Lab_Report_Eukaryotes_Prokaryotes_and_Viruses

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University of Colorado, Boulder *

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MISC

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Biology

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Apr 3, 2024

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docx

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Eukaryotes, Prokaryotes, and Viruses: Structure and Function Danielle Fouche 3/5/24

Instructions: 1. Please read all of the introduction and background information within the investigative manual. a. Once you have done so answer the prelab question BEFORE completing any of the lab’s activities. 2. Once you have completed the prelab questions proceed to the activities of the lab within the investigative manual. a. As you read through the instructions for completing each activity make sure you also: i. Complete any instructions (append photos, etc)/ and answer any questions found in the post lab questions for each activity. ii. Take the photos of your experiments in each activity as directed below . IMPORTANT : Don’t clean-up your lab until you know what portion of the experiment you need to take a picture of. 3. Here is a video that will introduce you to the lab and its main concepts. The student is encouraged to watch it. a. Eukaryotes Prokaryotes and Viruses Prelab Questions 1. There are three panels in the figure below (as labeled). Each panel represents two compartments separated by a semi-permeable membrane. Small solid circles represent water and larger hashed circles represent a solute. In each panel label each side (“Side A” and “Side B”) as either hypertonic, hypotonic, or isotonic. After doing this, illustrate (with an arrow) or state which direction water will move (left- to-right, right-to-left, or neither). 1 © 2016 Carolina Biological Supply Company Neither Isotonic Isotonic Hypotonic Hypotonic Hypertonic Hypertonic

2. IKI (also called iodine-potassium iodide) is a reagent that turns black in the presence of starch. Benedict’s regent is a reagent that turns clear blue in the presence of glucose. As a student in BIO111 you are asked to set up an experiment that has a beaker that has been partitioned by a semi-permeable membrane and you have placed a solution contain 20% glucose on one side of the beaker while on the other side you have placed a solution containing 20% starch. See figure below. Considering this setup answer the following questions: a. After two hours you remove a sample from side A and B and test them for starch and glucose using the IKI solution and benedict’s reagent. Predict, or hypothesize, what you will find for both side A and side B given this scenario. Why did you make that prediction? The glucose will pass through the barrier and register on the starch side, but the starch will not register in the glucose side. I say this because I think starch is more solute than glucose. b. After making your prediction you carry out the test and find that glucose is found on both sides A and B. However, starch is found only on side A. Why do you think this is the case? Answer this question by discussing the molecular difference between glucose and starch. 2 © 2016 Carolina Biological Supply Company

The starch was not able to pass through the barrier the way the glucose was because it was hypotonic, whereas the glucose could pass through because it was hypertonic. c. How does the scenario described in b. compare to a biological membrane? A biological membrane will only let allow molecules of a certain size to pass through, which is like how the barrier worked in this experiment. 3. In Activity 1 of this lab we will be investigating the impact that the surface area-to-volume ratio has on the rate of diffusion. Please read the directions for Activity 1 in the investigative manual. After doing so fill in your purpose and hypothesis statements found under the Activity 1 heading. After completing the lab come back to this section and fill out your evidence/claims and reflection statement. Activity 1 Instructions: 1. Open the investigative manual. Locate all the needed materials supplied in the kit and those you will need to supply yourself. 2. Lay them out in your work area. 3. Read through the entire set of instructions found in the investigative manual for the activity to avoid making mistakes when you go to execute the experiment. 4. Once you have read through the instructions go back to step 1 and begin executing the experiment. 5. Please answer the questions below and/or append appropriate representations of data (photos, graphs, etc). REMEMBER don’t clean up until you have taken the appropriate photos of your experiment as described below. Purpose statement: How will a sample having a larger surface to volume ratio versus a smaller surface to volume ratio affect how well the molecules will pass into the cell? Hypothesis statement: If the potato sample is smaller (smaller surface to volume ratio), then it should take the molecules longer to pass into the cell 3 © 2016 Carolina Biological Supply Company

so the iodine measurement will be larger on the larger potato samples than the smaller potato samples. Evidence/Claim statement: With this experiment the hypothesis was refuted because the iodine passed farther into the smaller potato samples than the larger ones. Reflection statement: I have questions regarding this experiment because the results seemed different than what I’ve learned about surface to volume ratio and molecules passing through. Something with a larger surface to volume ratio should be easier to pass through than one that is smaller. Photo 1 – Activity 1 Take a picture and insert the image(s) of your potato blocks after step 5 of the “Procedure” section in activity 1 of the investigative manual: 4 © 2016 Carolina Biological Supply Company