1 Biol 204 Lab Worksheet Name Lab 1: Microscopes & Cells Section The following worksheet is for you to fill in during lab and corresponds to the questions in your lab manual that you are responsible for answering. Turn in these sheets instead of tearing the pages out of your manual. This worksheet is due at the beginning of your next lab period. Ex. 1: Parts of the Microscope (pp. 2-5) 2 a. Is your microscope monocular or binocular? What is the magnification of your ocular(s)? b. What is the magnification of each of your objectives? List them in order of increasing magnification. c. Is your microscope equipped with phase-contrast optics? Does your microscope have a mechanical or stationary stage? d. Describe the light system (light source & adjustment) for your microscope. Ex. 2: Basic Microscope Techniques (pp. 5-9) 2 m. In what direction does the image in the ocular move? n. Is the image in the ocular inverted relative to the specimen on the stage? q. Is the working distance greater with the 40X or the 10X objective? 3 a. What is the total magnification of the specimen as the microscope is now set? b. What would be the total magnification if the ocular were 20X and the objective were 100X (oil immersion)? 2 4. Note: We will not have you measure the width of the field of view. Instead we will give you the measurements for the divisions on the oculer micrometer (the small ruler that appears in one of your oculars). e. 4X: 1 div = 25?m; 10X: 1 div = 10?m; 40X: 1 div = 2.5?m; 100X: 1 div = 1?m f. What is the relationship between the size of the o.m. and the magnification? 5. b. Are both threads in focus at the same time? c. Using the 10X objective? Does the 4X or 10X objective have a shorter depth of field? d. Does a deeper plane or more superficial plane come into focus first? e. Does the 10X or 40X objective have a shorter depth of field? Ex. 5: The Organization of Cells Lab Study C ? Multicellular Organisms (pp. 18-19) Plant Cells Refer to page 9, Ex. 3, #3a-d for preparing your Elodea wet mount 3. What 3 structures observed in Elodea are found in plant cells but not animal cells? Extra Question: Use the data below to explain why the light waves reaching your eyes give chloroplasts a green appearance. 3 Animal cells 3. Sketch one of your cheek cells below and label the cell membrane, nucleus and cytoplasm. Don?t just copy the lab book sketch. Extra Question: Epithelial cells such as this secrete an extracellular basement membrane on their basal/apical (circle one) surface. What is the function of this basement membrane? Lab Study D ? Unknowns (pp. 19-20) Table 2. Characteristics of Organisms Found in Pond Water: Unknown Means of Locomotion Cell Wall (+/-) Chloroplasts (+/-) Organization 1 2 3 4 Questions for Review (p. 20) 2. Describe at least 2 types of materials or observations that would necessitate the use of the stereoscopic microscope. Why do they require use of stereoscopic microscopy? 3. Name three characteristics of eukaryotic cells that are not found in prokaryotic cells. 4 4. b. How are structures that are unique to plants important to their success? Additional Questions: 1. What is/are the function(s) of the condenser lens? 2. The final lenses that focus reflected light waves from your specimen are not part of the microscope, but rather are biological (i.e., beneath your corneas). Onto what biological surface is the focused ?image? ultimately projected? Optional Reference Material: Here are some useful and otherwise interesting websites on light microscopy. They vary from quite basic to somewhat advanced and are provided as potentially useful reference sources, not as required readings. http://www.jic.ac.uk/microscopy/intro_LM.html http://www.geog.ucl.ac.uk/about-the-department/support-services/laboratory/light- microscopy/bright-field-microscopy http://dwb4.unl.edu/Chem/CHEM869K/CHEM869KLinks/www.ruf.rice.edu/~bioslabs/methods/ microscopy/microscopy.html http://arnica.csustan.edu/boty3100/microscope.htm http://science.howstuffworks.com/light-microscope1.htm 5 http://en.wikipedia.org/wiki/Optical_microscope http://www.southwestschools.org/jsfaculty/Microscopes/Magnification.html Lelena Avila 204 Lab Worksheet
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