2024 C Microbe Mission Test PDF

1 Multiple Choice Each multiple choice question is worth 1 point. 1) You have discovered a new strain of bacteria and are trying to understand its morphology and structure. The first thing you want to do is to produce an image of the general structure of the new bacteria and obtain...

1 Multiple Choice Each multiple choice question is worth 1 point. 1) You have discovered a new strain of bacteria and are trying to understand its morphology and structure. The first thing you want to do is to produce an image of the general structure of the new bacteria and obtain an idea of its surface roughness for future applications. What form of microscopy would you use? a) TEM b) SEM c) Fluorescence microscopy d) Phase contrast microscopy 2) In order to identify the amount of a protein in a cell, you stain the cells with an identifying dye. Then, you are tasked to look under a microscope and quantify the amount of the protein present in the cells. What form of microscopy would be the most beneficial to use for this process? a) Fluorescence microscopy b) Phase contrast microscopy c) Bright field microscopy d) Dark field microscopy 3) Which cell type is able to have phospholipid monolayers? a) Bacteria b) Archaea c) Eukarya 4) What lipid tail type do archaea have? a) Fatty acid b) Isoprene c) Glucose d) Pseudomurein 2 5) You are conducting an experiment to look at the single stranded DNA of a eukaryotic cell during replication. In order to do this, you introduce Aphidicolin, which inhibits DNA polymerase. However, when you test the DNA composition, you find that there are no single-strands of DNA. Assuming SSBs are performing properly, which protein involved in DNA replication is most likely inhibited? a) DnaA b) Primase c) DNA ligase d) DNA helicase 6) What protein is needed to connect the Okazaki fragments? a) SSB b) DNA ligase c) DnaA d) DNA polymerase 7) Cyanobacteria are placed in a controlled environment where the amount of N2 in the air is significantly reduced. Which process will be most affected by this? a) Nitrogen fixation b) Nitrogenase c) Nitrification d) Denitrification 8) In what condition does the trp operon become active? a) When tryptophan levels are high b) When tryptophan levels are low c) In the presence of glucose d) In the absence of lactose 3 Listed below are 4 sterilization techniques. In questions (9-12), there are examples of items that require sterilization. Choose the best method for each scenario. Each method can only be used once. A) Autoclaving (heat sterilization) B) Chemical sterilization C) Ultraviolet Radiation D) Filtration 9) Cleaning surfaces : _____ 10) Sterilizing culture media : ____ 11) Air purification : ____ 12) Laboratory glassware : ____ 13) Halobacterium salinarum is an archaeon that is a type of extremophile. This archaeon cannot survive in freshwater ecosystems. Based on this information, which of the following types of extremophile is Halobacterium salinarum? a) Thermophile b) Cryophile c) Halophile d) Alkaliphile 14) Horizontal gene transfer is a mechanism by which organisms transfer genetic information to each other that are not related by parent/offspring. Lysogenic viruses facilitate horizontal gene transfer in a process known as a) Conjugation b) Transformation c) Transduction d) Viral gene transfer 15) Polymerase Chain Reaction or PCR is a technique that is utilized in comparison of nucleotide sequences. Assume we run a PCR experiment. However instead of using the Taq polymerase, instead we use DNA polymerase III found in humans. What would be the following outcome of the PCR? a) The PCR runs as normal as produces copies of the targeted sequence b) The PCR only replicates human DNA strands and not other species c) The PCR does not produce any sequences d) The PCR produces copies of the incorrect sequences 4  16) 16S amplicon sequencing is a form of sequencing that targets hypervariable regions of the 16S gene. Which of the following would it be most necessary to use 16S amplicon sequencing to differentiate the organisms? a) Escherichia coli vs. Salmonella enterica b) Streptococcus pneumoniae vs. Streptococcus mitis c) Lactobacillus rhamnosus vs. Lactobacillus casei d) Pseudomonas aeruginosa vs. Acinetobacter baumannii 17) Match each of the following community interactions to its correct definition (4 points) a. Mutualism i. Two or more species benefit from interaction b. Commensalism ii. One organism benefits at the expense of the other c. Predation iii. One organisms benefits while other is neither benefited or harmed d. Parasitism iv. One organism kills and eats the other organism 18) Which of the following bacteria most closely relates mitochondrial structure? a) Escherichia coli b) Streptococcus pneumoniae c) Rickettsia prowazekii d) Staphylococcus aureus 19) Which of the following are the inputs to oxygenic photosynthesis? a) Carbon dioxide and water b) Glucose and oxygen c) Nitrogen and hydrogen d) Sulfur and phosphate 20) Where does the calvin cycle take place? a) Chloroplasts b) Thylakoid Membranes c) Stroma d) Chlorophyll Molecules 21) Which of the following are found on fungal cell walls? Select all that apply. a) Ergosterol b) Beta 1,3 synthase c) Beta 1,6 glucan d) Mannoproteins 5 22) Which of the following correctly matches the part of a fluorescent microscope to its function? a) Dichroic mirror: absorbs light with specific wavelengths b) Excitation filter: produces fluorescent dyes that create the fluorescent image c) Emission filter: allows only emitted light from a specimen to pass d) All of the above 23) You have recently discovered a new compound with antibiotic properties, which you name Ezrium. After applying Ezrium to a sample of bacteria, you notice the presence of breakages within the cells’ chromosomal DNA, and an increased expression of proteins involved in the bacterial SOS response. Based on this observation, which antibiotic class would Ezrium most likely belong to? a) Cephalosporins b) Fluoroquinolones c) Penicillins d) Tetracyclines 24) Which of the following statements pertaining to archaeal cell structure are false? Select all that apply. a) Hami are proteinaceous filaments that allow archaeal cells to adhere to different surfaces b) Clockwise rotation of archaeal flagellum pushes the cell backward, while counterclockwise rotation moves the cell forward c) Pseudomurein, a component of archaeal cell walls, contains the sugar N-acetyltalosaminuronic acid and B-1,4 glycosidic bonds d) Side chains of the phospholipids in archaeal cell membranes are made up of isoprene units 25) The image below depicts a bacterial growth curve. Which answer choice correctly matches the letters to their corresponding phase? Refer to image 1 on the image sheet. a) A - Lag; B - Log; C - Stationary; D - Death b) A - Log; B - Lag; C - Stationary; D - Death c) A - Lag; B - Stationary; C - Death; D - Log d) A - Lag; B - Log; C - Death; D - Stationary 6 True/False Each true/false question is worth 1 point. Clearly circle true OR false. 26) True or False: Ribosomes in bacteria consist of two subunits, 30S and 50S. 27) True or False: Leuconostoc mesenteroides produce sauerkraut via the mechanism of cellular respiration. 28) True or False: The efficiency of photosynthesis in biofuel production is limited by the light saturation point. 29) True or False: Transduction is how bacteria replicate their DNA. 30) True or False: Viral DNA in bacterial genome can play a role in bacterial evolution. 31) True or False: All bacteria have capsules. 32) True or False: Endotoxins are lipopolysaccharides that are liberated only through bacterial cell lysis or death. 33) True or False: The trp operon is an example of an inducible operon. 34) True or False: In the absence of lactose, the lacI gene is continuously transcribed. 35) True or False: Telomerase resolves the end replication problem within prokaryotes by constructing telomeres at the end of each chromosome. 36) True or False: Gas vesicles are impermeable to liquid water. 37) True or False: Endospores tend to be less resilient than microbial cysts. 7 Fill in the Blank Points assigned per question. 38) Fill in the Blank: The endolysin Cpl-1 is responsible for degradation of the bacterial cell wall in Streptococcus pneumoniae. A phage which contains this endolysin would be called a ______________ phage. [1 point] 39) Fill in the Blank: Enfuvirtide is a fusion inhibitor drug that prevents HIV-1 from entering host cells by binding to ______________. [1 point] 40) Fill in the Blank [Tie Breaker 1]: Individuals that are deficient in _______________ are often highly resistant to HIV. [1 point] 41) Fill in the Blank [Tie Breaker 2]: ___________ is a glycoprotein found on the surface of HIV-1 and binds to the ___________ receptor to begin host cell entry. [2 points] 42) Fill in the Blank: Reverse transcriptase contains three enzymatic activities: _____________________________, _____________________________, and _____________________________. [3 points] 43) The Escherichia Virus lambda is a really interesting example of a way that a phage can switch between the lysogenic and lytic cycle. The method which controls it is through the use of an operon. Fill in the correct cycle for the given protein (ie when the repressor protein is bound, what cycle is it in) [2 points]: a) λ repressor cI protein : ________________ b) Cro repressor protein : ________________ 8 Given the images of cells under a microscope, provide the type of microscopy shown. Refer to images 2-7 on the image sheet: [6 points, 1 point per image] 44) Image 2: ______________________________ 45) Image 3: ______________________________ 46) Image 4: ______________________________ 47) Image 5: ______________________________ 48) Image 6: ______________________________ 49) Image 7: ______________________________ For 44-47, match the following names with the bacterial cell shape they represent. Fill in the blank with the correct image number. Refer to images 8-11 on the image sheet. [1 point each] 50) Neisseriae : _______________ 51) Tetrads : ________________ 52) Spirochetes : _______________ 53) Streptococci : _______________ 9 Short Answer/Open Ended Points assigned per question. 54) There are several structural characteristics that bacteria, eukarya, and archaea share. List 3. [3 points] 55) Outline the three stages of translation in bacteria. Provide the name of each stage and provide details about the components and process of each. [4 points] 56) You are working to sterilize your materials for your next experiment, and you decide to use autoclaving (heat sterilization) to do so. However, when you run your experiments, you find that bacteria has contaminated your cells. Assuming all other steps of the experiment were completed under sterile conditions, what structure is most likely present in the bacteria? Describe three characteristics of this structure that contribute to the high heat resistance of the bacteria. [2 points] 10 57) Describe a real-world example of commensalism, including the species involved and how the relationship functions. [2 points] 58) You are looking to conduct an experiment on a sample of water that you believe has been contaminated. In order to test this, you need to calculate the density of bacteria in the water using three dilutions. The first incorporates 1 mL of the original water sample and 9 mL of sterile water. The second takes 1 mL of the first dilution and 9 mL of sterile water. The third takes 1 mL of the second dilution and 9 mL of sterile water. Then, you plate 0.1 mL of dilution 2 and 3, and incubate the bacteria. After choosing the appropriate plate, you find that from dilution 2, there are 250 colonies, and from dilution 1 there are 25 colonies on each respective plate. Find the CFU/mL of the original water sample. [2 points] 59) Outline the steps of binary fission. [3 points] 11 60) Describe the endosymbiotic theory and what organelles support it. [4 points] 61) [Tie Breaker 3] The utilization of genetic sequences can be used to understand the evolutionary history of microbes. Some sequences differ in that they are highly conserved across species, while others are highly variable. Why might utilizing both be helpful in determining evolutionary history? [2 Points] 62) In a controlled environment, there exists a large quantity of a certain bacteria. An antibiotic is applied to this and this results in the death of the majority of bacteria. However, after a certain amount of time the population grows back to its original size and the antibiotic is ineffective. What happened and why is the antibiotic ineffective? Assume no presence of extracellular DNA or viruses. [3 Points] 12 63) [Tie Breaker 4] Following the previous question, assuming there is the presence of extracellular DNA, what may be another mechanism in which the scenario occurs? [3 points] 64) [Tie Breaker 5] Provide one example of each the above relationship with at least one of the organisms being a microbe. [4 points] 65) Saccharomyces Cerevisiae is a fungus widely used to make bread. Describe the contribution that this fungus does to help make bread. [3 points] 13 66) In a gram-stain procedure, why does a decolorizer remove the crystal violet from gram-negative bacteria, but not from gram-positive? [2 points] 67) Name 3 species of gram-positive and 3 species of gram-negative bacteria. [6 points] 68) Explain how gas vesicles aid in bacterial cell survival. Please provide two examples of bacteria that utilize gas vesicles. [3 points] 14 69) Describe the role of the lacZ and lacY operon genes in facilitating the use of lactose as an energy source when the lac operon is activated. [3 points] 70) Why is glucose a more preferable energy source compared to lactose? [1 point] 71) The rise in antibiotic-resistant bacteria has contributed to progressing research regarding phage therapy, a potential way of targeting “superbugs” through a viral approach. With the properties of bacteriophages in mind, identify and explain two reasons why phage therapy may be a more efficient treatment for bacterial infections. [2 points] 72) What would happen if DNA replication occurred in the 3’-5’ direction, as opposed to the 5’-3’ direction? [2 points] 15 73) A sample with an optical density of 1.34 is diluted by a factor of 1/20. What is the new optical density of this diluted sample? [1 point] 74) You are a college student in an introductory biology lab studying how different nutrients impact the growth of Chlamydomonas reinhardtii, a type of microalgae that shows potential as a feedstock for biofuel production. You wish to design an experiment to study how the presence of phosphorus impacts algal growth, so you prepare several test tube samples of C. reinhardtii using the lab equipment provided. You first want to determine the initial cell density of your algal samples, so you perform a cell count on a random test tube using a Neubauer chamber. The image below shows the amount of C. reinhardtii cells within a section of the chamber under a microscope. Calculate the cell density of the sample. The dimensions for each individual square are 0.25 mm x 0.25 mm x 0.1 mm. A reference image is provided on the image sheet (image 12). [1 point] 16