Lab Analysis 1 - BIO 206L Exercise 2 Analysis Please answer...

BIO 206L: Exercise 2 Analysis
Please answer the following questions during lab. Keep in mind that you need to work independently. Write in
complete sentences, using proper grammar and spelling when an explanation is required. Be complete yet
concise in your answers. Submit your report as a pdf file on Canvas before the beginning of the next lab.
1. Review the ‘Notebook Guidelines’ posted on LabClicker and evaluate the quality of your lab notes. Did
you follow all of the guidelines? What will you do differently next week?
I followed all of the guidelines presented on Lab Clicker in taking my lab notes. However, next week I will
definitely prepare for lab more thoroughly so that I can do less learning and more experimenting. I will ensure
that I have completely finished a section and answered associated questions before disposing of a slide, and take
as many photos as possible (when using microscopes) for my analysis.
2. How does the “field of view” change with magnification? Relate this to the rule that one should always use
the low-power scanning objective first to locate a specimen. How does the “depth of focus” change as
magnification increases? Are thick (e.g., Elodea ) or thin (e.g., prepared Paramecium ) samples of specimens
preferred at high magnifications?
With a higher magnification, the field of view decreases greatly. As you increase total magnification, you are
able to see less and less of the specimen on the slide. Because of this, it is best to use the 10X objective for
scanning the slide to locate the specimen before magnifying. If you start at a greater magnification, the field of
view is diminished and you will have to scan a greater area to locate the specimen. As the magnification
increases, depth of focus also decreases. For example, thin samples of specimen are preferred at high
magnifications because the microscope can’t focus on the entire depth of the thick sample at high magnification.
With a thick sample at high magnification, only a small layer would be in focus, and the rest of the specimen
would be out of focus.
3. What is Köhler illumination and why is important? What does a numerical aperture (N.A.) indicate? What is
the relationship between resolving power and numerical aperture?
Köhler illumination is the process that is required to adjust the condenser lens and diaphragm so that an ideal
amount of light passes through a specimen equally across the field of view seen through the eyepiece. Köhler is
important because it provides higher contrast and a homogenous illumination. Without it, imperfections in the
illumination of the specimen would be evident, especially in photos. Numerical aperture is a measure of the
amount light rays that are caught by the objective lens. A higher numerical aperture means that more light at a