Investigation 1: Observing Plant and Animal Cells

Transcription

1 SNC2D Tissues, Organs and Systems Investigation 1: Observing Plant and Animal Cells Part 1: Examining Onion Cells 1. Obtain a small section of onion. Use tweezers to pull off a thin transparent layer of cells. 2. Prepare a wet mount of the onion cells by placing the specimen in the drop of water on a slide and lowering the coverslip gently at an angle over the specimen as shown in the diagram below. 3. Add a drop of iodine stain to the slide at one edge of the cover slip. Place a piece of torn paper towel against the opposite edge of the cover slip. The stain should move under the cover slip toward the paper towel. This is called wicking. When all of the cells are stained, remove the paper towel. 4. Place the slide carefully onto the stage of the microscope and observe the cells under low, medium and high power. 5. Estimate the number of cells that would fit across the field of view and calculate the size of a cell: width of the field of view cell size= number of cells that would fit across 6. In the space provided on the Cell Scale Diagrams sheet, create a labeled scale diagram of an onion cell. (The diagram should take up the majority of the space provided). Include the magnification under which it was viewed and your estimation of the size of the cell. **Use your scientific drawing checklist. 7. Take a look at the prepared Elodea Cell slide as well as take a look at the picture displayed on the whiteboard. Make observations on how the onion and Elodea cells are similar and different. Part 2: Examining Cheek Cells 1. With a sterile cotton swab, gently rub the inside of your cheek near your molars to obtain some saliva containing cheek cells. 2. Prepare a wet mount of the cheek cells as above, this time adding methylene blue stain. 3. Place a slide on the microscope and observe the cells under low, medium, and high power. 4. Estimate the number of cells that would fit across the field of view and calculate the size of a cell. 5. In the space provided on the Cell Scale Diagrams sheet, create a labeled scale diagram of an onion cell. (The diagram should take up the majority of the space provided). Include the magnification under which it was viewed and your estimation of the size of the cell. **Use your scientific drawing checklist 6. When you are finished with your slide, bring it to the front of the room and place it in the disinfectant bowl.

2 Cell Scale Diagrams Figure 1 - B Figure 2 - A

3 Analyze and Evaluate: 1. What structures were you able to identify in the onion cells? 2. What structures were you able to identify in the cheek cells? 3. What was the most obvious difference between the two types of cells? 4. Is an onion cell a plant or animal cell? How do your observations support your choice? 5. What difference, if any, did you notice in the cells before and after they were stained? Why were you advised to stain the cells? Apply and Extend 6. What structures were you able to see in both the plant and animal cell? 7. What structures were observed only in the Elodea cell? Give reasoning for why these structures were not found in the onion cell. 8. Would you expect all animal cells to look the same? Explain your answer. 9. If you were to complete this activity again, what improvements would you make? Conclusion 10. Write 2-3 sentences on what you learned from this lab activity. What to Submit: o Completed specimen drawings (fully labeled use your checklist) o Completed answers to questions 1-10 o Submit the Scientific Drawing Checklist completed by your lab partner. o Submit the marking rubric with your lab.

4 SCIENTIFIC DRAWING CHECKLIST (Use U or Y to indicate whether each is done correctly or not.) ARTIST S NAME: MARKER S NAME: ë Drawing done on blank paper. ë Drawing done with sharp pencil. ë Firm clear lines (no sketching). ë No shading/colour used (stipples allowed). ë Only relevant & easily seen details are included. ë Large drawing (Ω the page). ë Labels are neatly printed. ë Labels all located to the right of the drawing. ë Labels listed in an even column. ë Label lines are parallel & done with a ruler. ë Label lines do not cross. ë Name & date located in top right corner. ë Appropriate title located at the top. ë Title underlined. ë Total magnification located in bottom right corner. Quality of drawing: Comment TOTAL L /20

5 SNC2D:Biology AssessmentRubric Lab:ObservingAnimalandPlantCells Name: Date: /100 SuccessCriteria %(Level4) 70 79%(Level3) 60 69%(Level2) 0 59%(Level1/NI) KnowledgeandUnderstanding Understandingof Demonstrates thorough understandingofthe Demonstrates considerable understandingofthe Demonstratessome understandingofthe Demonstrateslimited ornounderstandingof the ThinkingandInvestigation LabSafetySkills equipmentwithahigh degreeof Making Consistentlymakes equipmentwith considerable Regularlymakes equipmentwithsome Occasionallymakes equipmentwithlimited ornoappropriateness and makecompleteand precise Communication Useofconventions,vocabulary andterminology Expressionofideasthatsupport conclusions Making specimen terminologywitha highdegreeof accuracy withahighdegreeof Consistentlymakes terminologywith considerableaccuracy withconsiderable Regularlymakes terminologywithsome accuracy some Occasionallymakes terminologywith limitedornoaccuracy withlimitedorno makeaccurateand completediagrams accordingto Application Identificationofpotential Consistentlyidentifies Regularlyidentifies Occasionallyidentifies applicationsoftheresultsofan potentialapplications potentialapplications potentialapplications torealworldsituations torealworldsituations torealworldsituations activitytorealworldsituations identifypotential applicationstoreal worldsituations