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BIOD 171 Microbio exam answers
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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
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
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
occur in living organisms in order to maintain life. True.
transport chain yields 34 ATP while both glycolysis and fermentation (or respiration) each yield only 2 ATP.
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.
A. Objective
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.
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
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. 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.