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WorksheetsMicrobial Metabolism P5
Total questions: 89
Worksheet time: 47mins
Which statement about enzymes is correct?
Enzymes increase the reaction rate
Enzymes are consumed during the reaction and need to be replenished
Enzymes need metals to work
Enzymes can turn an endergonic reaction to an exergonic reaction
When the redox potential of a compound is below zero, it acts as electron donor.
True
False
Chemoorganotrophs and chemolithotrophs differ in their...
energy source
electron acceptor
affinity to light
affinity to electrons
An exergonic reaction has a negative deltaG
True
False
There are two types of cofactors. Those that are covalently/tightly bound are called
______
and those that are non-covalently bound and interact with different enzymes are called
______
(a)
Who is growing faster?
(A) Ammonium + oxygen -> nitrite, deltaG0' -280 kJ/mol
(B) Ammonium + nitrite -> nitrogen gas, deltaG0' -340 kJ/mol
A is growing quicker
B is growing quicker
You cannot tell from the deltaG0' values
They are growing at the same speed
What is the first law of thermodynamics?
Energy can be generated only by microorganisms, not by plants/animals
Energy is only generated by phototrophs, not by chemotrophs
Energy can be transformed from one form to another but not been generated or destroyed
The prime in E zero prime (E0') denotes biological instead of chemical conditions (pH 7.0, 25 degree centigrade).
True
False
Oxidoreductases do not require prosthetic groups.
True
False
The eventual objective of catabolism is:
the biosynthesis of biomolecules such as amino acids and DNA precursors
the fixation of CO2 into biomass
the breakdown of organic molecules to inorganic molecules
the production of ATP for locomotion and growth
According to the first law of thermodynamics, energy can only be imported, not produced
True
False
The redox potential of the NAD+/NADH couple is -320 mV, the redox potential of the fumarate/succinate couple is +30 mV. Please calculate the redox potential difference (DeltaE0') of NADH-dependent fumarate reduction!
(a)
Catabolism describes energy releasing metabolic reactions
True
False
Lactic acid bacteria produce lactic acid from pyruvate
True
False
Which statement about NADH/NAD+ is correct?
The cellular pool of NADH/NAD+ is small compared to the energy source glucose
NAD+ is an electron donor
NAD stands for Niacinaldehydedihydroorotate
All chemoorganotrophs are aerobes
True
False
Glycolysis is the process of...
degrading glucose to CO2
degrading glucose to pyruvate
respiring glucose with oxygen
Glycolysis consumes 2 ATP and produces 4 ATP, so there is a net gain of 2 ATP
True
False
Phosphoenolpyruvate can directly phosphorylate ADP to ATP in a process called substrate level phosphorylation
True
False
NADH can directly phosphorylate ATP
True
False
Which statement about ATP and NADH is correct?
Both ADP and NAD+ need to be recycled during microbial metabolism
Glycolysis requires more ATP than it produces
ATP and NADH are both electron carriers
Glycolysis is a net NADH consuming process
Does glycolysis require oxygen?
Only stage II of glycolysis is anaerobic
Stage I and II of glycolysis are anaerobic
Only stage I of glycolysis is anaerobic
Stage I and II of glycolysis are aerobic
ATP hydrolysis to ADP + Pi or AMP + PPi yield the same amount of energy, -31 kJ/mol
True
False
Which statement about aerobic respiration is correct?
Aerobic respiration can also occur without oxygen
Aerobic respiration gains energy via substrate level phosphorylation
Aerobic respiration oxidizes NADH and reduces O2
Aerobic respiration conserves energy via chemiosmosis
True
False
Membrane bound enzymes are required for chemiosmosis
True
False
Proton motive force is generated by ATP synthase
True
False
The citric acid cycle couples acetyl-CoA to oxaloacetate
True
False
Chemoorganotrophs require as electron donor...
water
inorganic chemicals
organic chemicals
light
Aerobic respiration uses a respiratory chain to oxidize NADH and reduce water
True
False
Substrate-level phosphorylation depends on...
direct phosphorylation of ADP
the buildup of a proton motive force
The membrane potential delta psi is built up of
equally the pH and charge gradient
mainly the charge gradient
mainly the pH gradient
Which of the following enzymes is NOT involved in the aerobic respiratory chain?
nitrate reductase
cytochrome bc complex
NADH dehydrogenase
cytochrome oxidase
Succinate dehydrogenase is involved in the TCA cycle and the aerobic respiratory chain.
True
False
Which statement about the TCA cycle is correct?
The main reason of running the TCA cycle is to produce ATP by substrate level phosphorylation
The NADH produced during the TCA cycle is used for fermentation
In the TCA cycle, several decarboxylating steps happen, releasing CO2
Which statement about sulfate respiration is correct?
Sulfate respiration uses organic and inorganic electron donors
Sulfate respiration is energetically very favorable
Sulfate respiration conserves energy only by substrate level phosphorylation
Anaerobic respiration requires membrane-bound enzymes.
True
False
Which of the following can NOT be a final product of nitrate respiration?
hydroxylamine (NH2OH)
ammonium (NH4+)
molecular nitrogen (N2)
nitrite (NO2-)
Sulfate reduction requires sulfate to be activated by ATP
True
False
The thermodynamic hierarchy predicts that anaerobic respiration is preferred over aerobic respiration.
False
True
Which of the following are habitats for sulfate reducing bacteria?
Marine sediments
Agricultural fields
The human gut
Which statement about anaerobic respiration is correct?
Anaerobic respiration requires O2 as electron acceptor
Anaerobic respiration is restricted to chemoorganotrophs
Anaerobic respiration uses electron transport phosphorylation
Anaerobic respiration always requires nitrate
Denitrification uses sulfate as terminal electron acceptor.
True
False
Dissimilatory nitrate reduction to ammonium uses ammonium as electron donor
True
False
Anaerobic respiration happens in the presence of oxygen.
True
False
Methyl-CoM reductase produces methane from CH3-CoM
True
False
Syntrophy is the metabolic competition for the same substrate
True
False
Acetogens use the Wood-Ljungdahl pathway for acetate production
True
False
Acetoclastic methanogens conserve energy via substrate level phosphorylation
True
False
Hydrogenotrophic methanogens produce methane from H2+acetate
True
False
Which statement about methanogens is correct?
Some methanogens, but not all, are archaea
Methanogens contain hydrogenases for H2 oxidation
Lactate is a substrate of methanogens
Anaerobic methane oxidation with sulfate...
Is performed by a single archaeon
Is performed by a syntrophic consortium
Does not involve archaea
Please indicate which substrates CANNOT directly be used by non-syntrophic methanogens!
methylamines
propionate
acetate
H2+CO2
Anaerobic methanotrophic archaea possess methyl-CoM reductase
True
False
Acetogens use both substrate level phosphorylation and chemiosmosis for ATP generation
True
False
Which statement about acetogens and the Wood-Ljungdahl pathway is correct?
The key enzyme of the Wood-Ljungdahl pathway is CO dehydrogenase/acetyl-CoA synthase
The methyl branch of the Wood-Ljungdahl pathway produces carrier-bound CO
The carbonyl branch uses tetrahydrofolate as C carrier
Acetogens are aerobes
Biosynthetic pathways can also be named assimilatory pathways or anabolism
True
False
Which statement about amino acids and peptides is correct?
Not all amino acids contain an amino group
In an alpha-helix the secondary structure is initiated by hdyrogen bonds whereas beta sheets make use of covalent linkages
A polypeptide has a C and an N terminus
Transaminase catalyzes the reaction of ammonium with alpha-ketoglutarate to yield glutamate
True
False
Ammonium, nitrate and N2 can all directly be incorporated into amino acids through transaminase reactions
True
False
Which is an unwanted side product of the nitrogenase reaction, and why?
N2, because nitrogen fixation requires ammonium as a substrate
Ammonium, because it takes 8 ATP per produced molecule
Hydrogen, because it uses up reducing power without yielding ammonium
ATP, because the cell would rather not invest ATP
The nitrogenase reaction requires N2, ATP and oxygen
True
False
Nitrogen is lost from the environment through nitrogen fixation
True
False
How is the cellular compartment called that enables N2 fixation in aerobic cyanobacteria?
(a)
Root nodule symbiosis is used for
Nitrogen fixation and photosynthesis
Nitrogen fixation only
Nitrogen and carbon fixation
Photosynthesis only
Rhizobacteria form bacteroids in plant root cells after invading root hairs.
True
False
The bacteroid provides C4 sugars for the plant
False
True
What is the function of leghemoglobin?
To protect nitrogenase from oxygen and supply oxygen to the bacterial electron transport chain
To make the bacteroids completely anoxic
To supply oxygen from the bacteroid to the plant
Which statement about chemolithotrophs is correct?
Chemolithotrophs use organic compounds as their carbon source
Chemolithotrophs are always aerobic
Chemolithotrophs use inorganic chemicals as electron donors
Chemolithotrophs produce oxygen
Deep sea ecosystems are fuelled by photosynthesis
True
False
Which properties do the symbiotic bacteria of giant tube worm Riftia pachyptila possess?
They oxidize sulfide and reduce oxygen, in order to obtain energy for CO2 fixation
The worm lives off the ingestion of sulfide oxidizing bacteria
They extract organic materials from the worm to make a living
The bacteria are anaerobes and perform anaerobic respiration
The key enzyme of sulfide oxidation, DsrAB, is also used during sulfate respiration
True
False
The key enzyme of hydrogen-oxidizing bacteria is called
(a)
Which processes contribute to nitrification?
Nitrite oxidation
Ammonia oxidation
Complete ammonia oxidation (Comammox)
Denitrification
Dissimilatory nitrogen reduction to ammonium
During crop fertilization, ammonia oxidation to nitrite and nitrate are desired processes
False
True
Which is/are the key enzyme(s) of the comammox reaction
Ammonia monooxygenase and nitrite oxidorectuctase
Hydrazine synthase and hydrazine dehydrogenase
Ammonia monooxygenase
Nitrite oxidoreductase
Nitrifying microorganisms require reverse electron transport because the redox potential of their electron donors is too high to reduce NAD+ to NADH directly
True
False
Reverse electron transport produces NADH from quinol.
True
False
The Calvin cycle requires NADPH, but not ATP, to fix CO2
False
True
Which is the key enzyme of the Calvin cycle?
Methyl-CoM reductase
Ribulose-1,5-bisphosphate carboxylase oxygenase
Fructose aldolase
Acetyl-Co synthetase
In purple bacterial photosynthesis, electrons travel in a Z scheme.
False
True
The cyt b6f complex is part of a respiratory chain
True
False
Reverse electron flow is necessary...
to supply reducing power for CO2 fixation
for ATP production through photophosphorylation
as electron donor for photosynthesis
Carotenoids protect from light damage
True
False
Which statement about the chemical properties of bacteriochlorophyll is correct?
absorbs blue light
It contains Mg in its active site
It is a cytochrome
H2S is an electron donor for photosynthetic CO2 fixation.
True
False
Chlorophyll absorbs green light.
False
True
The function of light harvesting complexes is
to direct more light to the reaction centers
to protect from too much light
to give phototrophs pretty colors
What is the color of bacteriochlorophyll a?
Blue
Green
Yellow
Red
