Thames & Kosmos Kids First: Biology Lab (V 2.0) handleiding

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Thames & Kosmos

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Handleiding

Onion skin cells under

the microscope

You will need

– Slide

– Cover slip

– Pipette

– Tweezers

– Blotting paper or paper towels

– Water

– Razor blade

– Electrical tape

– Half an onion

Here’s how

1. You can also make a slide preparation of the

onion epidermis yourself. Get all the materials

ready and prepare the slide. First, suck up a

little water with the pipette and place a drop on

the center of the slide.

2. Now use the razor blade to cut a small square

section out of the skin of the onion. Remove

the square with the tweezers and place it in

the water droplet you placed on the slide.

3. Carefully position a cover slip over the water

droplet. If there is too much water under the

cover slip, just blot up the extra water with

blotting paper or a paper towel.

4. View the slide like you did in Experiment 2.

Compare it to what you saw in that

experiment.

WARNING! Razor blades are very sharp, so the first thing you

have to do is cover one of the two edges of the blade with

electrical tape. See page 10 for instructions. This will make

the blade a lot safer to handle. Have an adult help you cut and

apply the tape.

EXPERIMENT

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Some specimens are easier to see

under the microscope if you dye

them. It’s easy to do — try it with a

drop of red or blue ink. Let the ink

get pulled under the cover slip

(using the method described in the

tip on page 14), wait a few minutes,

and then add clean water and let it

get pulled under the cover slip. Then

you can study the prepared specimen.

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