Microbiology Lab Final Exam Study Guide

A broth medium has been inoculated, and microbial numbers will be counted periodically to generate a bacterial growth curve. At 2 hours after inoculation, the culture has progressed through lag phase and is now in log phase. At this point, the population size is 1 million cells. The generation time is 30 minutes. Assuming the continuation of log growth, how many cells would there be at 2 hours of growth in log phase?

16 million

Which of the following are the products of the Krebs cycle per molecule of glucose?

2 ATP, 6 NADH and 2 FADH2

Which of the following places the steps of the Gram stain in the correct order? 1-Alcohol-acetone 2-Crystal violet 3-Safranin 4-Iodine

2, 4, 1, 3

What is the total magnification of a specimen when viewing it with the 40x objective of a compound microscope?

400x

Gram-positive bacteria that have a HIGH G+C content belong to the phylum

Actinobacteria

Where would you expect to find electron transport chains in a prokaryote?

Along the plasma membrane

What type of cell is most associated with humoral immunity?

B cell

How is bacterial translation different from eukaryotic translation?

Bacteria can begin translation before transcription has terminated

A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 Which compound was the most effective against Staphylococcus?

C

Which of the complement proteins can directly bind to the surface of a bacterial cell?

C3b

Which cells of the immune systems are the main target of an HIV infection?

CD4+

The most frequent cause of recreational waterborne diarrhea caused by

Cryptosporidium

Which of the following is NOT a step in bacterial cell division?

Disappearance of nuclear envelope

Which step in carbohydrate metabolism yields the most ATP?

ETS

What virus family has DNA as its nucleic acid AND uses reverse transcriptase?

Hepadnaviridae

Which immunoglobulin class has a dimeric structure with a secretory component?

IgA

Which antibody type needs to be blocked to desensitize a person subject to "hay fever" type allergies?

IgE

What is the most abundant type of immunoglobulin in the blood?

IgG

Which proteins on the antigen-presenting cell are recognized by the helper T-cell?

MHC proteins

Which compounds provide electrons to the electron transport system?

NADH and FADH2

Which of the following pathologic protozoa is commonly known as the "brain-eating amoeba" and causes primary amoebic meningoencephalitis?

Nagleria fowleri

The arguments supporting spontaneous generation were finally disproved by

Pasteur

What is meant by substrate-level phosphorylation?

Production of ATP by transferring phosphates directly from metabolic products to ADP

What enables replicated DNA to separate during binary fission?

The chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes

Antibodies directly interact with which innate defenses?

The complement system

Why is reduction the term used to describe the gain of an electron?

The electron acceptor's net charge decreases

An immune response to poison ivy, latex gloves or certain cosmetics that cause dermatitis are examples of which type of hypersensitivity reaction?

Type IV hypersensitivity

How do pseudohyphae in yeasts differ from vegetative hyphae in filamentous fungi?

Yeasts use pseudohyphae to invade host tissue, whereas filamentous fungi use their vegetative hyphae for obtaining nutrients

PCR uses oligonucleotide primers during DNA amplification. What is a primer?

a short sequence of DNA that binds to a complementary region of the denatured DNA

Which staining technique would be used to identify microbes in the genera Mycobacterium or Nocardia?

acid-fast stain

Conjunctivitis can be caused by bacterial and viral pathogens. What microbe causes viral conjunctivitis?

adenovirus

What is being studied by the human microbiome project?

all microorganisms living in or on the human body

A dichotomous key _____________.

all of the answers are (is a rapid and reliable method for identifying bacterial unknowns, is a series of paired statements, of which only one applies to the unknown in question, and relies heavily on biochemical tests)

Antimicrobial peptides (AMP) have properties that make them especially interesting to scientists. Which of the following is NOT a property of AMPs?

all of the following are properties of AMPs (microbes don't appear to become resistant to AMP's, broad spectrum activities, and stable over a wide range of pH)

Which of the following is used in photosynthesis by both plants and cyanobacteria?

all of the stated answers are correct (water, carbon dioxide, and sunlight)

Which of the following is NOT an antimicrobial protein?

allergen

What type of hemolysis pattern is observed by inoculating sheep's blood agar with Streptococcus pneumoniae?

alpha hemolysis

A foreign substance that elicits an immune response is called

an antigen

Which of the following is NOT a domain in the three-domain system?

animalia

What would happen the FIRST time an Rh- individual is carrying an Rh+ fetus?

antibodies to Rh factor would develop in the mother

What is the major cell wall difference when comparing archaea to bacteria?

archaea lack peptidoglycan in their cell walls

According to the endosymbiotic theory of plastid (including chloroplasts) and mitochondrial evolution, chloroplasts and mitochondria were once free-living

bacteria

The main method of identifying unknown bacteria is ___________.

biochemical tests

Viruses are not considered living organisms because they

cannot reproduce by themselves

Which of the following characteristics would NOT be used to aid in classifying a newly discovered bacterial species?

cell size

What molecule is used to capture light energy in the process of photosynthesis?

chlorophyll

A certain species of bacteria grows the best on 5% peptone, 5% beef heart extract, and 8% yeast extract. From this description, identify this general type of growth media.

complex

What is the function of the MAC complex is to

create holes in the membrane of a microbe which will result in cytolysis

How do perforins function to destroy pathogens?

creates channels in the membrane of the target cells

The end effect of untreated systemic anaphylaxis is

death

Which bacterial growth phase is occurring when the cell population is decreasing at a logarithmic rate?

death phase

Which of the following is NOT a phase of phagocytosis of a microbe?

degranulation of phagocyte upon contact with microbe

An example of a helical virus is

ebola

Assume you stain Bacillus by applying malachite green with heat and then counterstaining with safranin. Through the microscope, the green structures are

endospores

An organism's inheritable genetic traits that you may or may not physically observe is its

genotype

Attachment of HIV to the target cell depends on

gp120 combining with the CD4+ receptor

The "H" in the H1N1 virus stands for

hemagglutinin

Worldwide, the primary method of transmission of HIV is

heterosexual intercourse

There are some unconventional treatments for Inflammatory Bowel Diseases (IBD) such as fecal transplants. What is another unconventional treatment tried for IBD

infecting a person with pig whipworm

Antigen processing and presentation

is a way for a cell to give information about its activities

An individual who has a congenital immunodeficiency

is born with a defective immune system

What was the reason that Pasteur used a flask with an S-shaped neck to prove the theory of biogenesis?

it provided the physical conditions for trapping airborne contaminants and preventing microorganisms from entering the flask

Pediculus humanus capitis, the etiological agent of pediculosis, is cause by a parasitic infestation. Which type of parasite is Pediculus humanus capitis?

louse

Species belonging to the protozoan phylum Parabasalid, such as Trichamonas vaginalis, lack which cellular organelle?

mitochondria

Which of the following can be used as a final electron acceptor for aerobic respiration?

molecular oxygen

What does it mean when scientists state that there is a "degeneracy in the genetic code"?

more than 1 codon codes for a specific amino acid

What group of high G+C gram positive bacteria makes most of the commercially important antibiotics?

not Actinomyces so maybe Streptomyces

Why could the treatment for a fungal infection result in side effects to a patient's cells?

not Fungal cells and human host cells are eukaryotic, so both have cell walls made of cellulose that could be affected. so maybe Fungal cells and human cells are eukaryotic, so both reproduce via budding and that process could be affected

A nurse practitioner is reviewing a microscope slide of a skin scraping from a 12 year old child who exhibits dry, scaly and itchy patches on her arm. The slide shows branched, intertwined nucleated hyphae. Which organism would the most likely cause of this skin condition?

not a prokaryotic filamentous algae so maybe a eukaryotic fungi

An isolate of Streptococcus pyogenes was streaked on a sheep's blood agar and incubated at 37oC overnight. The next morning you observe the plate depicted by the above image. What type of hemolysis reaction does S. pyogenes exhibit?

not delta-hemolysis so maybe beta-hemolysis

Which of the following chemicals are fairly effective against endospores?

not ethanol so maybe bisphenols

Which of the following molecules is NOT made from the fermentation of pyruvic acid?

not ethanol so maybe carbonic acid

Research of gastrointestinal microbiota stems from the need to better understand the causes of several gastrointestinal diseases. Which of the following terms describes the cause of inflammatory bowel diseases (IBD)?

not immunodeficiency disease so maybe autoimmune disease

The purpose of a mordant in the Gram stain is to

not make the flagella visible so maybe prevent the crystal violet from leaving the cells

Which is NOT a phase of HIV infection

not phase 1- asymptomatic status or chronic lymphadenopathy phase 4- death

You are performing a Gram stain on gram-negative bacteria and you stop after the washing with alcohol (or acetone alcohol). What is the appearance of the bacteria at this point?

not purple so maybe red/pink

Which of the following chemical agents act by enzyme inhibition, protein denaturation, and disruption of plasma membranes.

not supercritical fluids so maybe quats

Identify the bacterial shape and arrangement labeled "D"

not tetrad bacilli so maybe sarcinae of bacilli

Why may chewing gum with xylitol reduce the numbers of dental carries, especially in children?

not the fermentation of xylitol produces alcohol, so dental carries cannot form or the fermentation of xylitol increasing the pH in the mouth, neutralizing acids produced by by cavity-causing bacteria so maybe xylitol coats teeth surfaces to repel the acids produced by cavity-causing bacteria

Determine the activity of Oxicillin on Escherichia coli.

not there is not enough information to determine the activity of the antibiotic or the bacterium is susceptible to Oxicillin so maybe the bacterium exhibits an intermediate reaction to Oxicillin

What is the result of opsonization?

phagocytosis of the target

What cellular macromolecules make up the complement pathway?

proteins

A reaction that involves the transfer of electrons from one molecule to another is referred to as

redox reaction

HIV can evade the host's immune defenses by undergoing rapid antigenic changes. How do these antigenic changes occur?

reverse transcriptase has no proofreading activity, so mutations are introduced on a basis daily

Antigens that cause immune complex reactions are

soluble

A student is looking at a bacterial specimen using the oil immersion lens, but has forgotten to put immersion oil on the slide. The specimen will appear

somewhat fuzzy and have poor resolution

Identify the part of the microscope labeled "E".

stage

How does the ribosome know if the entering charged tRNA is correct?

the anticodon on the tRNA base pairs to the codon on the mRNA

Why doesn't a bacterial colony grow until it fills the confines of the petri dish?

the bacteria with eventually deplete the nutrients in the media, resulting in substantially slower growth rates and eventually death.

Which of the following is NOT true concerning Acid-fast staining of microbes?

the mordant is methylene blue

What would occur if you forgot to add dNTPs to your PCR sample?

the target sequence will not be amplified

Which of the following statements is NOT correct about the unknown bacterial sample?

the unknown belongs to the genus Citrobacter

A recessive trait is only observed if

there are 2 copies of the recessive gene

What is the importance of Koch's postulates?

they provide experimental steps for future scientists to directly relate a specific microbe to a specific disease

What surface antigens are found of the cell membranes of type O blood?

type O blood doesn't have surface ABO antigens

If you were setting up an experiment to disprove spontaneous generation in a liquid medium, which of the following would be essential to the experiment?

using a sterile liquid and eliminating exposure to microorganisms

The significance of Jenner's work with cowpox lead to the development of

vaccines

What molecule does oxygen get reduced to at the end of the electron transport chain?

water

Why are bacterial capsules medically important (ie: what information does it provide to the physician)?

when present, it contributes to the bacteria's virulence by evading phagocytosis

What could happen if you talk, cough or sneeze while preparing a slide.

you could risk contaminating your sample