Thames & Kosmos Kids First: Biology Lab handleiding

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Thames & Kosmos

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Handleiding

Plant Cells

Onion skin cells

under the microscope

YOU WILL NEED

› 1 Slide, 1 cover slip, pipette, tweezers

› Blotting paper (or paper towel), water, razor

blade, fabric tape, half an onion

HERE’S HOW

1. Get all the materials ready and prepare the

slide: Suction 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.

2 3

EXPLANATION

You will see the elongated onion skin

cells, each one with a round cell

nucleus. In red onions, the walls and

contents of the cell are colored reddish-

purple by a natural pigment. With

white or yellow onions, the

translucent cell walls and contents

appear colorless to slightly yellow

under the microscope.

EXPERIMENT 3

CAUTION!

Razor blades are very sharp, so the first

thing you have to do is to cover one of the two edges

of the blade with fabric tape. That will make the

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

cut and apply the tape.

TIP!

Some specimens are easier to see 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 (as described in the tip on page

13), 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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