# Laboratory Assignment: Virtual Microscopy

Lab Assignment: Virtual Microscopy

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Type your responses to the questions below where indicated. Remember to save your work frequently.

Viewing Magnification, Field of View, and Specimen Size

1. On the UD Virtual Compound Microscope, examine the onion root tip slide at 400X viewing magnification. Ensure that the image is centred. What is the approximate size of an onion root tip cell? Show your work and specify which dimension of the cell (length or width) you are using. (2 marks)

RESPONSE: The dimension of the cell I am using is length. The number of specimen is 11.

The Field of view would be 0.35 mm because we are looking at the onion root tip at 400X magnification.

Actual size= FOV diameter/ # of specimen that can fit across FOV Actual size= 0.35mm/11 specimen= 0.032mm

The actual size of the onion root tip is 0.032mm

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2. Now examine the onion root tip cells at 1000X viewing magnification. What is the size of an onion cell at this magnification? Show your work, and use the same dimension that you did in the previous question. (2 marks)

RESPONSE: The dimension of the onion root tip is length.

The field of view is 0.14mm because we are looking at the onion root tip at 1000X magnification.

Actual size= FOV diameter/ #of specimens that fit across FOV Actual size= 0.14mm/5 specimen= 0.028mm

The actual size of the onion root tip is 0.028mm

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3. Does the actual size of the cell really change from 400X to 1000X viewing magnification? If your answers to the two previous questions were different, how do you account for the difference? (1 mark)

RESPONSE: No the actual size doesn’t really change from 400X to 1000X viewing magnification.

My two answers in the previous questions were different but that could be accounted for the fact that were estimating the amount of species there are in your FOV and for one person could see one amount and another person could see another amount base on what they believe is enough of the specimen showing in the FOV.

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4. What is the approximate diameter of a cheek cell nucleus? Show your work, including a formula and units. (2 marks)

RESPONSE: The dimension that I am using for cheek cell nucleus is width. The magnification I used is 100X, The FOV would then be 1.38mm because I

have a magnification of 100X and the number of specimen in the FOV is 6. Actual size= FOV diameter/ # of specimen that fit across FOV Actual size= 1.38mm/6 specimen= 0.23mm

The approximate diameter of a check cell nucleus is 0.23mm.

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5. What is the approximate size of one of the bacterial cells, including the capsule? This will be more difficult, but you should be able to make a rough (but reasonable) estimate. Show your work, including a formula and units. (2 marks)

RESPONSE: I used the 4X magnification. The bacteria including the capsule was able to fit in the lens 1.25 times, so approximately 0.63 of the cell fits in the lens. Field of view would be 3.5mm because I used 4X magnification Actual size= FOV diameter/ # of specimen that fir across FOV Actual size= 3.5mm/ 0.63= 5.56mm

The approximate size of one bacterial cell including the capsule is 5.56mm.

PLEASE LEAVE THE SPACE BELOW EMPTY FOR TA COMMENTS

Image Magnification and Scale Bars

The questions below refer to the images on the ‘Image Magnification and Scale Bars’ page of the Virtual Microscopy Lab.

6. Samples of three types of organisms (A, B, and C) were collected from a pond. They are shown as they would appear under a light microscope, with the objective magnifications used to view them as indicated. In this particular ecosystem, organisms must be at least 2.5 times bigger, as measured by the longest...

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