Test 1 - Microbiology (Ch. 1-5)

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Chapters 1-5
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College: Second year
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Which of the following processes of making blue jeans is incorrectly matched?

cotton - Fungal hyphae


Which of the following statements about biofilms is false

compared to free living bacteria, biofilms are more sensitive to antibiotics


Regular use of antibacterial cleaning products

promotes survival of bacteria that are resistant


In the name Escherichia coli, coli is the

specific epithet


which of the following is the best definition for biotechnology

The use of living organisms to make desired products


which of the following pairs is mismatched

Immunologist - studies ecology of legionella pneumophila


Who proved that microorganisms cause disease



Who disproved the theory of spontaneous generation



Which of the following statements about viruses is false

they cannot reproduce themselves


which of the following is a scientific name

Streptococcus Pyognesis


The pH of a solution reflects the hydrogen ion concentration. A change from pH 7 to pH 8 reflects a _______________ change in hydrogen ion concentration.



Consider an atom of sodium with an atomic number of 11 and an atomic weight of 23. How many neutrons are in this atom?



Starch, dextran, glycogen, and cellulose are polymers of



which molecule is composed of a chain of amino acids



what do genes consist of

nucleic acid


which of the following pairs is mismatched?

MgSO4 -> Mg2+ + SO4 2- = Salt


which type of molecule is composed of (CH2O) units?



Identify the following reaction: NH3 + H2O

Reversible Reaction


Which of the following is the type of bond holding K+ and I- ions in KI?

Ionic Bond


When an atom's outer electron shell is only partially filled, the atom is considered:

chemically unstable


which of the following statements about protozoa is false

they have rigid cell walls


which of the following pairs is mismatched

Van Leeuwenhoek - germ theory


Who was the first one to observe microorganisms with a microscope

Van Leeuwenhoek


Drag each of the of the following statements to the appropriate bin to indicate wether it is a characteristic of bacteria, archae, fungi or viruses

-Bacteria: have cell walls that contain peptidoglycan, derive nutrition from organic or inorganic sources or conduct photosynthesis.
-Archae: found in extreme environments, not typically associated with human disease.
-Fungi: eukaryotic, can be unicellular or multicellular


One of the first set of experiments to refute spontaneous generation was done in 1688 by Francesco Redi. Which of the following statements regarding Francesco Redi’s experiments is true?

The results of his experiment demonstrated that living organisms are derived from other living organisms.


In 1861, Pasteur conducted his now-famous experiments using flasks with long necks bent into an S-shape. Imagine that you are a scientist working in Pasteur’s lab at this time. You decide to tip the flasks so that broth enters the long S-shaped neck. You then return the flask to its upright position. Predict the most likely outcome of tipping one of Pasteur’s S-necked flasks.

The broth would become contaminated with microbes because they were trapped in the neck.


S. aureus has been isolated from George’s infected wound. To satisfy Koch’s postulates, what would George’s doctor need to do with the isolated S. aureus?

Inject the S. aureus into an animal, observe whether the animal gets an infection similar to George’s, and isolate the same strain of S. aureus from the infection.


Which of the following are limitations of antibiotics?

Antibiotics may be toxic.
Treatment with antibiotics can lead to the emergence of resistant strains.
Antibiotics are not effective in treating viral infections.


Further characterization of the S. aureus isolated from George’s wound reveals that the strain is MRSA. Why is George’s doctor concerned that MRSA has been identified as the causative agent of George’s infection?

MRSA is transmissible.


For each of the following items, indicate which viewing method is most appropriate–the unaided eye, light microscopy, scanning electron microscopy, or transmission electron microscopy–by dragging it into the correct bin.

-Unaided eye: examining your cat for the presence of fleas.
- Light microscope: examining a clinical specimen, such as a sputum smear, for the presence of bacteria. Examining a blood smear for the presence of malarial bacteria.
- Scanning Electron Microscope: viewing the three-dimetional shape of a protozoan and the arrangement and distribution of cilia on its surface. Determining the three-dimensional shape and arrangement of bacterial cells.
- Transmission Electron Microscope: confirming the 9 + 2 microtubule arrangement in an eukaryotic flagellum. Viewing ribosomes (20nm) within a bacterial cell. Viewing a cross section of poliovirus (30nm). Viewing the layer of gram negative cell wall in cross section.


Chlamydia trachomatis elementary bodies measure approximately 0.25 micrometers in diameter. What is this measurement expressed in nanometers (nm)?

250 nm


A paramecium is approximately 150 micrometers in length. What is this measurement expressed in millimeters (mm)?

0.15 mm


While staining a mixed culture of Gram-positive and Gram-negative bacteria, switching the order of steps 2 and 3 would result in ______________________.

all bacteria appearing pink


Which structural feature of Gram-positive bacteria enhances their ability to retain the crystal violet dye?

a thick peptidoglycan layer


What would you anticipate seeing if you accidentally switched crystal violet and safranin while performing a Gram stain?

All bacteria would appear purple.


What would you expect to see if you forgot to perform step 2 of the Gram stain procedure?

All bacteria would appear pink.


A key feature of cellular respiration is the removal of electrons from fuel molecules (oxidation) and the ultimate acceptance of these electrons by a low-energy electron acceptor. The process involves the use of electron carriers, NAD+ and FAD, which play crucial roles in multiple steps of the metabolic pathways. The overall equation for cell respiration is shown below. Why do NAD+ and FAD NOT appear in the overall equation?

The NAD+ and FAD are initially reduced then oxidized to their original state, so they do not appear in the net equation.


Consider the glycolysis pathway.
Select all statements that correctly describe glycolysis.

-Glucose is the original electron donor.
-The 6-carbon skeleton of glucose is enzymatically split into two 3-carbon compounds.
-Glyceraldehyde 3-phosphate is oxidized, and NAD+ is reduced to NADH.
-More ATP is formed than is consumed in this process.


Examine the figure above depicting the preparatory step and the Krebs cycle, and identify statements that correctly describe these processes.
Select all statements that correctly describe the preparatory step and the Krebs cycle.

-the oxaloacetic acid that accepts the acetyl group is regenerated, enabling the cyclic nature of this process.
-The potential energy in the pyruvate is transferred to the reduced coenzymes (NADH and FADH2).
-There are five oxidation-reduction reactions depicted.
-The equivalent of one ATP is made for each turn of the Krebs cycle.
-It takes two “turns” of the Krebs cycle to process the pyruvic acid molecules resulting from the glycolysis of one glucose molecule.
-Carbons from pyruvic acid end up as CO2.


Compare and contrast three metabolic pathways by choosing whether the statement applies to aerobic respiration.
Check all that apply.

-Much or most of the ATP produced is produced by oxidative phosphorylation.
-A total of 38 ATP are produced per molecule of glucose input.
-The coenzyme NAD+ plays an important role in the pathway.
-Process involves the Krebs cycle
-Process includes glycolysis
-End products are CO2 and H2O
-Process involves electron transport and chemiosmosis


Compare and contrast three metabolic pathways by choosing whether the statement applies to anaerobic respiration.
Check all that apply.

-Much or most of the ATP produced is produced by oxidative phosphorylation.
-Between 2 and 38 ATP are produced per molecule of glucose input.
-Can generate ATP in the absence of O2.
-Process includes glycolysis
-Process involves the Krebs cycle
-The coenzyme NAD+ plays an important role in the pathway.
-Process involves electron transport and chemiosmosis


Compare and contrast three metabolic pathways by choosing whether the statement applies to fermentation.
Check all that apply.

-The coenzyme NAD+ plays an important role in the pathway.
-Can generate ATP in the absence of O2.
-A total of 2 ATP are produced per molecule of glucose input.
-Process includes glycolysis
-End products may include lactic acid or ethanol.


When bacteria are inoculated into a new sterile nutrient broth, their numbers don’t begin to increase immediately. Instead, there is a lag phase that may last for an hour or even several days. Why don’t bacterial numbers increase immediately?

The bacteria must adjust to the nutrient content in the new medium, synthesizing necessary amino acids, growth factors, and enzymes.


Select each statement that accurately describes what is happening to bacterial cultures during stationary phase.

-Harmful waste products may be accumulating.
-the cells are likely running out of nutrients.
-The number of cells that are dying is balanced by the number of new cells that are being formed.


A chemostat is continuous culture system that is designed to promote and prolong exponential growth and prevent bacteria from entering stationary phase. How might this work?

Chemostats provide a continued source of fresh nutrients and remove wastes and dead bacterial cells.


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 after inoculation?

16 million


This activity asks you to consider various methods of counting or estimating the size of bacterial populations and to select the method that will provide the most accurate data for plotting a bacterial growth curve.
Which of the following methods would be most appropriate for gathering data to plot a bacterial growth curve throughout the four phases?

Plate count


Drag each of the following terms into the appropriate box, indicating whether it applies to prokaryotic cells or eukaryotic cells.

70's ribosomes, circular chromosome, not enclosed with a nuclear envelope, peptidoglycan-containing cell wall, flagella that rotate, composed of flagellin.

80s ribosomes, mitochondria, linear chromosomes enclosed within a nuclear envelope, cellulose or chitin containing cell walls, golgi apparatus, lysosomes, endoplasmic reticulum, flagella that wave composed of reticulum


Select the structures below that are found in all bacterial cells.

nucleoid, ribosomes, cytoplasm, plasma membrane


Indicate the bacterial structures that are likely to be antigens, to which host antibodies bind, marking the invader for phagocytosis

capsule, fimbriae, cell wall, flagella


Identify antibacterial strategies that would likely be selectively toxic for bacteria.

- inhibition of fimbriae synthesis
- inhibition of peptidoglycan synthesis
- interfering with translation at 70s ribosomes


A strain of Streptococcus pneumoniae is no longer able to synthesize its capsular polysaccharide. What is a likely outcome?

It will be readily phagocytized upon entering the host


A strain of Neisseria gonorrhoeae has been genetically altered and can no longer produce fimbriae. What is a likely outcome?

It will no longer be able to secrete exotoxins.


Select the statements that accurately describe DNA replication.

-The major replication enzyme is DNA polymerase.
-Topoisomerase and DNA gyrase remove supercoiling ahead of the replication fork.
-DNA helicase separates the DNA strands, creating a replication fork.
-DNA replication provides an exact copy of DNA for daughter cells (next generation).
- DNA replication occurs prior to mitosis and prior to binary fission.
- DNA replication is semiconservative.
- DNA replication can copy plasmids, which can be transferred among bacterial cells of the same generation.


During infection, C. diphtheriae expresses a variety of genes that are used to establish infection and cause disease. One of these genes encodes for diphtheria toxin. Expression of the toxin requires the genetic information contained in DNA be converted into protein. The 1st step in this process is transcription, in which DNA is converted into mRNA. The following is a short piece of the DNA sequence for diphtheria toxin (written 5’ to 3’): TAA GCG TAG AAC TTG. Which of the following sequences represents the mRNA (written 5’ to 3’) that will be generated from this DNA sequence?



The major virulence factor produced by C. diphtheriae is diphtheria toxin. The production of diphtheria toxin during infection is controlled by a repressor, DtxR. The activity of DtxR is regulated by iron, which acts as a corepressor. During an infection, the levels of iron available in the tissues for use by C. diphtheriae are low. What effect will the decreased iron availability have on the production of diphtheria toxin

The lack of corepressor binding to DtxR will lead to a loss of repression and an increase in the production of toxin.


Diphtheria toxin kills eukaryotic cells by affecting translation. More specifically, the toxin prevents movement of tRNAs from the A site to the P site of the ribosome. Predict what the result(s) of this inhibition would be.
Select all that apply.

-New tRNAs will not be able to enter the ribosome.
-Protein synthesis will be interrupted because the peptide chain is inhibited from growing.


Enzymes are important in living organisms because they

bring together reactants or properly orient a molecule for a reaction


competitive inhibition of enzyme involves

competition with the substrate for binding at the active sight


in an ezymatic rx involving oxidation of a substrate, which of the following would be required



During glycolosys, electrons from the oxidation of glucose are transferred to



All of the following are potential end products of fermentation except

pyruvic acid


which of the following statements about substrate level phosphorylation is false?

the oxidation of intermediate metabolic compound releases energy that is used to generate ATP


which of the following is not necessary for respiration



assume you are growing bacteria on a lipid medium that started at pH7. The action of bacterial lipase's should cause the pH of the medium to



which statement are true

2- ATP is a common intermediate between catabolic and anabolic pathways.
4- Anaerobic organisms are capable of respiration
5- ATP is generated by the flow of protons across the cell membrane


what can you conclude about an enzymes activity?

a particular enzyme is very specific to the rx it catalyzes


Which of the following is NOT a distinguishing characteristic of prokaryotic cells?

They lack a plasma membrane.


By which of the following mechanisms can a cell transport a substance from a lower to a higher concentration?

Active transport


Which of the following organelles most closely resembles a prokaryotic cell?



Which of the following statements about gram-negative cell walls is false?

They are sensitive to penicillin.


Where are phospholipids most likely found in a prokaryotic cell?

Plasma membrane


Where are phospholipids most likely found in a eukaryotic cell?

Around organelles and Plasma membrane


In the gram-stain, if the decolorizing step is deleted, gram-neg cell walls will appear ___________ at the competition of the staining procedure



Resolution is great when using an electron microscope because the __________ of the electron beam is much shorter than of visible light



Which of the following types of microscopy can be used to specifically identify pathogens (such as Mycobacterium Tuberculosis) in specimens?



Which of the following types of microscopy is most useful for viewing the internal structures of unstained specimens?



which of the following is not part of the gram stain

hydrochloric acid


the purpose of a mordant in a gram stain is

to prevent the crystal violet from leaving the cells


the best use of a negative stain is

to determine cell size and to determine cell shape


what is the total magnification of a chloroplast viewed with a 10x ocular lens and 45x objective lense



Bacterial smears are fixed before staining to

kill the bacteria and affix the cells to the slide


the resolution of a microscope can be improved by changing the

wavelength of light