Portage Learning BIOD 171 Microbiology Exam Questions and Answers, Exams of Nursing

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[Date] 1

.

1. A virus is classified as a microbe. True. Although viruses are not living and

as such are not considered microorganisms, they can, however, be classified as microbes, a more general term that includes microorganisms and viruses.

2. True or False: The smallest biological unit of life is the molecule. False. The

smallest biological unit of life is the cell.

3. What are the 4 main types of macromolecules found in cells? Proteins,

Lipids, Nucleic acids and Polysaccharide

1. Proteins are formed from various combinations of __________ which there are

____ known forms. Amino acids, 20

2. How many amino acids are classified as being essential amino acids? 9
3. What are the two major types of nucleic acids and their roles? There are two

major types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nucleic acids are chemical molecules that carry genetic information within the cell. DNA contains a vast amount of hereditary information and is responsible for the inheritable characteristics of living organisms. RNA is

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[Date] 2 responsible for deciphering the hereditary information in DNA and using it to synthesize proteins.

1. Complete the following RNA strand and indicate how many bonds are formed

for each complementary pair: 3’ GGUCAUCG 5’ 5’ CC AGC 3’ 3’ GGUCAUCG 5’ 5’ CCAGUAGC 3’ There are 2 bonds formed between A and U, and 3 bonds between G and C.

1. The plasma membrane (select all that are true): BD

A. Only restricts movement of materials into the cell B. Is often a bilayer comprised of lipids? C. Cannot prevent essential nutrients from escaping D. Contains hydrophobic tails pointing inward

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[Date] 3

2. Carbon, Hydrogen and Oxygen atoms come together to form what primary

macromolecule? Give an example. Polysaccharides. Glucose, sucrose and cellulose are all acceptable answers. True or False: The genetic material within a prokaryotic cell is contained within a membrane enclosed region. False. Only eukaryotic cells contain its genetic material within a nucleus True or False: Prokaryotic cells can be subdivided into Bacteria and Archaea. True Describe the 4 basic bacterial morphologies. Coccus (round/spherical), bacillus (rod), vibrio (curved rod) or spirillum (spiral/corkscrew). True or False: Archaea is noted for its ability to survive under harsh conditions. True. Archaea can often be found in harsh conditions such as high salt levels, high acid conditions, high temperatures and even oxygen-poor conditions.

1. Animalia, Plantae, Fungi and Protista are all classification under what type of

organism A. Bacteria B. Eukarya C. Archaea D. Virus

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[Date] 4

2. All multicellular microorganisms classified as Animalia are autotropic.

False—they are heterotrophic.

3. Microorganisms classified as _________ obtain most of their energy by

converting light energy into chemical energy. Plantae

1. A defining characteristic of fungi is the presence of chitin in the cell walls.

Which of following also contain chitin? Select all that apply. ACD A. Mushrooms B. Bacteria C. Yeast D. Molds

2. True or False: A defining characteristic of Protista is the inability of colonies to

form tissue layers. True.

1. Cell walls are found in which of the following (select all that apply): A, B, C, E

A. Plants B. Fungi C. Bacteria

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[Date] 5 D. Mammalian cells E. Algae

2. The function of the ribosome is (select all that apply): B

A. Lipid synthesis B. Protein synthesis C. To produce energy (ATP) D. Protein modification and distribution E. Waste disposal via hydrolytic enzymes

1. True or False: Metabolism is a controlled set of biochemical reactions that

occur in living organisms in order to maintain life. True.

2. True or False: Enzymes are polysaccharides that catalyze chemical

reactions. False. Enzymes are proteins that catalyze chemical reactions.

3. What are usually metal ions known to assists enzyme during the catalysis

reaction? Cofactors are usually metal ions and assist enzyme during the catalysis reaction.

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[Date] 6

1. Define anabolism. Anabolism is the process of building up or biosynthesis

of macromolecules from small molecular units into much larger complexes.

2. In order to convert proteins into amino acids which metabolic process

would be active? Catabolism would be active as proteins are made up of amino acids. Therefore, the process described (proteins into amino acids) is the breakdown, or catabolism of protein.

1. Describe the energy transfer process relative to both ATP and ADP .ATP has

the energy (phosphate group) to donate while ADP can accept energy in the form of a phosphate group. Thus, ATP can be reduced (ATP →ADP + Pi) while ADP can be built into ATP (ADP + Pi →ATP).

2. An organism that derives its energy (generates ATP) from photons of light is

called a _________? Phototrophic microorganism. An organism that derives its energy by removing electrons from elemental sulfur would be classified as a __________? Lithotroph

4. A reactive intermediate would be present in which phosphorylation process

A. Photophosphorylation B. Substrate-level phosphorylation

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[Date] 7 C. Oxidative phosphorylation

1. The catabolism of a single molecule of glucose goes through what 3 distinct

transitions? The breakdown of glucose goes through (1) Glycolysis then (2) Fermentation or Respiration and finally through (3) the electron transport chain (ETC).

2. What is the most energetic transition in the catabolism of glucose? The

electron transport chain yields 34 ATP while both glycolysis and fermentation (or respiration) each yield only 2 ATP.

3. Identify the reactants of the following chemical equation:

Glucose + 2NAD+ → 2 NADH + 2 Pyruvate + 2 ATP The reactants are to the left of the arrow: Glucose and 2NAD+

4. The presence of what molecule ‘signals’ to the cell that glycolysis is about to

start? Glucose-6phosphate (G6P)

5. True or False: In the absence of oxygen fermentation produces 2 ATP. False.

Fermentation only reduces NADH back to NAD+

1. What is the primary byproduct of the TCA cycle? Select all that apply .CD

A. NAD+

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[Date] 8

B. FAD

C. NADH D. FADH 2

2. True or False. The reactants of the TCA cycle directly enter and fuel the

electron transport system. False. The products of the TCA cycle (reduced electron carriers) enter and drive the production of ATP via the electron transport system.

1. In the absence of glucose, which of the following can be used as alternative

energy sources? Select all that apply. A, C, D can all be used as alternative energy sources A. Lactose B. Nucleic acids. Carbohydrates D. Lipids.

2. For the catabolism of proteins and lipids, which of the following enzymes are

used? Select all that apply and D. Proteases breakdown proteins while lipases breakdown lipids.

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[Date] 9 A. Ligases B. Proteases C. Transferases D. Lipases

3. True or False. The β-oxidation pathway catabolizes the fatty acid chains of

lipids. True

1. True or False. Plants, algae and bacteria all contain chloroplasts. False.

Chloroplasts are specific to algae and plants only.

2. The process of carbon fixation begins with which of the following reactants:

select all that apply. A, C, D, and E. Carbon fixation uses the ATP/NADPH produced during light reactions to convert CO2 and H2O into useful sources of energy (carbohydrates). A. ATP B. Glyceraldehyde- 3 - phosphate C. CO 2 D. NADPH

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E. H 2 O

1. What is one of the main functions of light reactions?

Similar to the electron transport chain, one of its main functions is to generate a proton concentration gradient to generate ATP.

2. True or False: Dark reactions can occur in the presence or absence of light.

True. The term ‘dark reactions’ (also known as the Calvin Cycle) simply denotes the second stage in photosynthesis—dark reactions do not actually require darkness in order to occur.

1. How many turns (or repetitions) of the Calvin Cycle are required to generate

one molecule of glucose? Six.

2. Complete the following equation by placing the appropriate numbers where

indicated. __CO 2 + __ATP + __NADPH + __H 2 0 → __C 6 H 12 O 6 + __ADP + __NADP+ 6 CO 2 + 18 ATP + 12 NADPH + 12 H 2 0 → C 6 H 12 O 6 + 18 ADP + 12 NADP+

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1. Match the following reactions to its corresponding enzyme:
2. A + B → A-B
3. A-B → A + B
4. A-^ + B →A + B4.

Ab + C → A + Cb A- Lyases B- Transferases C- Oxioreductaces D- Hydrolases E- Ligases F- Isomerases 1E 1. A + B → A-B Ligases

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[Date] 2A 2. A-B → A + B Lyases 3C 3. A—^ + B → A + B—^ Oxioreductaces 4B 4. Ab + C → A + Cb Transferases

1. A micrometer is defined as

A. 10

• 3

B. 10 -^6 C.10-^9 D. 10-^12 B. A micrometer is one-millionth of a meter.

2. True or False: A nanometer is longer than a micrometer.

False. A nanometer is 1,000 times smaller than a micrometer.

1. Resolution and contrast are two critical factors that influence your ability to see

an object. Explain each.

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[Date] Resolution refers to the distance between two objects at which the objects still can be seen as separate. Poor or low resolution means two (or more) objects may appear as one. Contrast is the difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult. For instance, trying to identify 2 dark colored objects at night (low light = low contrast) versus the same 2 objects in the middle of a sunny afternoon (bright light against 2 dark objects = high contrast).

1. Assuming a constant (non-adjustable) light source power, identify the part of

the microscope you would adjust to limit the amount of light entering the microscope. Select all that apply. A. Objective B. Condenser C. Iris diaphragm D. Eye piece

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[Date] C. The iris controls the amount of light that passes through the sample and into the objective lens. Thus, it can be adjusted (opened or closed) to alter the amount of light.

2. What is the total magnification (relative to your eye) of a sample imaged with a

60x objective and a 10x eyepiece? Show your math. 60 x 10 = 600x magnification

1. True or False: A cell that is adherent, flat (thin) and unstained is easily identified

using bright field microscopy. False. Adherent, flat cells are almost invisible due to the limits on both resolution and contrast.

2. Which of the following could be seen clearly by the unaided eye? Select all that

apply. A. Bacteria with diameter of 24 μm B. Protozoa with diameter of 150 μm C. Virus with a diameter of 0.2 μm D. Skin cell with diameter of 1500 μm

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[Date] B and D. The unaided eye can, on average, clearly resolve objects > 100 μm

1. For each of the following questions select from the list below the single best

answer: Phase-Contrast Dark Field Fluorescence Confocal This type of microscope is best suited for visualizing GFP, RFP and YFP proteins. Fluorescence

2. This type of microscope can provide detailed images of live cells without

staining. Phase-Contrast

3. This type of microscope is used to greatly increase the contrast between

samples and background by reflecting light off of the specimen. Dark Field

4. This type of microscope is capable of capturing images in multiple focal planes,

rendering a specimen in 3D Confocal

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[Date]

1. Gram-Positive cells appear _______ in color due to a ______ peptidoglycan

layer in the cell wall. Purple; Thick

2. Gram-Negative cells appear _______ in color due to a ______

peptidoglycan layer in the cell wall. Pink; Thin

1. True or False: The distinguishing characteristic of Gram-Negative bacteria is

the presence of LPS in the outer membrane. True.

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[Date]

2. True or False: If you wish to study the motility of an organism you cannot

heat fix, but you can chemically fix the specimen. False. Both heat and chemical fixation strategies will kill the cell, making motility observations impossible.

1. You want to observe the size and shape of a cell. What is the easiest

staining technique that you could perform? Name at least one dye you would use during this process. Simple stain. You could use any of the following: methylene blue, crystal violet, safranin or fuschin.

2. You suspect a patient may have TB. Once a sample has been obtained it is

sent off to the lab for an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on the stained slide. You would expect to see red cells (TB+) on a blue background (TB negative).

3. True or False: A Giemsa stain can be used to determine the presence of

pathogenic bacteria. True. Pathogenic bacteria would appear pink while nonpathogenic bacteria would appear purple.

1. True or False: Differential media is best suited for distinguishing between

two similar species of bacteria. True. Growth media does not contain restrictive factors, while selective media is best used to encourage the growth of one microbe while simultaneously discouraging the growth of the other. Since two similar species of microbes are being studied they must be differentiated under similar but just slightly different conditions (differential media).

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[Date]

2. A researcher is asked to determine if a sample contains Neisseria

meningitides. Knowing Neisseria meningitides is slow growing and other foreign microbes may also be present in the culture, which type of media would be best suited A. Growth media B. Differential media C. Selective media D. Selective and Differential media

1. True or False: LB agar is classified as a selective, non-differential media.

False. LB agar is the most basic type of agar and like LB media supports the growth of virtually all microbes without restriction.

2. What is agar used for in microbiology? Agar is used to create a solid,

smooth surface on which microbes can grow.

1. Match the following hemolytic class with its description of activity. Alpha

hemolysis- Incomplete hemolytic activity. Beta- Complete, Gamma- No hemolytic

1. Columbia CNA agar is most closely related to which media: C

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[Date] A. Trypticase Soy Agar B. MacConkey Agar C. Blood agar D. EMB agar

2. True or False: Chocolate agar gets its brown color from cocoa to produce an

enriched media. False. Chocolate (cocoa) is never added to the media. The name is derived simply based on the color that actually comes from the presence of ‘cooked’ (lysed) red blood cells in the media.

3. A researcher is studying a strain of E. coli currently growing on a

MacConkey plate. However, the researcher can’t remember if E. coli is Gram- positive or Gram-Negative. Would a Gram stain be necessary to confirm? Why or why not? No. A Gram stain would not be necessary; as only Gram-negative microbes will grow on MacConkey agar. Thus, E. coli is a Gram-Negative microbe.

1. In an attempt to detect the presence of the pathogenic strain of E. coli

O157:H7, a researcher spread a culture onto a MacConkey agar with failed results. What type of agar should they (correctly) try next? Why? The microbe should be plated on SMAC (Sorbitol-MacConkey agar) as it is specifically formulated to detect O157:H7. Pathogenic E. coli (O157:H7) cannot ferment

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[Date] sorbitol while non-pathogenic E. coli can ferment both sorbitol and lactose. Therefore, colonies that ferment (acidic conditions; non-pathogenic) can be differentiated from non-fermenters (neutral to basic conditions; pathogenic).

1. What is the Gram status (Positive or Negative) of microbes growing on

Eosin Methylene Blue (EMB) agar plates? Gram-Negative. EMB plates specifically restrict the growth of Gram-positive bacteria.

2. Mannitol salt agar will turn what color in the presence of the pathogenic

strain Staphylococcus aureus? Yellow. Pathogenic Staph aureus will turn the agar from red to yellow.

1. What is the process of spreading a bacterial culture onto a petri dish? Plating.
2. In order to visual individual colonies of bacteria would you culture your sample

in a liquid media or on a solid (agar) media? Why? Solid (agar) media. The primary advantage is that cells are held into place. When grown in a nutrient broth, bacterial cells can multiply but are free to move around in solution. When grown on agar within a petri dish the fixed in such a way as to form colonies.

3. True or False? The visualization of colonies on a petri dish represents bacterial

cells that have often multiplied a million times over. True. To form a bacterial

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[Date] colony, the initial cell must have multiplied many times over, often greater than a million, in order for the naked eye to resolve it.

1. True or False. The purpose of a quadrant streak is to produce individual

colonies of a bacterial population. True. The purpose of the quadrant streak is to generate individual colonies such that a single (pure) bacterial sample can be isolated.

2. A dilution gradient is formed when carrying out what generalize plating

strategy? A quadrant (aka phase-dilution) streak. The resulting gradient should always contain within it the growth of individual colonies.

3. In what phase of a dilution streak would you expect to find the highest

concentration of bacteria, P2 or P4? P2 (Phase 2) would contain a higher concentration of bacteria than Phase 4 (P4). The phases rank (from highest to lowest), P1 > P2 > P3 > P4.

1. True or False. When performing a dilution streak a new (or sterilized) loop

must be used for each phase. True. Failure to do so would prevent the establishment of a dilution gradient, as the same bacterial concentration would be spread across both phase regions.

2. In order to encourage growth of a slow growing microbe what might a

researcher do during a phase dilution streak? A researcher may either (1) opt to

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[Date] perform only a 3-phase dilution streak or (2) pass the loop through the previous phase multiple times (as opposed to only once).

3. True or False. To restrict the growth of a pathogenic microbe a researcher

might decrease an incubator from 37°C to 25°C. True. Pathogenic strains of bacteria tend to grow faster than nonpathogenic strains at 37°C, so researchers may set incubators at 25°C to restrict its growth. When given an unknown bacterial sample the first step is to expand the current bacterial population. Which form of media best suites this need? Why? A. MSA agar B. LB media containing ampicillin and neomycin C. MacConkey agar D. Blood agar D. Blood agar. All other options (A, B and C) are all forms of selective media, meaning they may potentially inhibit the growth of the unknown sample. Although blood agar is considered a differential media, it is, most importantly, a non-selective media. Given the alternatives, this is the best option.

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[Date]

1. Define the concept of universal precautions. Universal precautions mean

any and all samples, whether known or unknown, are to be treated as potentially hazardous (or pathogenic) materials.

2. List at least 3 observations a researcher would be sure to note while

assessing an unknown microbial sample A lab researcher would be certain to note:1. Size and shape2. Any observable motility3. Gram status (positive or negative)4. The presence of any chemical reactions5. Changes in color localized to the organism or the surrounding media6. Capture (or draw) images of any of the characteristics described above

1. While observing an unknown sample of limited amounts, a researcher must

determine the following observations: (1) the presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would you determine first and why? You must determine motility before determining the Gram status. Motility requires a wet mount, while Gram staining requires heat fixing the sample. If one were to begin with the Gram stain the heat fixation process would kill the organism, making any observations regarding motility impossible. The correct approach would be to place the liquid culture on a glass slide and determine its motility status. Next, the same liquid culture can be heat fixed and Gram stained.

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[Date]

2. A facultative anaerobe is a microorganism capable of growth under what

conditions? A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions.

1. As Streptococcus is catalase negative would it thrive or die in the presence of

peroxides? Why? Streptococcus would not survive in the presence of peroxides—it is unable to breakdown peroxides (catalase negative). Left unchecked, peroxides would damage the cellular integrity of Strep causing lysis/cell death.

2. Streptococcus is most often streaked onto C

A. Chocolate agar B. EMB agar C. Blood agar D. Spirit Blue agar 3.True or False. The Lancefield groups are used to subdivide antigenic groups of gamma-hemolytic Streptococcus. False. The Lancefield groupings are used to subdivide beta-hemolytic Strep.

4. Greater than 90% of all human streptococcal infections belong to: C (group A)

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[Date] A. Group B B. Group D C. Group A D. Group C

5. Left untreated, strep throat can progress to ______ , which displays _____

hemolytic activity A. Strep. Pharyngitis; beta B. Strep. Septicemia; gamma C. Rheumatic fever; beta D. Strep. Pharyngitis; alpha

1. True or False. Under most circumstances, staphylococcus can be found in ~30%

of human population where it remains pathogenic. False. While staphylococcus can be found in ~30% of the human population, it remains non-symptomatic.