BIO 126 LEXAM I Sample exam 5__________________________________ __________________________________PRINT YOUR NAME (Last, First) Lab meeting time (Day, time, E or W)___________________________________TA’S NAME___________________________________SignatureINSTRUCTIONS: BIO 126 L EXAM I has 11 pages, and 43 questions.There are a total of 200 points, accounting for 20% of your final grade.Place your name at the top of each page and check that your exam is complete.ANSWER ALL QUESTIONS.Be brief and precise in your answers. DO NOT RAMBLE!You must show your calculations where asked.Copying and all other forms of cheating will be met with the appropriate disciplinary action.In case you dispute the answer that is deemed correct, you MUST first submit to your TA your question and the reason that you think your answer is the best (not just right, but the best of the answer choices) along with references that support your viewpoint. This must be done within 1 week after the exams are returned.YOU MUST HAND OVER YOUR COMPLETED EXAM TO YOUR TA WHEN LEAVING THE ROOM 1Printed Name (Last, First) __________________________________ Choose the BEST answer; circle the appropriate answer, fill-in the blank, answer true or false, or write a brief answer as necessary. 1. (6 points) Indicate the appropriate safe disposal containers for the following items in the lab.Choose one (BEST) of the following: (A) test tube racks in the metal pans, (B) plastic beakers lined with biohazard bags, (C) plastic beaker with soap solution, (D) disinfectant jar, (E) trash-cans lined with biohazard bags, (F) regular trash-cans.a. Glass slide used for mixed cell suspension __________b. Paper wrapping of the cotton swab used to make a lawn of E. coli __________c. Culture of Vibrio natriegens from the cuvette (after you took its O.D.) __________d. Glass beads used to spread bacterial cells __________e. Test-tube containing a bacterial culture __________f. Plastic micropipette tips (yellow ones) used for plating __________2. (3 points) A parfocal system of lenses has the advantage ofa. making the focal length of all lenses the sameb. increasing the depth of focusc. increasing the brightness of the image by pre focusing the light through an amplifying lensd. allowing all of the objective lenses to be approximately focused in the same horizontal plane3. (3 points) The compound light microscope used in labs (BIO 126L) can be used to observea. Amino acids, nucleus, viruses and bacteriab. Bacteria, yeast, paramecium and RBCsc. Proteins, nucleic acids, viruses and bacteriad. Ribosomes, nucleus, bacteria and RBCs4. (3 points) Under which conditions is it necessary (useful) to use phase-contrast on your microscope?a. When using a high dry objectiveb. When looking at eukaryotic cellsc. When looking at unstained cells2Printed Name (Last, First) __________________________________ 5. (2 points) True / False An objective with a shorter focal length needs less light to view the sample properly (as compared to one with longer focal length).6. (4 points) What is the total magnification of the specimen when viewed with a microscope of the following parameters: 600 nm light source, 15X ocular lens and 40X objective with a numerical aperture of 0.5?Total magnification: _______________7. (6 points) What is the resolving power of a microscope that uses a light source with a wavelength of 400 nm, 10X ocular, and 100X objective (numerical aperture 1.0)?Use the units written below. (No credit for incorrect units)Formula: _______________________ Resolution: _______________________ micrometers8. (4 points) Using a light microscope with a resolving power of 0.3 m, a 10 X ocular and a 100 X objective lens, would you be able to see clearly two objects separated by (a) 400 nm, (b) 200 nm? Explain your answer in less than 30 words.(a) 400 nm(b) 200 nm9. (2 points) True / False E. coli, stained with crystal violet, will appear as purple rods when viewed under a light microscope.10. (4 points) You have 3 bottles containing different liquids. The refractive indices of these liquids are 0.8, 1.4 and 2. If you had to choose one of these liquids (in place of immersion oil)for viewing your gram-stained sample, which one will you choose and why? Answer in less than 30 words. Refractive index of glass is 1.52.3Printed Name (Last, First) __________________________________ 11. (4 points) In less than 20 words explain why we sterilize the medium used for growing microorganisms?12. (4 points) One of the several medium used in labs to grow microorganisms is nutrient agar. It contains peptone, beef extract and agar. Answer the following questions for nutrient agar.a. Mention one component in this medium that is used as a carbon source?__________________ b. Is this an example of a synthetic medium or of a complex medium?__________________13. (4 points) Mention 2 characteristics that you have used so far (and are listed in your lab manual) that can be used to identify a pure culture.a. ____________________________ b. ____________________________14. (6 points) One of the main objectives of an introductory microbiology lab is to learn how to isolate a pure culture of a microorganism. Mention 2 lab techniques you have performed so far by which you can isolate a pure culture starting with a mixed culture.a. ____________________________ b. ____________________________15. (3 points) The purpose of alcohol in gram-staining technique isa. to chelate excess iodineb. to increase the uptake of the counterstain by dehydrating the cells with ethanol c. to wash crystal violet from all areas where it is not tightly boundd. to properly dry the cells so they will adhere well to the glass slide16. (6 points) In the space provided below draw and describe in less than 15 words what a staphylococcal arrangement of cells would look like.4Printed Name (Last, First) __________________________________ 17. (4 points) In gram-staining procedure one of the first things you do is make a smear of the organism. Included in the preparation of the smear are two steps: air-drying the sample and heat fixing. Why is it important to air-dry the sample before heat-fixing? Answer in less than 20 words.18. (4 points) Assume that you are viewing a gram-stained field of red (pink) cocci and blue (purple) rods through the microscope. Based on this observation you can safely conclude thatyou a. have an old bacterial culture b. forgot to heat fix the specimen c.