Biology Cell Unit Homework Packet #1

Transcription

1 Name DUE: Biology Cell Unit Homework Packet #1 Hour HW #1 Microscope Questions Exploration Drawing Lab Post-Lab Questions / 5 possible points

2 Homework #1: Microscope Exploration Lab When working with a microscope, it is important to follow these directions: Setting Up 1. Carefully take out the microscope using two hands (one hand on the arm and one hand on the base ). 2. NEVER MOVE THE MICROSCOPE BY SLIDING IT ACROSS THE LAB BENCH. 3. Remove dust cover. 4. Plug in microscope into electrical outlet. 5. Turn on microscope. Focusing 6. Lower stage to lowest point using coarse focus (large knob). 7. Place slide on stage and hold slide in place using stage clips. 8. Turn objective to lowest setting (4X). 9. Locate object using eyepiece (10X) and coarse focus. NOTE: The total magnification can be found by multiplying the magnification of the eye piece (10X) and the magnification of the objective. Do this now for low power. 10 X 4 = 40 (total magnification) Draw the letter E in the circle below. This circle represents what you see in the microscope or your field of view. If the E fills the entire circle in the microscope, draw the e big enough to fill the circle (as you have observed). This is called drawing it to scale.

3 Focusing continued 10. Focus the letter e using the microscope. 11. When you have located the object, rotate the eye piece to medium magnification (10X). 12. Adjust the focus by using the fine focus knob (smaller knob). 13. Once it is in focus. Move the letter e : up and down, side to side while looking through the eyepiece QUESTION: When moving objects on a slide, how do they appear to move? The objects move in the opposite direction. 14. Look at the microscope picture at the end of this lab and find the diaphragm. While looking through the eyepiece, rotate the diaphragm dial. QUESTION: What does the diaphragm do? The diaphragm adjusts the amount of light that passes through the object. 15. Repeat steps 10 and 11 for high power (40X). Cleaning up 16. Return to the low power objective. 17. Lower the stage using the coarse focus knob. 18. Carefully remove the slide. 19. Turn off the microscope. 20. Unplug the microscope. 21. Place the dust cover over the microscope. 22. Using two hands, return the microscope to the cabinet. QUESTION: When focusing objects under medium or high power, which focus knob are you supposed to use? Use the fine focus knob. DON T FORGET TO DO THE LAST TWO PAGES!

4 Lab Continued: DAY Two Drop of water Pond Water Critters 1. Preparing a wet-mount you must place one drop Cover Slip of pond water in the middle of the slide 2. Place a cover slip over the slide. 3. Place on the stage of your microscope, BE SURE THAT THE OBJECTIVE IS ON LOW POWER! 4. Looking at the stage use the coarse adjustment *always rinse and dry your slide and cover slip before the end of class* knob to bring the stage all the way down. 5. While looking through the eyepiece adjust the stage using the coarse adjustment until the objects appear. You may then use the fine adjustment to further focus on one particular organism. (only use coarse adjustment knob on low power) 6. To change from one power to another, turn the objective. Then re-focus using the FINE ADJUST ONLY! 7. You should be able to locate several specimens from both plant-like and animallike quite easily. Plant-like could be any examples of algae that you find. Label any obvious cellular structures that are evident that you may already know from 7 th grade such as cell wall, nucleus, chloroplasts, cytoplasm and cell membrane. Record a few notes concerning what you have located, this could include: name, size, condition, organizational arrangement, color, etc. Then draw one of your examples in the space provided that includes some detail of the organism you found. Notes: Draw Plant-like Name if known Magnification Color Other

5 Animal-like are often going to be protozoa and small multicellular organisms that will be a bit more difficult to locate. Many examples of this group will be unicellular and most likely very small. In many cases, specimens will be fast moving and difficult to keep in the field of view and focused. Viewing tips: prepare slides with a bit of algae or something to act as a net, trapping protozoa into a confined space for easier viewing. Record a few notes concerning what you have located, as mentioned above. Then draw one of your examples in the space provided that includes some detail of the organism you found. Notes: Draw Animal-like Name if known Magnification Color Other

6 POST- LAB QUESTIONS: Let s pretend that you and your lab partner are told to examine a slide of an onion root tip under medium power. Using your expertise in properly working with microscopes, answer the following questions in complete sentences. A. Describe the focusing process. Be sure to tell me the position of the stage when you start, the order of objectives that would be used, and which focus knobs would be used for each objective. Lower the stage Start with low power using coarse adjustment knob. Adjust to medium power. Use fine focus knob. If using high power, switch objective and use only fine focus knob. B. When you observe your onion root tip cells, what is the total magnification for what you see? (Remember, the magnification for the eyepiece is 10X and the magnification for low power is 4X, medium power is 10X and high power is 40X.) Please show your work. Eyepiece Medium Power Total Magnification 10 X 10 = 100X C. You notice that the onion root tip cells appear to be very dark. What could you do in order to make the cells more visible? Adjust the diaphragm to allow more light to shine through.

7 D. Label the microscope with the following terms: objectives, eyepiece, arm, coarse focus, fine focus, stage clips, stage, base. Eyepiece Objectives Arm 9. Stage Clips Stage Coarse Adjustment DIAPHRAGM Fine Adjustment Base