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Cells of the egeria with chloroplasts
Did You Know?
Some gardeners feed their plants
with carbon dioxide. Greenhouses
make it possible to pamper plants
especially well. Sufficient heat and
light usually make plants thrive
more than in the open field. In ad-
dition, some gardeners "fertilize"
their plants in greenhouses with the
gas carbon dioxide, which the plants
need in order to produce dextrose
with light and water.
Ripe and unripe tomatoes
Chlorophyll
You will find chloroplasts in all green plant parts. It is especially easy to study
the chlorophyll in the leaves of some typical aquarium plants because the
leaves are only two layers thick. Different species of egeria are frequently used
in aquariums (elodea is another scientific name for it). Maybe you know some-
one who has an aquarium who is willing to give you a couple such leaves. Or
you can ask for some in a pet or aquarium store.
To prepare the object, you will need:
• a slide and a cover slip
• water and the pipette
• the tweezers
• a small egeria leaf
Using the tweezers, pinch off a small leaf from the egeria and place it into a
drop of water on the slide. In the six-sided cells, you will find the round chlo-
roplasts. You will probably need to move the focus adjustment of your micro-
scope back and forth a bit in order to see one of the two layers of cells really
clearly. Often, in this specimen you can also observe how the chloroplasts in
the cell move about in circles.
On Green and Red Tomatoes
The chloroplasts of plants are not just fantastic energy converters — they're also
able to metamorphose at a given time. Very many fruits are still green as long as
they are unripe. Apples, tomatoes, cherries, or grapes change their color over the
course of ripening. Through the altered color, often supported by emitted aromas,
the plant signals that its ripened fruits are now suitable for consumption. Why
does it do that? To have the seeds hidden in their fruits distributed by animals, of
course. They eat the seeds with the fruits, are not able to digest them and then
drop them somewhere else together with the other remains of their digestion. In
this way, the plant is able to provide their progeny with a sunny place to grow and
prosper without budging from their fixed location.
Here too, the green color of the fruits comes from the chloroplasts in the cells of
the fruits. As the fruits slowly become ripe, the chloroplasts gradually transform
into granules of a different color, or chromoplasts. In so doing, they often change
shape, too, resulting in a great variety of chromoplasts to discover out there.
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