Microbiology Test 1

Alexander Fleming discovered the antibacterial properties of penicillin.

True

Penicillin interrupts synthesis of peptidoglycan which causes rupture of the bacterial cytoplasmic membrane

True

The idea that life comes from nonliving material is known as ___________________.

spontaneous generation

The fist cells appeared about _______ billion years ago.

3.8

Which of the following is NOT a microorganism?

Mosquito

All of the following are infectious diseases except:

diabetes

A(n) _________ only causes disease in a weakened host.

opportunistic pathogen

The Dutch merchant who made and used quality magnifying lenses to see and record microorganisms was _________.

Antonie van Leeuwenhoek

All microorganisms are best defined as organisms that ___________.

are too small to be seen with the unaided eye

Koch’s Postulates provide a useful guideline for:

relating specific microbes to certain diseases

Which of the following describes primary active transport?

ATP is used to drive transport

Louis Pasteur’s famous experiment started with him boiling a broth solution in a swan-necked flask. After boiling the broth, he tested different conditions. Which of the following was a result he observed?

breaking off the swan neck resulted in the appearance of microbes in the broth

Characteristics shared by all cells include _________.

• A membrane serving as a cell boundary

• The presence of cellular fluid (aka cytoplasm)

• The possession of genetic information

Bacterial cells are characterized by the presence of a nucleus and organelles.

False

The cytoplasmic membrane is composed of a ­­­­__________ bilayer with embedded­­­__________.

Phospholipid / proteins

A gram positive bacterial cell wall is made of a thick layer of __________ with attached _________.

peptidoglycan; teichoic acid

Bacteria that have a rod shape are called _________

bacilli

The cell wall of Gram-negative bacteria is composed of:

peptidoglycan

All of the following statements about the cytoplasmic (plasma) membrane are true EXCEPT:

it has ribosomes attached to it for synthesis of RNA

The surgeon who advocated using disinfectants on hands and in the air prior to surgery was ________.

Joseph Lister

The order of phases in a bacterial growth curve is:

lag, log, stationary, death

Bacteria cells grown in culture form cell masses known as:

colonies

The process by which bacteria divide is known as:

binary fission

Choose the true statement about growth factors

An amino acid may be an example.

Binary fission is the process whereby:

one cell spits into two equally sized cells

In the ________phase, bacteria do not divide much but increase in size, replicate DNA, and express genes to synthesize enzymes needed to digest nutrients in their environment

lag

Laura has a urinary tract infection, most likely caused by Escherichia coli. Which structure aids in the ability of E. coli to attach to the urethra, even during the full force of urination?

pili

Microbial pathogens that cause disease in humans obtain carbon from organic molecules found within the human host. Based on this information, these microbial pathogens would best be defined as:

heterotrophs

Bacterial endospores are ___.

• resistant to radiation

• non-growing

• formed upon nutrient limitation

• made by some human pathogens

Which of the following does NOT describe an essential nutrient?

A necessary substance that a microbe makes.

What distinguishes the lag phase of bacterial growth from other phases?

The number of bacteria does not increase significantly in number but they are metabolically active

You isolate a new bacterium from the environment and find that it grows best at 11°C and uses O­2 during cellular respiration. Which terms best describe this organism?

psychrophile, aerobe

The primary purpose of bacterial endospores is:

to allow certain cells to enter a dormant state.

Swimming motility is caused by the ___ of ___ in bacteria.

rotation; flagella

For microbes, growth is defined as

an increase in cell numbers

Which of the following is not a stage of the microbial growth curve?

turbidity

Choose the true statement about phototrophs.

Phototrophs use light for energy.

Solid growth media, such as an agar plate, is useful for obtaining isolated colonies of microbes.

True

Which is NOT a reason why endospore-forming bacteria pose challenges in healthcare settings?

Endospores are only produced by Gram-positive organisms.

Which of the following statements about anaerobic respiration is true?

• inorganic molecules other than O2 are used as the terminal electron acceptor

• ATP is made by oxidative phosphorylation

• fewer protons (H+) are pumped across the membrane compared to aerobic respiration

Fermentation is an anaerobic process that results in the oxidation of NADH to form NAD.

True

If a bacterial chromosome consists of 30% adenine, what percent guanine would you expect to find in the chromosome?

20%

Which of the following is an accurate representation of a double-stranded DNA sequence?

5’-ATGCCGTAG-3’

3’-TACGGCATC-5’

Glucose is not the preferred carbon source for most microbes.

False

Aerobic and anaerobic respiration yield the same amount of ATP per molecule of glucose.

False

Substrate level phosphorylation occurs during:

glycolysis and citric acid cycle

During glycolysis, a total of ___ ATP are created and ___ ATP are used for each molecule of glucose.

4, 2

Spontaneous mutations:

are the result of errors in the base pairing of nucleotides during replication.

____ are capable of coupled transcription-translation.

prokaryotes

Synthesis of a protein molecule from information encoded in RNA is called

translation

Which of these processes is most associated with a flow of electrons pumping hydrogen ions across a membrane?

Electron transfer chain

The three phases of translation include which of the following?

Initiation, Elongation, termination

Catabolism is...

• When carbohydrates, lipids, and proteins are chemically broken down

• Reactions are oxidative

• Energy is released and ATP synthesized

• Smaller biomolecules are produced

Which of the following statements about enzyme regulation is true?

Noncompetitive inhibitors bind to a site other than the active site.

RNA can function as a catalyst during peptide bond formation.

True

All information for the structure and function of an microorganism is coded in its

genes

A permanent alteration in a DNA sequence is known as a(n)

mutation

How do enzymes catalyze chemical reactions in living organisms?

Enzymes lower the activation energy needed for a reaction to occur

RNA can adopt intricate dimensional structures.

True

Influenza is an enveloped virus. Where does the envelope come from?

the cytoplasmic membrane from the host cell

Oncogenic viruses are capable of causing cancer.

True

Which of the following DOES NOT describe enveloped virus replication?

release through host cell rupture

Replication of a double-stranded RNA (dsRNA) virus:

requires the virus to bring a RNA-dependent RNA polymerase

A bacteria has a mutation present in its gene sequence for a particular protein. What downstream molecules will this effect?

mRNA and protein

Bacteriophages

may undergo a lytic cycle

Horizontal gene transfer refers to processes by which bacteria can uptake DNA from their environment or other cells.

True

Tropism is defined as:

the range of cells/tissues in a host that a virus can replicate within

A mutation arising from transcription (a mutated mRNA molecule) will affect all proteins made thereafter.

False

In general, most DNA viruses multiply in the animal host cell’s _________, while most RNA viruses multiply in the animal host cell’s ___________.

Nucleus/cytoplasm

Host range limited by _________.

Type of host cell receptors on cell membrane

Which of the following steps is NOT part of lysogenic replication?

assembly

Prions are not:

affected by radiation that would cause mutations

All viruses possess a lipid / protein outer layer known as the

viral envelope

Which of the following represents the correct order of steps in a typical virus replication cycle?

attachment —> entry —> biosynthesis —> assembly —> exit

In _____________ viral infections, there is a continous release of virions over time and a slow progression of disease.

chronic

Conjugation requires what structure to work?

Pilus

Viruses may be classified

• by the shape of their capsid

• by the presence or absence of an envelope

• by the type of nucleic acid they possess

• as single or double stranded

All viruses:

are obligate intracellular parasites

Horizontal gene transfer is often how antibiotic resistance genes are spread between bacteria.

True

Which of the following is an example of a noninfectious disease?

Alzheimer's

A bacterial infection becomes a disease when ______.

damage occurs that impairs host function

Protozoans cause many gastrointestinal diseases such as giardia in dogs.

True

Virulence is _______.

the degree to which a microbe is able to cause disease

Growth of a microorganism after entering a host is called _______.

colonization

The ability of a pathogen to enter a cell, spread, and cause disease is termed ______.

invasion

The ability to produce disease is known as a microbe's:

pathogenicity

A bacterial pathogen with a LD50 of 50 would be considered ___ virulent as a bacterial pathogen with a LD50 of 5,000 [you may assume everything else is equal].

more

Hemolysin is a type of exotoxin that helps bacteria to ______.

acquire nutrients from the host cell

An infection always manifests as disease symptoms.

False

The first primitive eukaryotic cells likely evolved from ________.

the last common ancestor

Filamentous molds grow as long, tubular filaments called hyphae. The complete network of hyphae that creates a mold colony is referred to as a(n) _______.

mycelium

Fungi can be differentiated from plants by the fact that:

fungi are chemoheterotrophs, plants are photoautotrophs

All eukaryotic microorganisms are multicellular.

False

Which of the following is true regarding DNA found in eukaryotes?

• it is complementary

• it is tightly associated with histone proteins

• it is replicated in a semi-conservative manner

• it is a double helix

Which of the following is a type of eukaryotic microbe?

alveolates

Cells walls in fungi are often made of ___.

chitin

Some eukaryotes undergo sexual reproduction in a process known as:

meiosis

Infection refers to the _______.

multiplication of a pathogen within or on host's body

A symptom:

can be observed or felt only by the patient

All of the following would be considered side effects of an antimicrobial agent EXCEPT:

prophylactic effect