Photosynthesis

How photosynthesis works, how trees breath

Have you ever walked through the woods and breathed in the air, thinking how fresh and clean it smelled? It isn't your imagination.

You are breathing brand new oxygen produced by the very trees surrounding you.
How does this happen?

It happens through a truly miraculous process known as photosynthesis.

what is photosynthesis?

Photosynthesis is the means by which trees and other plants turn sunlight into food.  It's a process that all green plants, as well as algae and some bacteria, use for their growth.

In a series of biochemical processes, the chlorophyll in the tree's foliage captures light energy in the form of photons and turns it into the tree’s (or other plant’s) fuel.

How Does it Work?

In the most common form of photosynthesis, the photons provide the energy needed for water and carbon dioxide (collected mainly in the tree's leaves and roots) to be transformed into other molecules. Through a series of steps the carbon dioxide and water are changed into simple sugars, with oxygen as a waste product.


The general formula looks like this:
6 CO2 + 12 H20 + photons = C6H12O6 + 6 O2

In English that is:
6 carbon dioxide molecules + 12 water molecules plus light energy leads to a glucose molecule and 6 oxygen molecules. (Doesn’t seem like much by multiply by trillions of times and it starts to add up.)

The tree then transforms the glucose (sugar) into the biochemical fuels needed to continue it's own growth. At the same time it releases excess oxygen into the air through pores in its leaves.

How photosynthesis works

what is chlorophyll?

Chlorophyll is a molecule found in green plants. In fact, it is what gives the plants that green color. This essential molecule is what allows photosynthesis to happen, by combining with other molecules to transform light and carbon dioxide into oxygen and other by-products.

what is a photon?

Without getting too deeply into quantum mechanics (!) you can think of a photon as a sort of bundle (a quanta) of light, an individual "thing" that smacks into the tree as sunlight. Just don't tell your physics friends that I described it that way, since photons don't actually have any mass.

A more sophisticated answer to the question of what a photon is can be found here.

Photosynthesis, Why Should We Care?

We should care about photosynthesis for three main reasons. Although, to be selfish about it, it all really boils down to one: we can’t live without it.

More specifically, photosynthesis plays three important roles.
watercolor by Cynthia Drinkwine
 It feeds the plant (that alone should be enough. It’s spring in Vermont, anything green is a sight for winter-tired eyes).

 It “fixes” carbon, meaning it takes carbon dioxide, which is a greenhouse gas and puts the carbon into a solid form (in the glucose or other sugar produced), thereby reducing the amount of CO2 in the air. In fact, green plants are essential in helping stabilize the environment by taking up CO2. Unfortunately, we humans are presently producing far more CO2 than plants can take up.

It releases oxygen into the air as a waste product. In essence, trees and other plants "inhale" CO2 and "exhale" oxygen, while we humans and other animals do the opposite.

This last is especially important, because without plants we wouldn’t have enough air to breath.
We literally couldn't survive without trees. The majority of the oxygen in the air comes to us through photosynthesis.

So plant a tree today and then pat yourself on the back for taking a step towards making our planet a better place. Next time you're in the woods think about all the trees "breathing" around you and remember that without them we wouldn't have the oxygen we need to breath.

How photosynthesis works

Next time you're in the woods think about all the trees "breathing" around you and remember that without them we wouldn't have the oxygen we need to breath.

misc fact:

Poison Ivy loves CO2. You may notice it growing next to the road. It uses the exhaust from the traffic to help grow to truly prodigious sizes (see bush to right).

That alone should make you think twice about the amount of excess CO2 we produce, especially here in the USA.


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