THE MICROSCOPE LAB - WEEK 5
Correct order of steps to view a specimen at 40X magnification
1) Click power switch to turn on light 2) Adjust light to appropriate brightness 3) Focus at 4X using coarse focus knob 4) Adjust ocular lenses to view one image 5) Focus using fine focus knob 6) Adjust the stage to move the star to the center of microscope view 7) Put 10X objective in place 8) Focus using fine focus knob 9) Put 40X objective in place 10) Adjust using fine focus knob
Arrange the following steps of applying immersion oil in the correct sequence.
1) Focus on the specimen using the 40x objective lens. 2) Turn the objectives to half way between the 40x lens and the 100x lens. 3) Apply a drop of immersion oil directly onto area of the slide you were viewing. 4) Rotate the 100x lens over the microscope slide, and use the fine focus adjustment knob to sharpen the image.
Indicate the correct order of steps as you bring an object into focus under high power.
1) Place slide on stage and secure with stage clips. 2) Turn on the light and center the specimen over the light source. 3) Focus specimen on scanning objective using coarse focus adjustment 4) Rotate to low power objective, then use fine focus to sharpen the image 5) Rotate high power lens into position. 6) Readjust fine focus under high power to produce the sharpest image.
Place the steps to obtain a human cheek cell (buccal) smear in the correct order.
1) Using a sanitized toothpick gently scrape the inside of the cheek 2) Smear the scrapings onto a clean, dry slide 3) Add a single drop of stain to slide 4) Cover with coverslip
Which objective lens requires oil to be applied?
100x
The magnification of the ocular lens is
10x.
Complete the calculations for total magnification produced by various combinations of the eyepiece and objective lenses. Remember, to calculate the total magnification achieved when using a particular objective, multiply the power of the eyepiece by the power of the objective used.
400x: When the high power (40x) objective is used the total magnification will be 400x. 100x: When the low power (10x) objective is used the total magnification will be 100x. 1000x: When the oil immersion (100x) objective is used the total magnification will be 1000x. 40x: When the scanning (4x) objective is used the total magnification will be 40x.
What lens could get dirty with oil if you move the revolving nosepiece in the wrong direction after viewing under oil immersion?
40x
You have successfully focused on an object with the 10x and 40x objective lenses. You have rotated the 100x objective lens into position but are unable to obtain a sharp image by rotating the fine focus adjustment knob. Which of the following is most likely to correct this problem?
Add a drop of immersion oil before rotating the 100x lens into position.
Which feature is present in animal cells, but absent in plant cells?
Centrioles
Which of the three factors affecting image quality is altered by the light source?
Contrast can be altered by light intensity and staining.
A wet mount requires the addition of certain dyes and cell fixatives approximately 12 hours before viewing the specimen.
FALSE
The total magnification achieved using a 10× objective lens with a 10× eyepiece lens is 20×.
FALSE
What is important to remember when using oil immersion?
Immersion oil can only be used with the 100x objective lens but will damage the other lenses.
Correctly labeled animal cell
Left ( 1 ): Nucleus Left ( 2 ): Centrioles Left ( 3 ): Cell Membrane Right ( 1 ): Rough Endoplasmic Reticulum Right ( 2 ): Smooth Endoplasmic Reticulum Right ( 3 ): Cytoplasm Right ( 4 ): Golgi Apparatus Right ( 5 ): Mitochondrion See Answer Image: https://i.imgur.com/zRK4fj2.jpg
Label the image of a compound light microscope using the terms provided.
Left ( 1 ): eyepiece Left ( 2 ): arm Left ( 3 ): mechanical stage Left ( 4 ): fine adjustment knob Left ( 5 ): coarse adjustment knob Left ( 6 ): base Right ( 1 ): rotating nosepiece Right ( 2 ): objectives Right ( 3 ): slide holder Right ( 4 ): stage Right ( 5 ): power switch Right ( 6 ): light source See Answer Image: https://i.imgur.com/HEzHxq2.jpg
Correctly labeled human epidermal cell (microscope view)
Left: Nucleus Right ( 1 ): Cell Membrane Right ( 2 ): Cytoplasm See Answer Image: https://i.imgur.com/wNLSioj.jpg
How do the coarse and fine focus knobs work on a brightfield microscope?
The focus knobs move the stage up and down, allowing the user to move the slide into focus.
Why is it easier to locate your specimen at a lower power objective?
The low power objective makes it easier to find the specimen on the slide
What is the advantage of using a wet mount?
The motility of a specimen can be viewed under a microscope. The specimen can be viewed as living cells.
Why should the fine focus knob typically be used with the 10X and 40X objective lenses?
The slide should be close to in focus after focusing at the 4x objective. Focusing with the coarse focus knob would result in too large a change in focus.
Why was a stain added to the human epidermal cells from the cheek smear prior to microscopic observation?
The stain was used to add contrast and make the cells easier to view.
What is the total magnification of a specimen using the 40X objective?
Total magnification is 400X.
When preparing a wet mount specimen for viewing, the specimen should be covered with
a coverslip.
The mechanical stage upper knob causes the stage to move
back and forth.
Pond water can contain many types of organisms. Which of the following are you most likely to find in a pond water sample? Please select all that apply.
bacteria algae rotifers protozoa
The __________ causes the stage to move upward or downward.
coarse adjustment knob
The fine adjustment knob on the microscope
fine-tunes the focus.
The coarse adjustment knob on the microscope
locates the focus plane.
A change in what component of microscopy influences the apparent size of the objects being viewed?
magnification
What does the term motile mean?
movable
Which objective lens provides the highest total magnification?
oil immersion
Using oil immersion is useful because
oil immersion increases the resolving power of the specimen.
The mechanical stage lower knob causes the stage to move
right and left.
The objective lenses of the compound light microscope are attached to the
rotating nosepiece.
Which objective lens provides the least total magnification?
scanning
What is the advantage of starting with the 4X objective before moving to the 10X and then the 40X objective?
the field of view is larger, and it is easier to focus
Which of the following items will you need to make a wet mount?
transfer pipette clean slide tweezers cover slip
