MCB Exam 3

Enzymes that break down proteins into individual amino acids are called:

reductases

lipases

dehydrogenases

proteases

amylases

proteases

The biochemical reaction, phosphoenolpyruvate (PEP) + ADP → Pyruvate + ATP, is an example of which of these?

Oxidative phosphorylation.

An aldolase catalyzed reaction.

Substrate-level phosphorylation.

An electron transport reaction.

An oxidation/reduction reaction.

Substrate-level phosphorylation.

When you add salt to meat for preservation you are:

decreasing the water activity of the meat.

increasing the pH of the meat.

decreasing the pH of the meat.

increasing the water activity of the meat.

decreasing the water activity of the meat.

Which of of these is an INTRINSIC factor that affects food spoilage?

nutrient content

atmosphere used for packaging

storage humidity

storage temperature

nutrient content

Which one of these bacterial groups are essential for cheese production:

Staphylococcus aureus

methylotrophs

lactic acid bacteria

methanogens

lactic acid bacteria

The fuel gas __________ is frequently recovered from anaerobic digesters at a waste treatment plant.

nitrogen

carbon dioxide

argon

methane

methane

Lyophilization is

the acidification of food for long term storage.

a type of canning technique.

freeze-drying of food.

salting of food for storage.

freeze-drying of food.

Vinegar production occurs through the oxidation of ethanol by:

lactic acid bacteria.

sulfate-reducing bacteria.

acetic acid bacteria.

various molds.

acetic acid bacteria.

Which element is a threat to the Everglades as its increase through agricultural run-offs is changing the flora and fauna of the ecosystem?

Methane

Phosphorous

Mercury

Iron

Phosphorous

Ozonation is a wastewater treatment used to:

remove organic pollutants.

remove phosphorus from wastewater.

disinfect wastewater.

reduce nitrogen levels in the water.

disinfect wastewater.

Which one of these is NOT a primary goal of wastewater treatment:

reduction in levels of inorganic nutrients

reduction in organic carbon levels

removal or inactivation of harmful microbes

eutrophication of the effluent

eutrophication of the effluent

Vacuum packaging inhibits the growth of microbes that:

rely on fermentation for energy metabolism.

rely on aerobic respiration for growth.

are aerotolerant anaerobes.

are obligate anaerobes.

rely on aerobic respiration for growth.

Which one of the following is an extrinsic factor that affects that rate of food spoilage?

The skin on a fruit

The storage temperature

The water content of the food

The pH of the food

The storage temperature

The top five annual food-borne diseases in the US include:

methanogens

lactic acid bacteria

Pelagibacter ubique

Salmonella

Salmonella

Which one of the following foods would have the highest water activity?

Rice

Dried Beans

Apple

Almonds

Apple

The most common food preservation method used in US households is:

freeze-drying.

curing meat.

refrigeration.

canning.

refrigeration

The hurdle concept of food preservation relies on the idea that

food freshness can only be guaranteed if low water activity is used

the application of a single hurdle prevents complete inhibition of microbial growth

all applied hurdles work synergistically to prevent microbial growth

multiple hurdles increase the need for food processing to ensure food freshness

all applied hurdles work synergistically to prevent microbial growth

Which of these is TRUE for a chemoorganoheterotroph?

Uses inorganic carbon as an energy source and a carbon source.

Uses organic carbon as an electron source and inorganic carbon as a carbon source.

Uses inorganic carbon as an energy source and organic carbon as a carbon source.

Uses organic carbon as an electron source and a carbon source.

Uses inorganic carbon as an electron source and organic carbon as a carbon source.

Uses organic carbon as an electron source and a carbon source.

Which of these is TRUE for a chemolithoautotroph? It uses:

inorganic molecules as energy sources and organic carbon as a carbon source.

organic molecules as electron sources and inorganic carbon as a carbon source.

inorganic molecules as energy sources and inorganic carbon as a carbon source.

organic molecules as energy sources and organic carbon as a carbon source.

inorganic molecules as electron sources and organic carbon as a carbon source.

inorganic molecules as energy sources and inorganic carbon as a carbon source.

Where is the reaction center of photosystems located?

Within a biological membrane.

In the cytoplasm.

Within the cell wall.

Either in the cytoplasm or within a membrane.

In the periplasmic space.

Within a biological membrane.

Lactic acid is a common fermentation product. It is produced when ___________ is reduced by electrons received from NADH.

pyruvate

ethanol

acetyl-CoA

3-phosphoglyceraldehyde

glucose

pyruvate

Which amino acids are the primary nitrogen donors for biosynthetic reactions in the cell?

glycine and serine

serine and glutamate

glutamine and serine

glutamine and glutamate

glycine and glutamate

glutamine and glutamate

What is denitrification?

The reduction of dinitrogen to nitrate.

The assimilation of nitrate by the cell.

The assimilation of ammonia by the cell.

The production of nitrate from ammonia.

The reduction of nitrate to dinitrogen.

The reduction of nitrate to dinitrogen.

The standard reduction potential (E0') for ferredoxin (Fdox/Fdred) is (-0.43 V). Based on this, which of these would you expect to be true?

Reduced ferredoxin to be a good electron donor.

Oxidized ferredoxin to be a good electron acceptor.

Oxidized ferredoxin to be a good electron donor.

Reduced ferredoxin to be a good electron acceptor.

Cannot be determined without knowledge of the ΔG0'.

Reduced ferredoxin to be a good electron donor.

The standard reduction potential (E0') for ferredoxin (Fdox/Fdred) is (-0.43 V). Based on this, which of these would you expect to be true?

Reduced ferredoxin to be a good electron donor.

Oxidized ferredoxin to be a good electron acceptor.

Oxidized ferredoxin to be a good electron donor.

Reduced ferredoxin to be a good electron acceptor.

Cannot be determined without knowledge of the ΔG0'.

Reduced ferredoxin to be a good electron donor.

The most common lipids in the cell are synthesized from ___________ and ____________.

fatty acids and hopanoids

fatty acids and glycerol

fatty acids and sterol

hopanoids and sterols

glycerol and hopanoids

fatty acids and glycerol

Which of the following would NOT be appropriate as a terminal electron acceptor during anaerobic respiration?

sulfate (SO42-)

sulfur (S0)

nitrate (NO3-)

hydrogen sulfide (H2S)

ferric iron (Fe3+)

hydrogen sulfide (H2S)

What is the term for the primary pathway for fatty acid oxidation?

Parnas pathway

Calvin cycle

β-oxidation pathway

reductive TCA pathway

pentose phosphate pathway

β-oxidation pathway

Some anoxygenic photosynthetic bacteria are able to use _______ as an electron source.

Fe3+

nitrate

H2O

H2S

CO2

H2S

When does feedback inhibition of an enzyme occur?

If a noncompetitive inhibitor binds to the active site of the enzyme.

If an end product of the pathway binds to the allosteric site of the enzyme.

If the coenzyme fails to bind to the active site of the enzyme

If an end product of the pathway binds to the active site of the enzyme.

If a competitive inhibitor binds to the active site of the enzyme.

If an end product of the pathway binds to the allosteric site of the enzyme.

How do enzymes increase the rate of a biochemical reaction?

By lowering the activation energy.

By lowering the reduction potential.

By increasing the activation energy.

By increasing the standard free energy.

By lowering the ΔG0'.

By lowering the activation energy.

Which of these technologies employs heavy isotopes of nitrogen and carbon to enrich for DNA samples from actively growing organisms?

Metagenomic sequencing

DGGE

SSU rRNA sequencing

RNA-SIP

FISH

RNA-SIP

All of the following but one are xenobiotics that frequently contaminate our terrestrial environments. Which one does NOT represent a xenobiotic?

trichloroethylene

polycyclic aromatics

nitroaromatics

lignin

polychlorinated biphenyls

lignin

Which elements necessary for microbial life are often limiting in the ocean?

magnesium and calcium

nitrogen and phosphorous

sodium and calcium

magnesium and chloride

potassium and magnesium

nitrogen and phosphorous

Which of these summarizes the overall process of nitrogen fixation?

NO3- → biomass

ammonia → N2

NO3- →N2

N2 → ammonia → biomass

ammonia → NO3-

N2 → ammonia → biomass

What is the oxidation state of carbon in glucose (C6H12O6)?

-2

0

+2

+4

-4

0

Select the correct choice for the abundances of elements found in cells, from highest to lowest:

carbon, nitrogen, oxygen, sulfur

carbon, oxygen, nitrogen, sulfur

sulfur, phosphorus, nitrogen, sodium

carbon, sulfur, nitrogen, phosphorous

carbon, potassium, phosphorous

carbon, oxygen, nitrogen, sulfur

phosphorus in middle of nitrogen and sulfur

CONPS

Phototrophic oxidation of hydrogen sulfide in Winogradsky columns is done by:

Purple sulfur and non-sulfur bacteria,

Sulfate reducing bacteria

Celluloytic bacteria

Cyanobacteria

Purple sulfur and non-sulfur bacteria,

Which of these represents MOST of the ocean's biomass?

microbes

fish and sea mammals

sea mammals

marine plants

fish

microbes

Which of these summarizes the overall reaction for nitrification?

NO3- → NO2-

NO3- →N2

ammonia → NO3-

NO3- → ammonia → biomass

NO2- → NO3-

ammonia → NO3-

Aquatic sulfur is primarily:

Present as sulfate

Present as elemental sulfur

Present as H2S

Present as dimethylsulfoniopropionate

Present as the amino acid cysteine

Present as sulfate

Which industrial process is used for the production of ammonia?

Anderson-Plamann

Haber-Bosch

Mattox

Shine-Dalgarno

Havel - Brill

Haber-Bosch

What is the oxidation state of nitrogen in nitrogen gas (N2)?

-1

+3

0

+1

-3

0

The electron donor for methanotrophs is:

acetate

methane

carbon dioxide

oxygen

methane

Elemental movement between reservoirs is called:

sink

source

reduction

oxidation

flux

flux

Herbivores mostly require microorganisms to help them with the digestion of this compound.

starch

glycogen

cellulose

proteins

cellulose

The majority of Archaea found in the human intestinal tract are _____ .

a) sulfate-reducing bacteria

b) halobacteria

c) sulfide oxidizing bacteria

d) methanogens

e) fermenters

methanogens

The bacterial group that is responsible for root nodule formation in legumes is:

Rhodobacter

Rhizobia

Roseobacter

Rhizospheres

Rhizobia

When the diet of a ruminant is drastically changed from grass to a starch rich diet, the ruminant may become very ill or die because:

the starch is broken down very slowly and the rumen becomes clogged.

the microbes in the rumen cannot break down starch.

they lack a source of protein.

of the production of large amounts of acid, resulting in acidosis.

of the production of large amounts of acid, resulting in acidosis.

These genes are important for root nodule formation:

Group of answer choices

nar

nir

nif

nod

nod

An example of a rumen fermenter is the:

sheep

human

horse

rabbit

sheep

Camels have a:

cecal fermentation

colonic fermentation

rumen fermentation

stomach fermentation

rumen fermentation

What is the electron donor for bacterial symbionts of tubeworms at hydrothermal vents?

H2S

oxygen

carbon dioxide

ferric iron (Fe3+)

H2S

Lichens contain:

root nodules

chemolithoautotrophs

a heterotrophic partner and at least one fungal phototrophic partner

at least one fungal heterotrophic partner and at least one phototrophic partner

at least one fungal heterotrophic partner and at least one phototrophic partner

Many of the rumen bacteria specialize in the breakdown of these macromolecules:

proteins

peptidoglycans

cellulose polymers

nucleic acids

cellulose polymers

What is an endophyte?

A parasite of an animal.

A parasite of a plant.

A member of the plant root rhizosphere.

A symbiont that lives inside plant cells.

A symbiont that lives inside plant cells.

Which of these is characteristic of the enzyme nitrogenase?

It converts dinitrogen to nitrate.

It is found in both prokaryotes and eukaryotes.

It is irreversibly inactivated by oxygen.

It is found in all plant symbionts.

It is irreversibly inactivated by oxygen.

Which of these contains zooxanthellae as photosynthetic symbionts?

lichen

tubeworms

corals

termites

corals

What are Zooxanthellae?

Heterotrophic symbionts of corals

Symbionts of ruminants

Photosynthetic symbionts of corals

Symbionts of tubeworms at hydrothermal vents

Photosynthetic symbionts of corals

What is the human microbiome composed of?

Only microbes that contribute to the health of humans.

All microbes that live on or within the human body.

Only microbes that live on human skin.

Only microbes that live in the intestinal tract of humans.

All microbes that live on or within the human body.

Cyanobacteria carry out oxygenic photosynthesis producing oxygen as a byproduct from the oxidation of water, which serves as the electron donor for the light-dependent reactions. How would cyanobacteria be classified?

photoorganoautotroph

photolithoheterotroph

photolithoautotroph

chemoorganoautotroph

chemoorganoheterotroph

photolithoautotroph

What are the NET products of the Embden-Meyerhof pathway, when one molecule of glucose is oxidized?

Two CO2, two pyruvate, two ATP.

Two CO2, two pyruvate, four ATP, and four electrons.

Two CO2, four pyruvate, two ATP, and four lactate

Two pyruvate, four ATP, and four acetate.

Two pyruvate, two ATP, and two NADH.

Two pyruvate, two ATP, and two NADH

Nitrification is

the conversion of nitrogen gas into nitrate

a fermentation reaction

a two-step process to oxidize ammonium into nitrate

a two-step process to oxidize nitrate into ammonium

Hydrogen is being reduced in the reaction.

a two-step process to oxidize ammonium into nitrate

Nitrogen fixation is the reduction of _______ to ammonia for cell use.

nitrite

dinitrogen gas

nitrate

nitric oxide

hydroxylamine

dinitrogen gas

How many ATP molecules is/are required to "fix" a molecule of nitrogen?

two

eight

four

one

sixteen

sixteen

A potential terminal electron acceptor for methylotrophs is:

acetate

oxygen

carbon dioxide

methane

oxygen

What possible sources of energy may be used by microbes living in hydrothermal vents?

Methane Sulfide

Most of the organic mass in soil made by decomposition of

plants

A potential terminal electron acceptor for methylytrophs

oxygen

A potential electron acceptor for methanogens is

CO2

What is bioaugmentation

addition of specific microbes to degrade a pollutant

Methanotrophs, in contrast to non-methanotrophic methylotrophs, contain this enzyme.

methane monooxygenase

FISH is a florescent microscopic used to differentiate microbes using this material

DNA probes

The difference between a mwethanotroph and a methylotrpoh

a methylotroph can oxidize any methane group while mwethanotroph oxides only methane

In terrestrial environments, where is the greatest microbial diversity found?

soil

Oxidation state of nitrogen in NO3-

+5

Atmospheric sulfur is primarily:

Present as H2S