Microbiology Lecture Exam #1

Protozoan motility structures include

• flagella.

• cilia and pseudopods only.

• pseudopods.

• cilia, flagella, and pseudopods.

cilia, flagella, and pseudopods.

Regarding Louis Pasteur's experiments with the S-neck flask, which of the following statements is TRUE?

• The possibility of contamination was removed

• All preexisting microorganisms were killed

• All of the answer choices are correct

• A food source was provided

All of the answer choices are correct

The first step for directly linking a microbe to a specific disease according to Koch's postulates is to

obtain a sample of blood or other body fluid from a diseased animal.

In which of the following situations would Koch's postulates be utilized?

determination of the cause of a new emerging disease by scientists studying disease transmission

The term used to describe a disease-causing microorganism is

pathogen.

Which of the following findings was essential for Edward Jenner's vaccination process?

Exposure to a milder disease form may produce immunity.

Fungal infections are studied by

mycologists.

Normal microbiota are typically found in and on all the following body locations EXCEPT the

blood.

Which of the following statements about biofilms is FALSE?

Compared to free-living bacteria, biofilms are more sensitive to antibiotics.

In the name Staphylococcus epidermidis, Staphylococcus is the

genus.

Which microscope is used to see internal structures of cells in a natural state?

phase-contrast microscope

Which microscope uses visible light?

differential interference contrast microscope

This microscope produces an image of a light cell against a dark background; internal structures are NOT visible.

darkfield microscope

A virus measures 100 nm in length. What is its length in μm?

0.1 μm

Which of the following correctly traces the path of light through the compound microscope?

light source; condenser; specimen; objective lens; ocular lens

Which microscope can be used to visualize DNA or botulinum toxin?

scanning tunneling microscope

Which microscope is most useful for visualizing a biofilm?

scanning acoustic microscope

What is the total magnification of a specimen viewed with a 10x ocular lens and a 45x objective lens?

450x

Which microscope is used to observe viruses and the internal structure of thinly sectioned cells?

transmission electron microscope

The resolution of a microscope can be improved by changing the

wavelength of light.

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.

The purpose of the ocular lens is to

magnify the image from the objective lens.

In microscopy, the term resolution

refers to the ability to distinguish fine structure and detail in a specimen.

Which of the following statements is INCORRECT regarding prokaryotic cells?

They lack a plasma membrane.

Which drawing in the figure above possesses an axial filament?

A

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

They are sensitive to penicillin.

Which of the following structures is NOT found in some prokaryotic cells?

cilium

Functions of the glycocalyx include all of the following EXCEPT

binary fission.

Each of the following statements concerning the gram-positive cell wall is true EXCEPT

it protects the cell in a hypertonic environment.

Which of the following terms best describes the cell in Figure 4.2?

lophotrichous flagella

The terms "run" and "tumble" are generally associated with

taxic movements of the cell in response to attractants or repellents.

In the figure above, which diagram of a cell wall is a gram-negative cell wall?

b

Where are phospholipids most likely found in a eukaryotic cell?

the plasma membrane, around organelles, and surrounding flagella

How do spirochetes and spirilla differ?

Spirilla have an external flagella but spirochetes have axial filaments.

Which of the following is NOT a typical characteristic of most bacterial plasma membranes?

contains cholesterol

Which of the following statements is TRUE?

Endospores allow a cell to survive environmental changes by producing a dormant period with no growth.

Which of the following pairs is mismatched?

centrosome — food storage

Which of the following compounds is NOT an enzyme?

coenzyme A

Which of the graphs in Figure 5.5 best illustrates the activity of an enzyme that is saturated with substrate?

C

A strictly fermentative bacterium produces energy

by glycolysis only.

Which of the following is NOT necessary for respiration?

oxygen

In green and purple bacteria, electrons to reduce CO2 can come from

H2S.

Assume you are growing bacteria on a lipid medium that started at pH 7. The action of bacterial lipases should cause the pH of the medium

decrease.

Which of the following has bacteriochlorophylls and uses alcohols for carbon?

photoheterotroph

Cyanobacteria are a type of

photoautotroph.

Which of the following statements are TRUE?
1-Electron carriers are located at ribosomes.
2-ATP is a common intermediate between catabolic and anabolic pathways.
3-ATP is used for the long-term storage of energy and so is often found in storage granules.
4-Anaerobic organisms are capable of generating ATP via respiration.
5-ATP can be generated by the flow of protons across protein channels.

2,4,5

Which organism is NOT correctly matched to its energy source?

photoautotroph - CO2

Refer to the figure above. In aerobic respiration, where is water formed?

D

What is the fate of pyruvic acid in an organism that uses aerobic respiration?

It is converted into acetyl CoA.

How would a competitive inhibitor interfere with a reaction involving the enzyme shown in the Figure above?

it would bind to a.

The addition of which of the following to a culture medium will neutralize acids?

buffers

Salts and sugars work to preserve foods by creating a

hypertonic environment.

Which of the following is an advantage of the standard plate count?

determines the number of viable cells

Which of the following is an advantage of the direct microscopic count?

requires no incubation time

Most bacteria reproduce by

binary fission.

In the figure above, which line best depicts an obligate anaerobe in the presence of O2?

C

The figure above shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which sections of the graph illustrate a logarithmic change in cell numbers?

b and d

Most bacteria grow best at pH

7.

Which of the following pairs of microbe classification terms and optimal growth temperatures is mismatched?

thermophile — growth at 37°C

During which growth phase will gram-positive bacteria be most susceptible to penicillin?

log phase

Which of the following is NOT a direct method to measure microbial growth?

metabolic activity

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?

facultative halophiles

In the figure above, which tube shows the expected growth pattern for a facultative anaerobe?

B

The following data show growth of two bacteria on different media. The data in the table above indicate that S. aureus is a(n)

facultative halophile.

Patients with indwelling catheters (long-term tubes inserted into body orifices for drainage, such as through the urethra and into the urinary bladder) are susceptible to infections because

biofilms develop on catheters.

In the figure above, which line best depicts a psychrotroph incubated at 0°C?

B

Parasitic worms, even meters-long tapeworms, are studied in microbiology because

diagnosis usually involves microscopic examination of patient samples.

Semmelweis advocated handwashing as a method of preventing which of the following diseases?

puerperal fever

Which of the following types of microbe was NOT observed by Leeuwenhoek?

virus

Inserting a gene from the hepatitis B virus into yeast so that the yeast produces a viral protein is an example of

genetic engineering.

What is the CORRECT order for the application of Koch's postulates?
I. Inoculate suspect agent into test subject and observe that subject develops disease of interest.
II. Isolate and culture suspect agent in the laboratory.
III. Find suspect agent is every case of disease of interest but not in healthy hosts.
IV. Recover and isolate suspect agent from test subject.

III, II, I, IV

Which of the following is an incorrect pairing?

protozoa; multicellular

The principle of disinfection to reduce HAIs (healthcare associated infections) among patients was initially introduced by

I. Semmelweis and J. Lister.

Which of the following chemical substances contributes to the unique characteristics of acid-fast bacteria?

mycolic acid

Which of the following statements concerning cellular metabolism is FALSE?

Macromolecules are converted into cell structures via catabolism.

Sulfanilamide is an antimicrobial drug that mimics the shape of an important substrate for a particular bacterial enzyme, thereby inhibiting the enzyme. This type of inhibition is known as

competitive inhibition.

An organism is found in a deep-sea vent where the temperature is very high and the mineral content very unusual. The organism is unicellular, has no apparent nucleus, and has a cell wall but no peptidoglycan. This organism would be classified as which of the following types of organisms?

archaea

Hooke and van Leeuwenhoek helped to create the basis of the cell theory by

observing and documenting cells, and using microscopes to visualize the invisible structure of living things

Which of the following types of microscopy is used to study the structure of the slimy accumulation of bacteria on an IV catheter tip?

scanning acoustic

Which of the following statements about ribosomes is FALSE?

Antibiotics that interfere with protein synthesis harm both prokaryotic and eukaryotic ribosomes.

Why is penicillin selectively toxic to bacterial cells but harmless to human cells?

Penicillin specifically weakens peptidoglycan, which is found only in bacterial cells.

When fermentation tests are used to help identify bacteria, which of the following end-products is typically detected by a color change?

Acid

Nitrobacter bacteria use carbon dioxide for their carbon source and nitrate ions as an energy source. This organism is a

chemoautotroph

Which of the following pairs is NOT correctly matched?

Oxidation; reaction in which electrons are gained

NADH molecules formed during glycolysis and in the Krebs cycle are

oxidized when electrons are passed to the electron transport chain

Which of the following prokaryotic cells contain an outer membrane?

Gram-negative bacteria only

What metric unit would be most appropriate for expressing the size of most viruses?

nanometer

Which microscope is especially useful in studying the surface structures of intact cells and viruses?

• Darkfield microscope

• Phase-contrast microscope

• Transmission electron microscope

• Scanning electron microscope

Scanning electron microscope

If cells are grown in media containing amino acids labeled with radioactive nitrogen (15N), most of the radioactivity will be found in the cells'

DNA and proteins.

Which microscope illuminates specimens with blue light and produces three-dimensional images?

Confocal microscope

The biosafety level (BSL) for most introductory microbiology laboratories is

BSL-1

Which microscope uses an ultraviolet light source?

Fluorescence microscope

A culture medium consisting of agar, peptone, and beef heart is a

complex

Which of the following contain 70S ribosomes?

prokaryotes, mitochondria, and chloroplasts

What is the function of the diaphragm on a compound microscope?

controls the amount of light entering the condenser

Lecture Essay Score: 4.5/5
Clostridium and Streptococcus are both catalase-negative. Streptococcus grows by fermentation. Why is Clostridium killed by oxygen, whereas Streptococcus is not?

Both Clostridium and Streptococcus lack catalase, which prevents them from breaking down hydrogen peroxide appropriately. Clostridium, an obligate anaerobe, finds oxygen itself toxic, which disrupts essential cellular processes and leads to cell death. Streptococcus, on the other hand, is a facultative anaerobe. Despite lacking catalase, it can survive in oxygen-rich environments by fermenting sugars for energy and can switch to aerobic respiration when oxygen is present.