Lab 0 Assignment Ali Khelil 101258560 (3)

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Carleton University *

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1103

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Biology

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Oct 30, 2023

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Fall 2023 Lab 0 – Lab Skills: Basic Biology Lab Techniques BIOL 1103 Lab 0 Experimental Assignment Full Name: Ali Khelil Student #: 101258560 Lab section: Thursday 1:35 A14 Although the experimental work will be completed in pairs, all work submitted must be completed individually. It is important that you do not copy from the lab manual or from each other. DO NOT plagiarize! Remember to properly cite and reference any external sources used (refer to Appendix 1 for guidelines). Unless otherwise specified in the question, all answers should be written using complete sentences, paragraph style. Part 1: Practice Using a Microscope 1. What is the make and model of your microscope you are using for the Lab 0 Experimental session? Make: Olympus Model: CX31 2. Observe the letter first using the 4X, then 10X, and finally the 40X lens. Draw the image of your letter exactly as you see at each magnification in the spaces below. ( You may insert a picture of the diagrams from your lab notebook ). 3. How does the image of the letter change when viewed in the microscope? The letter e gets closer and closer until you can’t see the complete letter e. 4. What is special about a parfocal lens? What does it allow you to do (or not have to do)? What’s special about a parfocal lens is that once the image has been focused using a lower power objective. When you’re using a higher power objective only minor adjustments could be made by using the fine focus.

Fall 2023 Lab 0 – Lab Skills: Basic Biology Lab Techniques BIOL 1103 5. Assume you are viewing a letter with a hat on top (e.g., ê) and are only interested in the hat. As you increase magnification, are you still able to see the hat without making any adjustments to the microscope other than fine focus and light intensity? Explain what you need to do to continue observing the hat up to the 100X objective lens. You won’t be able to see much if you don’t adjust the magnification or light intensity. If magnification isn’t set up properly the resolution won’t be good at all. If you don’t change your light intensity, then your specimen will be either too bright or too dark. What you need to do to continue observing the hat at 100X is to first add immersion oil to the microscope or else you won’t be able to see anything on the 100X objective lens. Once you add the oil you need to adjust the magnification and light intensity so you can see a clear and decently bright image of the letter with the hat on it. Once you have a good resolution you adjust the x and y position of your sample so you can see the hat of the letter (note: you may not be able to see the whole top hat). Part 2: Preparing a Wet Mount 6. What is the name of the bacteria and the yeast in the culture you observed? Use proper scientific format. Bacteria: Bacillus Thuringiensis Yeast: Saccharomyces Cerevisiae 7. What is the unique step required to use the 100X objective lens? Why is this important? You need to add immersion oil to the microscope or else you won’t be able to see anything on the 100X objective lens. 8. Using complete sentences, write a detailed description of the general characteristics of the bacteria and yeast cells you observed. In your written description, provide the scientific names of the species you observed. Include details regarding: the shape, texture, and colour of the cells using what specific stain, describe the general thickness of the cell wall and/or the plasma membrane, and which (if any) organelles were visible. The Bacillus Thuringiensis is a cylindrical bacterium that’s dark in colour. No organelles were visible using the 40X scope. The Saccharomyces Cerevisiae was circular in shape and although light on the cell wall the inside was darker when looking through the 40X and the 100X scope.

Fall 2023 Lab 0 – Lab Skills: Basic Biology Lab Techniques BIOL 1103 9. Were you able to resolve the cell membrane in both the bacterial and yeast cells observed? Explain why or why not. The Bacillus Thuringiensis has a cell membrane in the middle of the cell. Although it’s small you can see a thick area in the middle of the cylindrical bacteria is the cell membrane. The cell membrane of the Bacillus Thuringiensis looks like a huge roll of string scrambled up. The Saccharomyces Cerevisiae had a dark circular middle part of the cell. Inside the cell wall would be where the nucleus is. 10. If you were including a drawing of your specimens in a lab report, state a correct title for your drawing (refer to Appendix 2). Whole mount of Saccharomyces Cerevisiae 11. Where would the title be placed relative to your drawing (i.e., above, below, or beside)? Below the drawing. Part 3: Calculating the Size of your Specimen 12. What is the purpose of using conversion factors when calculating the actual size of your specimen? The ruler on the microscope is unitless. So, to find out the size of the specimen you’d have to convert the unitless measurements to micrometers. 13. Using the ocular micrometer, calculate the actual size ( length ) of the two cells you observed. Show one complete sample calculation. o.u.= 5 1.0 um/o.u. x 5 o.u. = 5 um Part 4: Practicing Pi-pump Use 14. What are the weights of each of your experimental tubes (i.e., tubes 2-5) after adding the appropriate volumes of solution? Include relevant units. Tube 2: 7.260g

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Fall 2023 Lab 0 – Lab Skills: Basic Biology Lab Techniques BIOL 1103 Tube 3: 7.314g Tube 4: 11.264g Tube 5: 14.073g 15. Do the weights of your experimental tubes align with the expected weights of each tube? Briefly outline 3 factors that could affect pipetting accuracy and precision. The weights of the experimental tubes align with the expected weights of each test tube. 3 factors that could affect the pipetting accuracy and precision is air trapped while taking in water, the squeezer not being squeezed with the same amount of force for each pipetting, and water splashing out of the test tube when you’re pouring the water from the pipe t to the test tube. This assignment is due 1 week after completing your Lab 0 session, but must be submitted to Brightspace on the hour prior to your next session (i.e., 8 AM or 1 PM). While this assignment is not for marks, one bonus mark will be added to your final lab mark upon successful completion of Lab 0 (must attend experimental session, complete of the pre- lab quiz, and assignment). IMPORTANT: There is NO tutorial associated with Lab 0. Your next session is Lab 1 in two weeks (refer to schedule in Brightspace).