Describe what steps you would take to observe mitosis from root tip tissue under the microscope
1. Cut 1cm from the tip of a growing root tip 2. Put a boiling tube of 1M HCl into a 60 degree celsius water bath and add the root tip for 5mins 3. Rinse the root tip in distilled water 4. Use a mounted need to smear 2mm from the end of the root tip
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tissue onto a slide 5. Add a drop of stain 6. Place a cover slip over the slide by lowering it slowly using a mounted needle 7. Push down on the cover slip and squash the tissue, and don't smear the cover slip sideways
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What equipment is usually used to rinse the root tip tissue after it's been incubated in the HCl?
A watch glass and tweezers
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Why is a stain used when preparing the slide?
It will allow you to see the chromosones more easily under the microscope
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If an ethano-orcein stain is used, what type of acid does the root tip tissue have to incubated in?
Ethanoic acid
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Why is the coverslip pushed down onto the cells before observing under the microscope?
It makes the cell layer thinner hence easier for light to pass through and to observe under a light microscope
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How does smearing the cover slip sideways affect the observation?
You can damae the chromosomes by doing that
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How is a microscope used?
- The prepared slide is clipped onto the stage - Set the objective lens to he lowest magnification - use the coarse adjustment knob to bring the stage up to just below the objective lens - then use the coarse adjustment knob again to move the stage
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downwards until the image is roughly in focus - use the fine adjustment knob to focus the image
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How can you increase the magnification of the image?
By changing to objective lens to a higher value lens
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What is the mitotic index?
It is the proporion of cells undergoing mitosis in a tissue sample or field of view in a tissue sample
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What is the formula for the mitotic index?
mitotic index = number of cells undergoing mitosis/total number of cells
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In what three situations would you expect a high mitotic index?
Cell growth, cell repair or cancerous growth
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What is an artifact?
matter that you can see down a microscope that aren't part of the cell or specimen that you're looking at
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What is an example of artifacts?
- Dust - Air bubbles - Finger prints
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When are artifacts usually caused?
When preparing the temporary mount and squashing and staining your sample
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Why are artifacts more common when using electron microscopes?
There is more preparation involved in the assembly of the temporary mount
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Other cards in this set
Card 2
Front
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Back
tissue onto a slide 5. Add a drop of stain 6. Place a cover slip over the slide by lowering it slowly using a mounted needle 7. Push down on the cover slip and squash the tissue, and don't smear the cover slip sideways
Card 3
Front
What equipment is usually used to rinse the root tip tissue after it's been incubated in the HCl?
Back
Card 4
Front
Why is a stain used when preparing the slide?
Back
Card 5
Front
If an ethano-orcein stain is used, what type of acid does the root tip tissue have to incubated in?
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