In order to survive, plants need to
carry out photosynthesis, and for that they need the water and
minerals they acquire from the soil by means of their roots.
The job of the roots is to spread rapidly underground like a net
and draw up water and minerals. Plant roots, despite their
delicate structure, also enable plants that in many cases weigh up
to tons to hold on to and fix themselves in the soil. The
soil-gripping nature of roots is most important, because it
prevents landslides and the fertile upper layers of soil from
being washed away by the rain.
Roots
need no equipment for all this. They have no engine to
provide the power to start the process of water drawing.
Neither is there any equipment to pump the water and minerals to
the stem meters away. But roots can spread over a wide area and
draw water. So, how do they do it?
How
Does This System Work?
A
typical red maple tree growing in a humid climate may lose as much
as 200 liters of water per day. This represents a serious loss for
the tree. This water needs to be replaced immediately if the plant
is to survive. Thanks to the flawless root system plants have,
every drop of water that evaporates is replaced.1
The
roots, which spread down into the depths of the earth, send the
water and minerals that the plant needs right up to the leaves,
through the stem and branches. The roots' drawing of water from
under the ground closely resembles a drilling technique. The ends
of the roots keep looking for water in the depths of the soil
until they find it. Water enters the root through an
external membrane and capillary cells. It then passes
through the cells to the stem tissue. From there it is transported
to every part of the plant.
This
process that the plant carries out so perfectly is, in fact, a
very complicated one. So much so that the secret of the system is
still not completely known, even in these days of space-age
technology. The existence of this sort of "pressure
tank" system was discovered in trees some 200 years ago. Yet
no law has been discovered to definitively explain how this
movement of water, against gravity, actually comes about.
All that scientists have been able to do on this subject is put
forward a number of theories about certain mechanisms. Those that
have been demonstrated in experiments are thought of as valid to
some extent. The outcome of all these scientists' efforts is the
recognition of the perfection of the pressure tank system. Such a
technology, packed into a tiny space, is just one of the proofs of
the incomparable intelligence of the designer of the system. The
water transport system in trees, and everything else in the
universe, were created by God.
The
Pressure System in Plant Roots
When
the internal pressure in root cells is lower than the external
pressure, plants take in water from the outside. Another way
of putting it is that they take water from outside only when they
need it. The most important factor establishing this is the
amount of pressure produced by the water in the roots. This
pressure has to be balanced with that outside. For this to happen,
the plant needs to take in water from the outside when the amount
of internal pressure falls. When the opposite happens, when the
inside pressure is higher than the outside, the plant gives off
water from inside itself by means of its leaves to re-establish
the balance.
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If the level of the water in the soil were slightly higher than
normal, the plant would continually take in water, because the
external pressure was higher, and this would eventually damage it.
If it were a little lower, on the other hand, the plant cell could
never take in water from the outside because the external pressure
would be low. It would even have to give off water to
maintain the pressure balance. In either case the plant
would dry up and die.
Plant
roots thus contain a balance-control mechanism to enable them to
regulate the level of pressure needed at a precise moment, neither
more nor less.
How
Roots Take in Ions from the Soil
The
cells in the roots of a plant select particular ions from the soil
to use in cell reactions. Plant cells can easily take these ions
inside themselves, despite the internal concentration of some ions
in the plant being a thousand times greater than that in the soil
solution.2
Under
normal conditions, a transfer of materials will occur from an area
of higher concentration to a one of lower concentration. But as we
have seen, just the opposite takes place in the roots as they
absorb ions from the soil. For this reason the process requires
quite substantial amounts of energy.
Two
factors influence the passage of ions through the cell membrane:
the membrane's permeability and the concentration of the ions on
either side of the membrane.
Let
us examine these two factors by asking some questions about them.
What does a plant's choosing the required elements from those in
the soil actually mean? Let us first take the concept of
"requirements." A root cell has to know all the elements
in the plant, one by one, to meet its requirements. It has to
establish which of all the elements it knows are lacking in all
parts of the plant and identify them as needs. Let us ask another
question. How is an element known? If the soil is not in a pure
state, in other words if there are other elements mixed up in it,
what has to be done to distinguish one element from all the rest?
Will
it be possible for someone to tell which is which if elements such
as iron, calcium, magnesium, and phosphorus are put in front of
him all mixed up? How can he tell them apart? If he has received
training in the subject, he may be able to identify some of them.
It will be impossible for him to identify the rest, however. So
how do plants make the distinction? Or rather, how is it possible
for a plant to know elements by itself, and to find those ones
most useful for it? Is it possible that such a process should have
been carried out in the right way every time for millions of years
by chance? In order to think about all of these questions-to which
the answer is "Impossible!"-in a more detailed and
deeper way, let us examine what kind of selective property roots
possess and what happens at the time of selection.
Roots'
Selectivity
Let
us review our chemical knowledge regarding the elements and
minerals that appear in many forms in nature. Where are they
found? Which substances go into which groups? What differences are
there between them? What experiments or observations are required
to understand what each one is? Can the fastest results be arrived
at by chemical or physical methods in these experiments? If we
just look at things from the physics point of view can we make a
proper classification of these substances if they are put on a
table in front of us? Can we distinguish minerals by their color
or form?
We
could go on. And the answer to all of the above questions is more
or less the same. Unless someone is an expert in the field,
partial or inadequate knowledge left over from school or
university will not lead a person to an accurate solution. In
order to classify our knowledge of minerals, let us this time take
examples from the human body.
There
is a total of three kilograms of minerals in our bodies. Parts of
them are essential for our health, and they are all present in the
necessary quantities. For example, if we had no calcium in our
bodies, our teeth and bones would lose their hardness. If there
were no iron, oxygen could not reach our tissues, because we would
have no hemoglobin. If we had no potassium and sodium, our cells
would lose their electrical charges and we would rapidly age.
Minerals
are present in the soil in the same way as in the human body.
Their quantities, functions, and the forms in which they are found
in the soil are all different, and many living things make use of
these minerals. In plants, for instance, systems have been set up
so that they can easily take the elements they need from the soil.
All the elements have to go to different parts of the plant after
they are absorbed according to where they are needed most. They
all have different tasks.
In
order to live healthily, a plant needs such basic elements as
nitrogen, phosphorus, potassium, calcium, magnesium and sulfur.
While plants can take most of these substances directly from the
soil, the situation is different with nitrogen. Nitrogen makes up
almost 80% of the atmosphere by volume; however, it cannot be
obtained or "fixed" directly from the atmosphere by
green plants. The plants meet their nitrogen needs by absorbing
from the soil the nitrates processed by the soil bacteria.
Other
elements are also necessary for healthy development. But these are
required in quite small quantities. This group includes iron,
chlorine, copper, manganese, zinc, molybdenum, and boron.
In
addition to these 13 minerals, plants also require the three basic
building blocks of oxygen, hydrogen, and carbon, and get them from
the carbon dioxide, oxygen, and water in the atmosphere. All
plants require a total of 16 elements.
If
these elements are absorbed in too great or too small quantities,
various deficiencies arise in the plant.
For
example, excess nitrogen from the soil leads to brittle growth
especially under high temperatures and to succulent growth, while
insufficient nitrogen can lead to yellowing, red and purple
patches, reduced lateral budding and older growth.
Phosphorus deficiency causes reduced growth, browning or purpling
in foliage in some plants, thin stems, reduced lateral bud breaks,
loss of lower leaves and reduced flowering. Phosphorus is a
very important element for the growth of young plants and seed
production. In short, the existence of these ions and their
absorption from the soil in the necessary quantities are essential
for healthy plant growth.3
What
would happen if plants did not possess this ion-selection
mechanism? What would happen if plants took in all kinds of
minerals, not just the ones they need, or took in too many or too
few minerals? There is no doubt that in that event there would be
serious disruptions to the perfect balance in the world.
The
author, who writes under the pen name of Harun
Yahya,
has published many books on political, faith-related and
scientific issues. Some of the books of the author have been
translated into English, German, French, Spanish, Italian,
Portuguese, Albanian, Arabic, Polish, Russian, Bosnian,
Indonesian, Turkish, Tatar, Urdu and Malay and have been published
in the countries concerned.
www.harunyahya.com
info@harunyahya.com
1-
Milani, Bradshaw, Biological Science, A molecular Approach, D.C.Heath and Company, Toronto, p. 430.
2- Malcolm Wilkins, Plantwatching, New York, Facts on File Publications, 1988, p. 119.
3- http://ag.arizona.edu/pubs/garden/mg/botany/macronutrient.html
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