Daiva Kuncaite
SCB 201
Prof. Wijasinghe
09/ 22/ 2009
Title: The Microscope and Measurements.
Objectives: learn to convert one unit to another within the main measurements: length, volume,
mass and temperature and change to the scientific notation. Accurately use balance and measure
liquids. Familiarize with the structure of compound microscope and observe the basic plant and
animal cell structures under the compound microscope.
Procedure: In the first part of the lab we discuss the types of microscopes. Since in our lab
practice we are going to use compound microscope we studied its components and the functions
in detail. Firs we tried to focus on the slide with the letter e and later we made own slides and
observe the basic structure of animal and plant cells. For the first plant slide preparation we took
a clean slide, put a drop of water and placed a small piece of Elodea leaf. We covered the slide
with watch glass and try to avoid air bobbles. For the preparation of the second slide we used the
same principle, just instead of Elodea leaf we placed the epidermis of onion. To study animal
cells we used own cheek cells. On the slide we put one drop of iodine. We used clean wooden
stick to scrape the cells from the cheek and dipped it in the iodine. The iodine stained the cells.
We placed the watch glass on top of it and observed the specimen through the microscope. In the
second part of the lab we studied the conversion factors converting one unit from another. We
also determine the accuracy of different laboratory glassware by measuring 100 ml of water
using beaker, then transferring to Erlenmeyer’s flask and then to graduate cylinder. We also
determine the accuracy between the graduate pipette and graduate cylinder by measuring 4 ml of
colored liquid by the graduate pipette and transferring it to the graduate cylinder. We also
determine the temperature of ice water, tap water and ect. using a thermometer.
Results and Discussions: Microscope
The image of the letter e on the slide
The image we see through the microscope
Looking at the image of letter e through the microscope we observe that that image of the letter
is inverted. Switching the magnification to the higher power lenses the image is enlarges but the
field of view decreases.
The image of Elodea cells
Under the lower objectives power we see the rectangular shape, green pigmentation cells. As we
turned the lance to the higher magnification we observed a large central vacuole in the center of
the cell, the cell walls and small chloroplast moving along the wall of the cell. Chloroplast
contain green pigmentation, therefore the cells around the wall has strong green color as going
more to the center the green color is changes to light brown –yellowish.
Daiva Kuncaite
SCB 201
Prof. Wijasinghe
09/ 22/ 2009
The image of the onion epidermis
The color of the onion epidermis cells is off white because the cells don’t have chloroplasts
presented; the shape is longer, irregular rectangular. The walls of the cell are much defined and
the nuclear is placed in the corner of the cell.
The image of the cheek cell
It is hard to find single cell, because cheek cells tend to overlap. However, we can see that cell
has irregular round shape. Instead of central vacuole it has nucleus and small organelles.
Unfortunately, this microscope magnification is not enough to observe more detail layout of
organelles.
Measurments
After measuring 100 ml in the beaker and pouring it into Erlenmeyer flask we still get accurate
results. After we pour the water to the graduate cylinder we were 10 ml off. Therefore, we can
conclude that graduate cylinder is more accurate then beaker or Erlenmeyer’s flask, because it is
the narrowest from all the glassware and liquid disperses not so much.
After transferring 0.8 ml of the colored liquid using 1ml graduate pipette 5 times to the graduate
cylinder, the total volume in the graduate cylinder was 4.2 ml. Theoretically it has to be 4 ml,
because 5×0.8 ml = 4 ml. Therefore, the calculated amount was less than the actual volume,
which leads to the conclusion that the graduate pipette is more accurate than graduate cylinder,
because pipette is narrower and contains less volume which can be measured much more
accurately.
Homework:
1. What is the temperature in C id it is 54 F?
C=(F – 32)×5/9 = (54 F – 32) × 5/9 = 12.2 F = 12 F
2. How many ounces are there in 12 liters?
12 L × 1000 ml = 12000 ml
12000 ml × 0.0338 ounces = 405.6 ounces = 406 ounces.
3. Which is more accurate, a graduated or a volumetric pipette?
Graduate pipette is more accurate.
4. How many cm are there in 15 feet?
15 feet × 0.305 m. = 4.575 m.
4.575 m. × 100 cm. = 457.5 cm. = 0.46 × 103 cm
5. You have just opened your new European cookbook and are ready to create an Epicurean
delight, but the recipe says to set oven at 92 centigrade. At what temperature should you
set your oven (which reads in F)?
F= (Centigrade × 9/5 ) + 32 = 377.6 F = 378 F