Thames & Kosmos TK2 Scope handleiding
Handleiding
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Suppose for a minute that you ate a won-
derful pizza covered with heavily salted
cheese and pepperoni for lunch. After a
while, you might get terribly thirsty. Is
that a coincidence, or is the pizza (or its
topping) responsible for this? To find
out, perform the following experiment
at dinner: Cut a radish into two halves
and sprinkle one half with salt. After
a short time, you will see that small
drops of water are coming out if its cut
surface, whereas the initially moist cut
surface of the other unsalted half slowly
dries out.
A radish is composed of cells, too. A large propor-
tion of the content of a cell is water. When you cut
the radish open, you destroy countless cells and their con-
tents spill out. The sprinkled salt dissolves in the cell liquid
and removes water from the underlying, undamaged cells.
Basically the same thing happens when you eat a salty pizza.
You can surely imagine what effect it would have if a plant
were to be watered with saltwater. As strange as it sounds,
it would dry up even though you were watering it. You can
even observe this under the microscope!
Plants Know How to Stay in Shape
Although a plant loses water, it retains its shape for some time afterward. This is
because plant cells — in contrast to animal cells — are surrounded by two cover-
ings and not by just one.
The Cell Membrane
Both animal and plant cells are enclosed by a so-called cell membrane. This cell
membrane is like a skin that protects the cell from intruders. But, strangely, this
“cell skin” is not completely tight. So you shouldn’t imagine a cell as if all of its
contents were packed into a kind of clear plastic wrap, such as shrink-wrapped
foods in which the packaged contents are completely sealed off in order to
protect the food from germs. But that wouldn’t make any sense because, for ex-
ample, nutrients have to get into the cell and wastes (which are produced in great
quantities in a cell) have to get out of the cell. Surprisingly, water — which is the
most important substance for life on Earth — is able to pass freely through the cell
We humans also consist of a good
60% water? That, however, is noth-
ing compared to jellyfish, which are
over 98% water. Even dried wood still
contains water. When it is burned in the
fireplace, the residual water vaporizes
suddenly and blasts parts of the wood.
That’s why a wood fire “crackles” and
“pops” so nicely.
Life in a Shoebox —
The Plant Cell
5
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Productinformatie
| Merk | Thames & Kosmos |
| Model | TK2 Scope |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 65500 MB |
