Chapter 5 & 6 Microbiology

A bacterial species has been determined to have a generation time of 30 minutes. If a microbiologist starts with an inoculum of 1000 cells/ml and wants to grow it to a culture of 1,000,000 cells/ml, approximately how long should the culture be incubated? A. 3.5 hours B. 5 hours C. 24 hours D. 100 hours

5 hours

Carbon dioxide is produced only as a by-product of acetyl-CoA synthesis and the Krebs cycle during cellular respiration.

True

Chemical reactions that can proceed in either a catabolic or an anabolic direction are known as _________ reactions.

amphibolic

Which of the following types of media is INCORRECTLY paired? A. defined medium: includes components for which the exact chemical composition is not known B. complex medium: contains nutrients from partial digestion of yeasts, beef, soy, or milk C. differential medium: different bacteria utilize nutrients in different ways D. selective medium: favors the growth of some microbes and inhibits the growth of others

defined medium: includes components for which the exact chemical composition is not known

Altering the environmental pH can inhibit microorganism growth due to __________. A. denaturation of enzymes B. acidification of carbohydrates C. chelation of metal ions needed for glycolysis D. hydrolysis of enzymatic substrates

denaturation of enzymes

Fermentation differs from cellular respiration by __________. A. requiring oxygen in order to proceed B. producing only CO2 and water as end products C. using organic molecules as the final electron acceptor D. producing more molecules of ATP

using organic molecules as the final electron acceptor

Oxygenic photosynthesis releases oxygen derived from __________.

water

_________ is an enzyme that converts hydrogen peroxide to water and molecular oxygen.

Catalase

Which of the following is NOT an example of metabolic regulation by a cell? A. Cells close all membrane channels if no energy sources are needed. B. Cells use allosteric sites on enzymes to control enzymatic activity. C. If two energy sources are available, cells use the more "efficient" energy source. D. Feedback inhibition prevents cells from producing products that are in abundance.

Cells close all membrane channels if no energy sources are needed.

Which of the following is NOT associated with the streak-plate method of isolation? A. Colonies will be found growing at and below the surface of the medium. B. A solid medium is used in this technique. C. The purpose is to isolate colony-forming units (CFUs) from one another. D. A sterile inoculating loop or needle is used.

Colonies will be found growing at and below the surface of the medium.

ATP is made by substrate-level phosphorylation only during glycolysis.

False

Direct methods of measuring microbial growth are more accurate than indirect methods.

False

Fermentation is more energy efficient than aerobic glucose metabolism.

False

Fermentation results in the production of carbon dioxide and water from pyruvic acid.

False

In feedback inhibition pathways, the end product of the pathway is usually an inhibitor of the last enzyme in the pathway.

False

The carrier molecules in electron transport chains are all integral membrane proteins.

False

The most commonly used isolation technique is the pour-plate method.

False

What is the major function of fermentation? A. It reduces glucose. B. It generates a proton gradient. C. It regenerates NAD+ for glycolysis. D. It produces ADP.

It regenerates NAD+ for glycolysis.

Which of the following statements concerning nitrogen is FALSE? A. Only a few types of bacteria can engage in nitrogen fixation. B. Nitrogen is rarely a growth-limiting nutrient. C. Nitrogen is essential for the production of amino acids and nucleotide bases. D. All cells can recycle nitrogen from their nitrogen-containing molecules.

Nitrogen is rarely a growth-limiting nutrient.

Which of the following statements concerning nitrogen is FALSE? A. Rhiozobium and many cyanobacteria are examples of a few bacteria that fix nitrogen. B. All cells can recycle nitrogen from their nitrogen-containing molecules. C. Nitrogen is rarely a growth-limiting nutrient. D. Nitrogen is essential for the production of amino acids and nucleotide bases.

Nitrogen is rarely a growth-limiting nutrient.

_______________ photophosphorylation is the process in which photosystem I works with photosystem II, and electrons are used to reduce NADP+ to NADPH.

Noncyclic

Which of the following statements is NOT part of the biofilm formation process? A.The cells form a multicellular prokaryotic organism with organ-like structures. B. Cells attach to a substrate and each other with an extracellular matrix. C. The matrix of the biofilm positions the cells to conserve digestive enzymes. D. Quorum sensing allows the microbes to respond to the density of nearby microbes.

The cells form a multicellular prokaryotic organism with organ-like structures.

Acidic pH breaks the hydrogen bonds that give enzymes their characteristic shapes, thereby denaturing them.

True

Bacteria that are pathogenic for humans are usually classified as mesophiles.

True

When organisms are exposed to temperatures higher than their optimum growth temperature, their proteins are permanently denatured.

True

A molecule that gains an electron from another molecule will experience __________ in its overall electrical charge. A. a reduction B. an increase and then a decrease C. no change D. an increase

a reduction

Which of following are INCORRECTLY paired? A. glycolysis: two molecules of pyruvic acid per one molecule of glucose B. electron transport chain: three molecules of ATP per molecule of NADH C. acetyl-CoA synthesis: two molecules of acetyl-CoA per one molecule of pyruvic acid D. Krebs cycle: three molecules of NADH

acetyl-CoA synthesis: two molecules of acetyl-CoA per one molecule of pyruvic acid

Which of the following groups of microbes do NOT use oxygen as their final electron acceptor but can detoxify oxygen enough to live in its presence? A. aerotolerant anaerobes B. obligate anaerobes C. microaerophiles D. facultative anaerobes

aerotolerant anaerobes

A microbe isolated from deep ocean troughs could best be characterized as a __________. A. barophilic hyperthermophile B. mesophile C. psychrophilic alkaliphile D. barophile

barophilic hyperthermophile

Most unicellular microbes reproduce by a process called ________________.

binary fission

A coenzyme __________. A. is an inorganic part of an enzyme B. functions as an inhibitor of enzyme function C. is a small accessory enzyme D. can be derived from a vitamin

can be derived from a vitamin

A candle jar would be most useful in isolating which of the following? A. fastidious microbes B. psychrophiles C. capnophiles D. biofilms

capnophiles

A machine called a(n) ____________ removes wastes and adds nutrients to a microbial culture to postpone the onset of stationary phase.

chemostat

Sulfanilamide is a drug that interferes with bacterial enzymes in which of the following ways? A. end-product inhibition B. noncompetitive inhibition and competitive inhibition C. competitive inhibition D. feedback inhibition

competitive inhibition

NAD+, FAD, and NADP+ are all examples of __________. A. cytochromes B. precursor metabolites C. electron carriers D. enzymes

electron carriers

All of the following processes are ways that a cell can use a proton gradient EXCEPT __________. A. ATP production B. active transport C. flagellar motion D. electron transport

electron transport

A culture method designed to increase small numbers of microbes to observable levels is known as a(n) ________ culture.

enrichment

Which of the following is NOT an advantage conferred on microbial cells by a biofilm? A. extension of the microbial growth phase B. protection from environmental stresses C.ability to stick to a surface D. formation of microenvironments

extension of the microbial growth phase

An organism that can tolerate or even grow in the presence of high levels of salt is a(n) ______________.

halophile

Lithotrophs are organisms that obtain electrons or hydrogen atoms from __________ molecules.

inorganic

Feedback inhibition __________. A. is always a form of competitive inhibition B. is not reversible C. is a mechanism for controlling the actions of enzymes D. requires a cofactor

is a mechanism for controlling the actions of enzymes

The activation energy of a chemical reaction __________. A. can be achieved by lowering the temperature of a reaction B. is the same for all chemical reactions C. is lower in the presence of an enzyme D. is eliminated in the presence of an enzyme plus a coenzyme

is lower in the presence of an enzyme

The activation energy of a chemical reaction __________. A. is eliminated in the presence of an enzyme plus a coenzyme B. can be achieved by lowering the temperature of a reaction C. is lowered in the presence of an enzyme D. is the same for all chemical reactions

is lowered in the presence of an enzyme

All of the following are drawbacks to the use of spectrophotometry in estimating microbial growth EXCEPT that __________. A. it will underestimate the true number of cells if they are not uniformly in suspension B. it kills the organisms as they are being counted C. it cannot be used if there are fewer than 1 million cells per milliliter D. it cannot distinguish between live and dead cells

it kills the organisms as they are being counted

Folic acid is a precursor molecule necessary for the synthesis of which of the following? A. Amino Acids B. glycerol C. cholesterol D. nucleotides

nucleotides

Which of the following does NOT affect the activity of an enzyme? A. substrate concentration B. pH C. temperature D. oxygen concentration

oxygen concentration

Which of the following could be an optimal pH for the growth of an acidophile? A. pH 3.0 B. pH 7.0 C. pH 8.5 D. pH 11.0

pH 3.0

A cell that uses an organic carbon source and obtains energy from light would be called a _____. A. photoheterotroph B. chemoheterotroph C. photoautotroph D. chemoautotroph

photoheterotroph

An organism that uses an organic carbon source and obtains energy from light would be called a __________. A. chemoheterotroph B. chemoautotroph C. photoautotroph D. photoheterotroph

photoheterotroph

All of the following are associated with the process of glycolysis EXCEPT __________. A. production of NADPH B. production of pyruvic acid C. phosphorylation of glucose D. substrate-level phosphorylation

production of NADPH

In order to store living cells, a scientist must slow down metabolism by lowering temperature. Which of the following examples is INCORRECTLY paired? A. lyophilization: freeze and remove water using an intense vacuum; ice sublimates B. refrigeration: short periods of time C. deep freezing: long term; -50°C to -95°C D. sub-zero freezing: long term; -10°C

sub-zero freezing: long term; -10°C

Biological oxidations often involve which of the following? A. the loss of a hydrogen atom B. the gain of an oxygen atom C. the gain of an electron e- D. the loss of an oxygen atom

the loss of a hydrogen atom

Bacterial cultures go through lag phase because __________. A. the metabolic rate begins to decline B. the cells die at a faster rate than they are able reproduce C. the cells die at a faster rate than they are able reproduce D. they are adjusting to their new environment by synthesizing new enzymes in order to use various nutrients

they are adjusting to their new environment by synthesizing new enzymes in order to use various nutrients

The photosynthetic membranes that are similar to mitochondrial membranes in both structure and function are called __________________.

thylakoids