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Final

BIOL107 Study Guide - Final Guide: Pupillary Distance, Numerical Aperture, Distilled Water


Department
Biology (Biological Sciences)
Course Code
BIOL107
Professor
Christopher Cairo
Study Guide
Final

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Lab #1 Microscopy and Environmental Survey
Possible Exam Questions
1) Increasing the resolution of a microscope can be accomplished by:
a. Increasing the magnification of the ocular lens
b. Increasing the numerical aperture of the objective lens
c. Adjusting the condenser
d. Increasing the wavelength of light
2) Increasing the resolution value of a microscope can be accomplished by:
a. Increasing the magnification of the ocular lens
b. Increasing the numerical aperture of the objective lens
c. Adjusting the condenser
d. Increasing the wavelength of light
3) Parfocal is:
a. The distance between the ocular lens
b. The distance between the lens and the specimen
c. The ability to stay in focus between objective lenses
d. Using the same numerical aperture for each objective lens
4) An organism that is normally fresh water would shrink in salt water because salt water
is
a. Hypotonic
b. Hypertonic
c. Isotonic
d. Salty
5) In hypotonic solutions plant cells become ______________ while animal cells
______________.
a. Turgid, flaccid
b. Turgid, swell
c. Flaccid, shrink
d. Shrink, burst
6) T F The formula for calculating the magnification of a drawing is useful for
determining the size of the specimen.
Answer: False. To read true change “formula for calculating…..drawing” to “proportion of
field of view” or “ocular micrometer”.

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7) T F The specimen must be in focus prior to focusing the condenser.
Answer True
8) T F Interpupillary distance needs to be calculated for each objective lens
Answer - False. To read true change “interpupillary distance” to “resolution”.
9) T F The independent variable tests the effect of the surrounding media in the
algae experiment
Answer False. To read true change “tests the effect of” to “is.” The independent variable
is the variable that is manipulated by the experimenter.
10) T F In the algae experiment the osmotic potential of a solution was kept
constant.
Answer - False. The osmotic potential was the independent variable.
11) T F Distilled water is hypotonic to Mesotaenium
Answer: True. Distilled water is hypotonic for everything
12) T F The three lenses of the microscope are: objective, ocular, diaphragm
Answer: False. To read true change diaphragm to condenser
13) Your supervisor has informed you of her hypothesis that undergraduate students that
drink caffeinated Coca-cola prior to an exam are less successful than those that do
not. You devise the following experiment: 10 Biology 107 students are split into two
halves, one half drink Coca-cola prior to the midterm, the other half do not. Is this a
sound experimental design? Why or why not.
Answer: No. Because you have not eliminated the main variable of interest caffeine. It could
be the sugar in the Coca-Cola or the salt that makes students do worse. The best experiment is
always to remove only one variable in this case caffeine. Therefore it would be better to
test caffeinated vs decaf Coke vs water. In other words, you need a solvent control group.
14) In the above experiment the independent variable is:
a. Coca-cola
b. The group that does not drink Coca-cola
c. The midterm exam
d. The group that drinks Coca-cola

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15) You have designed an experiment to test if the rate of facilitated diffusion of calcium
(Ca++) is affected by the increase concentration of calcium in the media (environment).
Part of your background research finds that Ca++ concentration is normally around
1mM and that proteins called calbindin bind and transport calcium. You can detect
calcium concentrations using a specific fluorescent marker.
a. What would be your independent variable in this experiment?
Answer: The experimental variable would be calcium concentration
b. What would be a control group?
Answer: The control would be physiological calcium concentrations to compare increasing
concentrations to the normal.
16) Using any relevant calculations show what we mean by “empty magnification”.
Answer: If the numerical aperture remains the same between objective lenses the
magnification is increased but the resolution is not.
R = 0.61λ / N.A.
Therefore if N.A. is 0.5 for both the 10x and 100x objective the resolution value is:
(Assume 500nm wavelength).
R= 0.5μm 10x magnification OR 100x magnification
17) Under the microscope you observe a Paramecium that occupies approximately one
third the field of view under the 40x objective lens. The field diameter at this
magnification is 0.5cm. Determine the approximate size of the organism. Your
drawing of the organism is 25mm long, determine the magnification of the drawing.
/ of spec
Answer: Proportion of field of view = diameter of field of view x proportion occupied by
specimen
= 0.5cm x 0.33 = 0.165cm = 1.65mm
Magnification of drawing = size of drawing / actual size of specimen
= 25mm/1.65mm = 15.15x
18) List two ways to determine the size of a specimen on a microscope slide.
Answer: Proportion of field of view
Use of an ocular micrometer
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