Download BIOD 171 Microbio exam answers and more Exams Nursing in PDF only on Docsity!
BIOD 171 Microbio exam answers
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 of which there are known forms. Amino acids, 20 2. How many amino acids are classified as being essential amino acids? 9
- 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 responsible for deciphering the hereditary information in DNA and using it to synthesize proteins.
- 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
BIOD 171 Microbio exam answers
B. Is often a bilayer comprised of lipids C. Cannot prevent essential nutrients from escaping D. Contains hydrophobic tails pointing inward
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 of 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? B A. Bacteria B. Eukarya C. Archaea D. Virus 2. All multicellular microorganisms classified as Animalia are autotropic. False—they are heterotropic. 3. Microorganisms classified as obtain most of their energy by converting light
BIOD 171 Microbio exam answers
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 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
BIOD 171 Microbio exam answers
occur in living organisms in order to maintain life. True.
BIOD 171 Microbio exam answers
transport chain yields 34 ATP while both glycolysis and fermentation (or respiration) each yield only 2 ATP.
BIOD 171 Microbio exam answers
- 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-6- phosphate (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+ 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 C. Carbohydrates D. Lipids.
BIOD 171 Microbio exam answers
True. The term ‘dark reactions’ (also known as the Calvin Cycle) simply denotes the second
BIOD 171 Microbio exam answers
stage in photosynthesis—dark reactions do not actually require darkness in order to occur.
- How many turns (or repititions) of the Calvin Cycle are required to generate one molecule of glucose? Six.
- Complete the following equation by placing the appropriate numbers where indicated. CO 2 + ATP + NADPH + H 20 → C 6 H 12 O 6 + ADP + NADP+ 6 CO 2 + 18 ATP + 12 NADPH + 12 H 20 → C 6 H 12 O 6 + 18 ADP + 12 NADP+
- Match the following reactions to its corresponding enzyme:
- A + B → A-B
- A-B → A + B
- A-^ + B →A + B-
- Ab + C → A + Cb A- Lyases B- Transferases C- Oxioreductaces D- Hydrolases E- Ligases F- Isomerases 1E 1. A + B → A-B Ligases 2A 2. A-B → A + B Lyases
BIOD 171 Microbio exam answers
A. Objective
BIOD 171 Microbio exam answers
B. Condenser C. Iris diaphragm D. Eye piece 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.
- 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
- 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.
- 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 B and D. The unaided eye can, on average, clearly resolve objects > 100 μm
- For each of the following questions select from the list below the single best answer: Phase-Contrast Dark Field
BIOD 171 Microbio exam answers
- True or False: The distinguishing characteristic of Gram-Negative bacteria is the presence of LPS
BIOD 171 Microbio exam answers
in the outer membrane. True.
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 non-pathogenic 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). 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: C A. Growth media B. Differential media C. Selective media
BIOD 171 Microbio exam answers
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.
- 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 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.
- 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 sorbitol while non-pathogenic E. coli can ferment both soribitol and lactose. Therefore, colonies that ferment (acidic conditions; non-pathogenic) can be differentiated from non-fermenters (neutral to basic conditions; pathogenic).
BIOD 171 Microbio exam answers
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 as 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 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.
