism.

d. All of the above

e. None of the above

c. It assembles new subunits of flagellum at the tip.

Which of the following does not describe the archaeal flagellum?

a. Unlike its bacterial counterpart, it does not possess a hollow interior.

b. Archaeal flagellin lacks similarity with bacterial flagellin.

c. It assembles new subunits of flagellum at the tip.

d. Its flagellins have signal peptides similar to those of bacterial Type IV pilus.

e. None of the above

d. Methylation of MCP by CheR

In the regulation of chemotaxis, Escherichia coli ignores past stimulus responses by

a. Demethylation of MCP by CheB

b. Autophosphorylation of CheA

c. Binding of CheW to MCP

d. Methylation of MCP by CheR

e. Removal of phosphate from CheA

d. All of the above

What is the purpose of the mesosome?

a. It is involved in DNA replication.

b. It is involved in septum formation.

c. It is involved in cell wall formation.

d. All of the above

e. None of the above

b. Glycan units consist of N-acetyltalosaminuronic acid.

Which is true about the archaeal cell wall?

a. Peptide bridge contains D-amino acids.

b. Glycan units consist of N-acetyltalosaminuronic acid.

c. Glycan units are connected by beta-1,4 bonds.

d. All of the above

e. None of the above

d. Glucose is metabolized first over other carbon sources.

All are characteristics of diauxic growth EXCEPT

a. One carbon source is preferred over the other.

b. One carbon source represses the enzymes required for metabolism of the other carbon source.

c. Several lag phases might be present.

d. Glucose is metabolized first over other carbon sources.

e. None of the above

b. MS ring

In flagellar synthesis, which is synthesized first?

a. P ring

b. MS ring

c. Rod

d. L ring

e. None of the above

b. Protein

What is the most prevalent molecule in the cytoplasm by percent dry weight?

a. Total RNA

b. Protein

c. Phospholipid

d. DNA

e. None of the above

c. CheR

Which protein is responsible for constantly methylating MCP in bacterial chemotaxis?

a. CheA

b. CheY

c. CheR

d. CheB

e. CheB-P

b. It attacks the β-lactam ring.

What is the mode of action of most β-lactamases?

a. It attacks the thiazolidine ring.

b. It attacks the β-lactam ring.

c. It attacks both thiazolidine and β-lactam rings.

d. It modifies the N-acyl group.

e. None of the above

a. It increases the surface area for energy transduction.

What is the purpose of the cytomembrane?

a. It increases the surface area for energy transduction.

b. It is involved in septum formation.

c. It is involved in cell wall formation.

d. It is the storage of ions.

e. None of the above

a. Cause a forward motion.

In most bacteria, a counterclockwise rotation of peritrichous, bundled flagella will

a. Cause a forward motion.

b. Cause a tumbling motion.

c. Stop and reorient the cell.

d. All of the above

e. None of the above

b. Presence of cilia

Which of the following does not describe a prokaryote?

a. Absence of organelles

b. Presence of cilia

c. Presence of a chemically complex cell wall

d. Ribosomes that are either free in the cytoplasm or membrane-bound

e. None of the above

c. Active transport

Of the following transport systems, which require(s) net energy input?

a. Simple diffusion

b. Facilitated diffusion

c. Active transport

d. All of the above

e. None of the above

d. All of the above

Which of the following biomolecules require(s) iron?

a. Cytochromes

b. Nitrogenases

c. Catalases

d. All of the above

e. None of the above

c. Active transport

Which of the following systems allow(s) for transport against a concentration gradient?

a. Facilitated diffusion

b. Simple diffusion

c. Active transport

d. all of the above

e. none of the above

c. ABC transporters

The following transport systems require substrate-binding protein EXCEPT

a. Facilitated diffusion

b. Group translocation

c. ABC transporters

d. All of the above

e. None of the above

d. Purple non-sulfur and Green non-sulfur bacteria

The following groups of organisms can assimilate carbon dioxide as carbon source EXCEPT

a. Algae

b. Cyanobacteria

c. Purple and Green sulfur bacteria

d. Purple non-sulfur and Green non-sulfur bacteria

e. None of the above

c. Boron

Which of the following nutrients is/are NOT considered as macronutrients?

a. Carbon

b. Hydrogen

c. Boron

d. All of the above

e. None of the above

b. Nicotinamide adenine dinucleotide.

All of the following are high energy molecules EXCEPT

a. Adenosine triphosphate.

b. Nicotinamide adenine dinucleotide.

c. Phosphoenolpyruvate.

d. All of the above

e. None of the above

a. ATP synthesis

In bacteria, which of the following processes occurs in/across the cell membrane?

a. ATP synthesis

b. biosynthesis of nucleic acids

c. glycolysis

d. All of the above

e. None of the above

d. Phosphoenolpyruvate

Of the following compounds, which will release the highest free energy upon group transfer:

a. Glucose-6-phosphate

b. ATP

c. Acetyl-phosphate

d. Phosphoenolpyruvate

d. Reaction proceeds with the release of free energy.

A negative Gibbs free energy value denotes that the

a. Reaction is endergonic.

b. Reaction requires energy to proceed.

c. Reaction does not require energy to proceed.

d. Reaction proceeds with the release of free energy.

b. Enzymes affect the energetics or the equilibrium of a reaction

Which of the following is/are FALSE:

a. Enzymes are catalysts that lower the activation energy of a reaction

b. Enzymes affect the energetics or the equilibrium of a reaction

c. Enzymes affect only the rate at which reactions proceed

d. Enzymes are not consumed or transformed by reactions

e. None of the above

c. Redox reaction is an oxidation reaction paired with reduction reaction.

All of the following is FALSE EXCEPT

a. Oxidation is the addition of electrons.

b. Reduction is the removal of electrons.

c. Redox reaction is an oxidation reaction paired with reduction reaction.

d. Oxidation requires oxygen molecules in the reaction.

e. None of the above

a. Oxygen

Which of the following molecules accepts electron most readily?

a. Oxygen

b. Cytochrome

c. Ubiquinone

d. NAD+

e. None of the above

d. NAD+

Which of the following molecules donates electron most readily?

a. Oxygen

b. Cytochrome

c. Ubiquinone

d. NAD+

e. None of the above

e. None of the above

The following major roles are played by adenosine triphosphate EXCEPT

a. It is used as an energy source.

b. ATP can be used to form amide linkages.

c. ATP can be used to form peptide bonds.

d. ATP can be used to form ester bonds.

e. None of the above

e. None of the above

ATP synthesis can happen through the following pathways EXCEPT

a. Oxidative phosphorylation

b. Substrate-level phosphorylation

c. Photophosphorylation

d. Respiratory Chain

e. None of the above

e. None of the above

The following statements are TRUE about Electron Transport Chain (ETC) EXCEPT

a. ETC involves transfer of electrons from the primary electron donor.

b. It mainly occurs in the membrane.

c. It involves series of electron carriers.

d. It is coupled with electrochemical proton gradient generation.

e. None of the above

d. Cytochrome d

Which of the following cytochromes is/are present in Bacteria but is/are absent in mitochondria

a. Cytochrome a

b. Cytochrome b

c. Cytochrome c

d. Cytochrome d

e. None of the above

e. None of the above

Respiratory activity can occur in all the following condition EXCEPT in

a. Aerobic condition.

b. Microaerophilic condition.

c. Anaerobic condition.

d. B and C

e. None of the above

e. None of the above

The following redox molecules are involved in ETC EXCEPT

a. NADH dehydrogenases

b. Flavoproteins

c. Cytochrome c

d. Ferredoxins

e. None of the above

a. carbon dioxide

The following molecules can serve as final electron acceptor in ETC EXCEPT

a. carbon dioxide

b. nitrate

c. nitrite

d. oxygen

e. All of the above

a. NADH dehydrogenases

Which of the following molecules is/are a proton pump

a. NADH dehydrogenases

b. Flavoproteins

c. Cytochrome c

d. Ferredoxins

e. None of the above

a. The carriers are arranged in order of increasingly more negative E0’

All of the following are characteristic features of all electron transport chain EXCEPT

a. The carriers are arranged in order of increasingly more negative E0’.

b. Electron-only and electron-plus-proton carriers alternates in the chain.

c. Net result is reduction of a terminal electron acceptor and generation of PMF.

d. Occurs in the membrane

e. None of the above

b. Ubiquinone

Which of the following carriers shuttles electrons from Complex I to Complex III of ETC?

a. NADH dehydrogenase

b. Ubiquinone

c. Cytochrome

d. Ferredoxin

e. None of the above

b. Ubiquinone

Which of the following carriers shuttles electrons from Complex III to Complex IV?

a. NADH dehydrogenase

b. Ubiquinone

c. Cytochrome

d. Ferredoxin

e. None of the above

b. Ubiquinone

Which of the following carriers can freely move across the membrane?

a. NADH dehydrogenase

b. Ubiquinone

c. Cytochrome

d. Ferredoxin

e. None of the above

b. lactate

For most chemolithotrophs, which is not an electron donor?

a. hydrogen

b. lactate

c. hydrogen sulfide

d. ammonium

e. None of the above

d. Fumarate

For chemolithotrophs, which is NOT an electron acceptor?

a. Sulfur

b. Sulfate

c. Nitrate

d. Fumarate

e. None of the above

e. All of the above

Which of the following molecules is/are common product(s) of all major carbohydrate catabolic pathway?

a. Glucose-6-phosphate

b. Pyruvate

c. Acetyl-CoA

d. Both A and B

e. All of the above

a. Glucose-6-phosphate

Of the following metabolites from glycolysis, which serves as a starting molecule in pentose phosphate pathway?

a. Glucose-6-phosphate

b. Fructose-6-phosphate

c. 1,3-bisphosphoglycerate

d. phosphoenolpyruvate

e. None of the above

e. Both A and C

Which of the following is/are a common precursor molecule for pentose phosphate pathway and Entner-Doudoroff pathway?

a. Glucose-6-phosphate

b. 6-phosphogluconate

c. 2-ketogluconate

d. Both A and B

e. Both A and C

e. Both B and C

Which of the following pathways can be used to catabolize gluconate or gluconic acid?

a. Embden-Meyerhoff-Parnas

b. Pentose Phosphate Pathway

c. Entner-Doudoroff Pathway

d. Both A and B

e. Both B and C

b. Pentose Phosphate Pathway

Which of the following pathways does/do not directly produce ATP?

a. Embden-Meyerhoff-Parnas

b. Pentose Phosphate Pathway

c. Entner-Doudoroff Pathway

d. Both A and B

e. Both B and C

e. Both B and C

Which of the following pathways produce(s) NADPH?

a. Embden-Meyerhoff-Parnas

b. Pentose Phosphate Pathway

c. Entner-Doudoroff Pathway

d. Both A and B

e. Both B and C

a. 2 mol ATP

What is the total (net) ATP yield per mole of glucose via glycolysis alone?

a. 2 mol ATP

b. 4 mol ATP

c. 6 mol ATP

d. 8 mol ATP

e. None of the above

e. None of the above

What is the total (net) ATP yield per mole of glucose via pentos

phosphate pathway alone?

None of the above

What is the total (net) ATP yield per mole of glucose via Entner Doudoroff pathway alone?

a. 2 mol ATP

b. 4 mol ATP

c. 6 mol ATP

d. 8 mol ATP

e. None of the above

c. Pyruvate kinase

Which enzyme is inhibited by PEP through end-product inhibition?

a. Phosphofructokinase

b. Fructose-1,6-biphosphate phosphatase

c. Pyruvate kinase

d. Hexokinase

e. None of the above

e. None of the above

Which is not a primary function of the pentose phosphate pathway?

a. To produce reducing equivalents for reductive biosynthesis

b. To rearrange carbon skeletons of dietary carbohydrates

c. To metabolize dietary pentose sugars derived from nucleic acid digestion

d. To supply the cell with ribose-5-phosphate

e. None of the above

a. Pyruvate

Which is NOT a product of citric acid cycle?

a. Pyruvate

b. Carbon dioxide

c. NADH

d. FADH (reduced)

e. None of the above

b. 15 mol ATP

What is the total (net) ATP yield per mole of pyruvate via citric acid cycle?

a. 10 mol ATP

b. 15 mol ATP

c. 20 mol ATP

d. 30 mol ATP

e. None of the above

d. 38 mol ATP

What is the total (net) ATP yield per mole of glucose via glycolysis plus citric acid cycle?

a. 20 mol ATP

b. 28 mol ATP

c. 34 mol ATP

d. 38 mol ATP

e. None of the above

d. A, B, and C

Which step of the Embden-Meyerhoff-Parnas Pathway is/are irreversible?

a. phosphofructokinase step

b. hexokinase step

c. pyruvate kinase step

d. A, B, and C

e. None of the above

e. None of the above

Which of the following molecules repress(es) Glyoxylate Cycle?

a. Acetate

b. Glucose

c. Pyruvate

d. A, B, and C

e. None of the above

a. Acetate

Which of the following molecules activate(s) Glyoxylate Cycle?

a. Acetate

b. Glucose

c. Pyruvate

d. A, B, and C

e. None of the above

d. A and B

Phosphoenolpyruvate can be derived directly from which molecules?

a. Pyruvate

b. Oxaloacetate

c. Citrate

d. A and B

e. A, B, and C

e. None of the above

Which is NOT an amphibolic pathway?

a. Glycolysis

b. Gluconeogenesis

c. Citric acid cycle

d. Pentose Phosphate Pathway

e. None of the above

e. C and D

Which of the following statements about FERMENTATION is FALSE

a. A form of anaerobic catabolism in which organic compound is both an electron

donor and an electron acceptor

b. Energy (or ATP) generation is mainly by substrate-level phosphorylation

c. Oxygen is not involved in the chemical reactions

d. Fermentation cannot happen in the presence oxygen

e. C and D

f. All of the above

g. None of the above

a. ATP.

Fermentation of pyruvate may result to production of the following molecules EXCEPT

a. ATP.

b. Lactate.

c. Acetate.

d. Ethanol.

e. None of the above

b. Pyruvate

In fermentation, which of the following serves as the primary electron

acceptor?

a. NAD+

b. Pyruvate

c. Acetyl-CoA

d. CO2

e. None of the above

a. Pyruvic acid

Which is NOT a major end-product of mixed acid fermentation?

a. Pyruvic acid

b. Acetate

c. lactate

d. Formate

e. Ethanol

c. Acetone

Which is not a major product of the acidogenic phase of butyrate

fermentation?

a. Butyrate

b. Acetate

c. Acetone

d. H2

e. CO2

b. Acetate

Which is NOT a major product of the solventogenic phase of butyrate

fermentation?

a. Butanol

b. Acetate

c. Acetone

d. Ethanol

e. Isopropanol

e. None of the above

Which is not a product of fermentation?

a. Acetoin

b. Lactate

c. Carbon dioxide

d. Ethanol

e. None of the above

d. NADH

Which is not a product of pyruvate conversion during anaerobic

respiration?

a. acetyl-CoA

b. Carbon dioxide

c. Hydrogen gas

d. NADH

e. Formic acid

b. Pyruvate dehydrogenase

Flavin mononucleotide

Pyruvate dehydrogenase complex requires the following co-factors

EXCEPT

a. Lipoic acid

b. Coenzyme A

c. Nicotinamide adenine dinucleotide

d. Flavin mononucleotide

e. Thymine pyrophosphate

e. All of the above

Lipids are

a. Alternative energy sources.

b. Cell surface components.

c. LPS synthesis carriers.

d. Membrane components.

e. All of the above

f. None of the above

c. Sulfide reduction.

The following are key processes in sulfur cycle EXCEPT

a. Sulfate reduction.

b. Sulfur reduction.

c. Sulfide reduction.

d. Desulfurylation.

e. None of the above

Pyruvate kinase replace pyruvate synthetase

Which of the following is incorrect about the reductive TCA cycle?

a. It is also known as reverse TCA cycle

b. ATP-dependent citrate lyase replaces citrate synthase

c. Pyruvate kinase replace pyruvate synthetase

d. Pyruvate synthase replaces pyruvate dehydrogenase

e. None of the above

e. None of the above

Which statement is NOT true about the Wood-Ljungdahl pathway?

a. It is present in methanogenic archaea as well as acetogens.

b. The acetyl CoA produced can enter the TCA cycle.

c. One and two-carbon intermediates are formed.

d. The enzyme carbon monoxide dehydrogenase needs several metal co-factors for

catalysis.

e. None of the above

b. NADH is oxidized to NAD+ by reduction of FMN to FMNH2 in 2 one-electron steps.

In Complex I of the electron transport chain, electrons are transferred in this manner EXCEPT

a. An electron is transferred from FMNH2 to an Fe-S cluster

b. NADH is oxidized to NAD+ by reduction of FMN to FMNH2 in 2 one-electron

steps.

c. NADH is oxidized to NAD+ by reduction of FMN to FMNH2 in 1 two-electron

steps.

d. An electron is transferred from an Fe-S cluster to ubiquinone.

e. None of the above

None of the above

Which is not true regarding the bacterial and eukaryotic electron

transport systems?

a. Bacterial ETS have four cytochrome types

b. Coupled activity of both bacterial and eukaryotic ETS is through proton

translocation

c. Bacterial and eukaryotic ETS both involve linear flow of electrons

d. O-type heme is only present in bacterial ETS.

e. None of the above

c. Pyruvate or its derivatives serve as electron acceptors.

Which is a unifying characteristic of fermentation?

a. The process requires iron or sulfur proteins.

b. The net gain of fermentation is 2 ATPs.

c. Pyruvate or its derivatives serve as electron acceptors.

d. Hydrogen gas is produced.

e. None of the above

For incorporation of inorganic compounds into organic materials.

Inorganic molecules are used by microorganisms in assimilatory

pathways primarily

a. For incorporation of inorganic compounds into organic materials.

b. As energy and electron source.

c. As electron acceptor.

d. As energy source

e. None of the above

e. A and C

In acetogenesis, acetate can be produced from

a. Acetyl-CoA

b. Folic acid

c. Carbon dioxide

d. A and B

e. A and C

e. A and C

In acetogenesis, acetate can be produced from

a. Acetyl-CoA

b. Folic acid

c. Carbon dioxide

d. A and B

e. A and C

b. Oxidation of reduced inorganic sulfur compounds

The main purpose of the Sox system is for

a. Reduction of oxidized inorganic sulfur compounds

b. Oxidation of reduced inorganic sulfur compounds

c. Reduction of oxidized organic sulfur compounds

d. Oxidation of reduced organic sulfur compounds

e. None of the above

e. None of the above

Which of the following is NOT TRUE about “Proton Current” across the membrane

a. Protons are translocated to the cell surface, driven there by either chemical or

light energy through a proton pump.

b. Protons are returned through special proton transporters.

c. The accumulation of protons on the outside surface of the membrane

establishes a membrane potential.

d. A pH gradient can also be established.

e. None of the above

c. High energy requiring

Which is NOT a characteristic of membrane transport systems

a. Show a saturation effect.

b. High specificity

c. High energy requiring

d. Highly-regulated

e. None of the above