Water and Life (Biology)
Click on the thumbnail to
enlarge. Depending on age
and body size, the human body
is usually made of 58%-78%
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Water is essential to life. In all life forms, including you, it's used both
as a solvent (it can dissolve things, such as body waste) and in many
metabolic processes. This means that water is used in the chemical
processes in your body. Metabolism is divided into two parts:
anabolism and catabolism.
Water is removed from molecules (molecules are a stable group of two
or more atoms) in anabolism to make larger molecules such as
starches or proteins for storage. In catabolism water is used as a solvent
to break apart molecules and make smaller ones such as glucose,
amino acids, and other things.
Photosynthetic plant cells use water as well. Water is made up of two
hydrogen atoms and one oxygen atom (more information about this is
on the chemistry page). Photosynthetic cells in plants use energy from
the Sun to separate the hydrogen atoms from the oxygen atom. The
hydrogen is combined with carbon dioxide (CO2) to form glucose (a
type of sugar - "plant food") and the plant releases oxygen "waste" that
we breathe. This is why it's important to water your plants!
Depending on your age and body size, the human body is usually 55%
- 78% water. Depending on daily activity, temperature, etc., your body
needs between one and seven litres of water a day! The
recommended amount is 1-2 litres, or about 7-8 cups of water every
day. (Keep in mind that water is often found is some foods and drinks).
If you were to collect a drop of water from a stream and view it under a
microscope, you would probably discover many tiny organisms in it.
Water supports many life forms, from microscopic organisms to large
marine mammals such as whales and dolphins. Most fish spend their
entire lives in water and amphibians live parts of their lives in water. As
it was said, water is essential to life.
To learn more about water and its effects on life, please visit the links
page for a list of websites where you can find more information on this
subject and others related to water.