Microbiology Chapter 6

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Experiments designed by ______________ suggested that living cells caused the fermentation of sugar to produce alcohol.
Pasteur
Koch
Wohler
Fleming

Pasteur

Studies done by Buchner showed that ground-up yeast cells were able to convert sugar to alcohol. The components of the mixture that were responsible for this transformation were
DNA molecules.
enzymes.
lipids.
carbohydrates.

enzymes

Concerning catabolism and anabolism,
they refer to reactions solely dealing with the metabolism of lipids.
the intermediates of one serve as the reactants in the other.
the energy gathered in one is utilized in the other.
they refer solely to the reactions involved in synthesis of carbohydrates.
the intermediates of one serve as the reactants in the other AND the energy gathered in one is utilized in the other.

the intermediates of one serve as the reactants in the other AND the energy gathered in one is utilized in the other.

The general term used to describe the anabolic and catabolic reactions in a cell is
enzymatic.
thematic.
aerobic respiration.
metabolism.

metabolism

Energy is defined as
water flowing up a dam.
the capacity to do work.
the use of high level phosphate bonds.
the potential to fall.

the capacity to do work

Biosynthetic reactions that require energy for the conversion of molecular subunits into larger molecules are called
kinetic energy.
catabolic reactions.
precursor molecules.
anabolic reactions.

anabolic reactions

Exergonic reactions
occur when there is more free energy in the products than the reactants.
occur when there is more free energy in the reactants than the products.
are defined as a decrease in entropy.
are chemoorganotrophic.

occur when there is more free energy in the reactants than the products.

Free energy
includes the energy lost as heat.
is the amount of energy gained by breaking bonds of a chemical.
differs for a given reaction depending on the number of steps involved.
always results in a decrease in total energy.
is the amount of energy gained by breaking bonds of a chemical AND differs for a given reaction depending on the number of steps involved.

is the amount of energy gained by breaking bonds of a chemical.

Bacteria that can absorb light energy and convert it into ATP are commonly called
cytochromes.
lysosomes.
chemotrophs.
phototrophs.
cytochromes AND chemotrophs.

phototrophs

The readily usable energy currency of cells is
electricity.
the electron transport system.
ATP.
CTP.
the electron transport system AND CTP.

ATP

Each of the following statements about chemoorganotrophs is true EXCEPT:
They may use substrate-level phosphorylation to produce ATP.
They may use oxidative phosphorylation to produce ATP.
They may use photophosporylation to produce ATP.
They utilize an electrochemical gradient.

They may use photophosporylation to produce ATP.

The name given to the reaction involving removal of electrons or hydrogen atoms from a compound is termed
glycolysis.
reduction.
oxidation.
metabolism.

oxidation

The name given to the reaction involving addition of electrons or hydrogen atoms to a compound is termed
glycolysis.
reduction.
oxidation.
metabolism.

reduction

NAD in its reduced form is symbolized as
NADH.
NAD.
NAD-.
NADP.

NADH

Glycolysis
is also known as the Embden-Meyerhof-Parnas pathway.
is also known as the Entner-Duodoroff pathway.
is used by Pseudomonas and a few other bacteria.
generates some energy and NADPH.
is also known as the Entner-Duodoroff pathway AND is used by Pseudomonas and a few other bacteria.

is also known as the Embden-Meyerhof-Parnas pathway.

The most common starting pathway for the breakdown of sugars is
respiration.
fermentation.
glycolysis.
oxidation.

glycolysis

Glycolysis produces
pyruvate.
NAD.
NADP.
acetyl-CoA.

pyruvate

Cells degrade sugar largely to
gain energy.
use energy.
convert fat to energy.
utilize coenzymes.

gain energy

Oxygen serves as the terminal electron acceptor in
fermentation.
aerobic respiration.
anaerobic respiration.
reduction.

aerobic respiration

The terminal electron acceptor in respiration may be
oxygen.
nitrate.
NAD.
an inorganic molecule.
oxygen, nitrate AND an inorganic molecule.

oxygen, nitrate AND an inorganic molecule.

Which of the following processes generates the greatest amount of energy?
fermentation
aerobic respiration
the Entner-Duodoroff pathway
glycolysis
fermentation AND the Entner-Duodoroff pathway

aerobic respiration

Fermentation
uses an inorganic molecule as the final electron acceptor.
uses an organic molecule as the final electron acceptor.
results in the production of a large amount of ATP.
is necessary in some organisms to produce reduced electron carriers.
uses an organic molecule as the final electron acceptor AND is necessary in some organisms to produce reduced electron carriers.

uses an organic molecule as the final electron acceptor.

Which is/are true regarding organic acids?
They are weak acids.
They are often involved in metabolic reactions.
They often exist in the ionized form at the near-neutral pH found in a cell.
Pyruvate and pyruvic acid refer to different forms of the same substance.
All of the choices are true.

All of the choices are true.

Pyruvate can be metabolized along two major routes. They are
oxidation and reduction.
fermentation and respiration.
metabolism and anabolism.
anabolism and catabolism.

fermentation and respiration

The use of the suffix "ase" on a word denotes a(n)
substrate.
product.
enzyme.
electron acceptor.
substrate AND electron acceptor.

enzyme

Enzymes act as
substrates.
catalysts.
products.
catabolites.

catalysts

Enzymes act on _______ to produce ________.
products, catabolites
substrates, products
products, substrates
glucose, anabolites

substrates, products

Enzymes speed up reactions by
raising activation energy.
producing heat.
reducing entropy.
lowering activation energy.
raising activation energy AND reducing entropy.

lowering activation energy

The mutual interaction of substrate and enzyme is described as a(n)
lock and key arrangement.
induced fit.
active site.
allosteric site.
active site AND allosteric site.

induced fit

Most enzymes
are generalists and typically recognize a number of different substrates.
are specialists and typically recognize a single substrate.
are active over a wide pH range.
have several active sites.
are generalists and typically recognize a number of different substrates AND have several active sites.

are specialists and typically recognize a single substrate.

Allosteric enzymes
may bind two substrates.
are used to bind to other enzymes.
have an additional binding site that is involved in regulating enzyme activity.
are twice as fast as single site enzymes.
may bind two substrates AND are twice as fast as single site enzymes.

have an additional binding site that is involved in regulating enzyme activity.

Feedback inhibition
is a means of regulating the amount of product produced.
often involves the use of allosteric enzymes.
involves inhibiting the last of a series of reactions.
results in raising the activation energy for the reaction.
is a means of regulating the amount of product produced AND often involves the use of allosteric enzymes.

is a means of regulating the amount of product produced AND often involves the use of allosteric enzymes.

Coenzymes are derivatives of
minerals.
proteins.
lipids.
vitamins.

vitamins

The small, non-protein molecules that can be readily separated from an enzyme and are responsible for transfer of atoms from one molecule to another are referred to as
vitamins.
enzymes.
hormones.
coenzymes.

coenzymes

Which is/are true of coenzymes?
They are organic molecules.
They transfer atoms from one molecule to another.
They may bind to a number of different enzymes.
They are synthesized from vitamins.
All of the choices are correct.

All of the choices are correct

Environmental factors that may affect enzyme activity include
temperature
pH
salt
age
temperature, pH AND salt

temperature, pH AND salt

Most enzymes function best at
acidic pH and high salt concentrations.
basic pH and low salt concentrations.
neutral pH and high salt concentrations.
slightly above pH 7 and low salt concentrations.

slightly above pH 7 and low salt concentrations.

Which is true of competitive inhibition?
It involves an allosteric enzyme.
Substrate and inhibitor both bind to the active site.
PABA (para-aminobenzoic acid) is a competitive inhibitor.
Mercury is a competitive inhibitor.
Substrate and inhibitor both bind to the active site AND PABA (para-aminobenzoic acid) is a competitive inhibitor.

Substrate and inhibitor both bind to the active site AND PABA (para-aminobenzoic acid) is a competitive inhibitor.

The term precursor metabolite refers to molecules that
activate cell components.
are used in biosynthesis.
result from cell activities.
are present but inactive.

are used in biosynthesis

Which is true regarding the three central metabolic pathways?
They form high energy bonds that can be used to synthesize ATP.
They form intermediates that can be oxidized to generate reducing power.
They form precursor metabolites.
All of the choices are correct.

All of the choices are correct.

Glycolysis
requires oxygen.
produces 3 ATP molecules.
produces 4 molecules of NAD.
may occur under aerobic or anaerobic conditions.
produces 3 ATP molecules AND produces 4 molecules of NAD.

may occur under aerobic or anaerobic conditions.

The energy yield of any energy-transforming pathway
is fixed.
is variable depending on the type of enzymes used.
is variable depending on the amount of precursor metabolites removed for biosynthesis.
is fixed by the amount of oxygen available.

is variable depending on the amount of precursor metabolites removed for biosynthesis.

The transition step
links glycolysis to the pentose phosphate pathway.
links the pentose phosphate pathway to the Entner-Duodoroff pathway.
links glycolysis to the TCA cycle.
takes place in the matrix of the nucleus.

links glycolysis to the TCA cycle.

The TCA cycle produces
ATP through substrate-level phosphorylation.
NADH.
FADH2.
precursor metabolites.
All of the choices are correct.

All of the choices are correct

What happens to the carbon molecules in the pyruvic acid that goes through the TCA cycle?
They get incorporated into cell material.
They are excreted as waste organic acids.
They become carbon dioxide.
They form "energy storage molecules" and are stored by the cell.

They become carbon dioxide

The electron transport system
requires a membrane.
utilizes the nuclear membrane of eukaryotes.
utilizes the mitochondrial membrane of prokaryotes.
generates a concentration gradient of protons.
requires a membrane AND generates a concentration gradient of protons.

requires a membrane AND generates a concentration gradient of protons.

Which type of phosphorylation does not require a membrane?
Substrate-level phosphorylation
Oxidative phosphorylation
Photophosphorylation
All types of phosphorylation require a membrane.

Substrate-level phosphorylation

In the electron transport system
NADH and FADH2 both donate electrons at the same location.
NADH donates electrons "upstream" of where FADH2 donates electrons.
NAD donates electrons at the head of the chain.
NADP donates electrons in the middle of the chain.

NADH donates electrons "upstream" of where FADH2 donates electrons.

Proton motive force
is used to synthesize ATP.
is used to drive flagella rotation.
is used to produce NADH.
is used to produce FADH2.
is used to synthesize ATP AND is used to drive flagella rotation.

is used to synthesize ATP AND is used to drive flagella rotation.

In the phototrophic production of energy, the oxygen originates from
carbon dioxide.
water.
glucose.
hydrogen peroxide.

water

Anoxygenic photosynthetic bacteria
obtain electrons from water.
do not produce oxygen as a byproduct.
may obtain electrons from H2S.
are obligate aerobes.
do not produce oxygen as a byproduct AND may obtain electrons from H2S.

do not produce oxygen as a byproduct AND may obtain electrons from H2S.

The sugar component of RNA and DNA nucleotides are synthesized
as deoxyribose and then changed to ribose.
as ribose and then changed to deoxyribose.
separately.
using the Calvin cycle.
as deoxyribose and then changed to ribose AND using the Calvin cycle.

as ribose and then changed to deoxyribose.

The change in free energy of a reaction varies.
True
False

False

Both glycolysis and the pentose phosphate pathway oxidize glucose to pyruvate.
True
False

True

Enzymes are changed by the reaction as they raise the activation energy.
True
False

False

Competitive inhibition usually involves both substrate and inhibitor competing for binding at the allosteric site.
True
False

False

The production of ATP via the electron transport system, in either eukaryotes or prokaryotes, requires the use of a membrane.
True
False

True

The TCA cycle must "turn twice" in order to complete the oxidation of one glucose molecule.
True
False

True

The terminal electron acceptor in aerobic respiration is water, which is broken down to hydrogen and oxygen.
True
False

False

In fermentation, the only ATP produced was during glycolysis and the fermentation reactions usually result in resetting the NADH to NAD.
True
False

True

H2S and NH3 may be used by some prokaryotes as energy sources.
True
False

True

The Calvin cycle produces 6 ATP for every 6 turns of the cycle.
True
False

False

Why would a cell ferment rather than respire?
There's no oxygen present, and it cannot respire anaerobically.
It lacks the ability to respire (i.e. no electron transport chain).
Conditions (pH, oxygen concentrations, etc.) have changed to such a point that respiration is no longer possible.
All of the above are possible.
None of the above.

All of the above are possible.

Chemolithotrophs near hydrothermal vents support a variety of life forms. Why is this analogous to photosynthetic microbes supporting life forms closer to the surface of the planet?
Because all life forms need some energy source, electron source, and carbon source. Chemolithotrophs, if consumed by other microbes, could serve as all three. This is very similar to the role that photosynthetic microbes play in the top levels of the oceans/lakes.
Because chemolithotrophs will also utilize energy from sunlight to form their sugars/get their chemical energy...much like photosynthetic microbes.
Because chemolithotrophs also pull in carbon dioxide as their carbon source, just like photosynthetic microbes.
Because photosynthetic microbes utilize heat energy from the sun as an energy source. Chemolithotrophs utilize heat energy from hydrothermal vents, but it's still heat energy. This makes both microbes similar.

Because all life forms need some energy source, electron source, and carbon source. Chemolithotrophs, if consumed by other microbes, could serve as all three. This is very similar to the role that photosynthetic microbes play in the top levels of the oceans/lakes.

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