The Story of my Carbon

Carbon is not alive. But without carbon, there would be no life at all.

This story can also be read on Medium.

A few weeks ago, we featured the life story of a carbon atom.  Somewhere there, Carbon noted that you can’t really call an atom  “alive”. But, be that as it may, life and carbon do have a connection.

The  atom of carbon has 6 protons. It is common on Earth, and is an  essential component of several materials such as graphite and diamond.  But, more importantly, carbon is the main component of all living  things.

Plants are eating carbon everyday. They open their thousands of tiny mouths and swallow it.

Tiny  mouths? Yes — plants have many microscopic holes on their leaves, which  they can open or close depending on the light and drought in their  area. These holes are called “stomata” (but who cares about this evil  scientific name?). Of course, these holes are much smaller than what is  shown in the picture.

When  plants swallow carbon, it comes in the form of “carbon dioxide”. The  carbon is joined together with two atoms of oxygen, and the three  together form one single molecule of gas. Many of them together go to  form part of the air we breathe — which is, of course, the air that  plants breathe too.

When  plants swallow carbon in the form of carbon-dioxide, it enters what  scientist call the “Calvin cycle”, which is too complicated to go into  at the moment. What happens in the end is that the carbon is taken away,  and joined with other, different, atoms to make sugar.

The oxygen — which just broke up with the carbon — goes sadly away to breathe and find a new partner.

Plants  love sugar. (I do, too!). In plants, sugar is stocked in places like  roots, where it’s embedded into “starch”, or in the fruits, where it’s  stored as “fructose”. Fructose is a small sugar. Glucose is another one.  Starch, on the other hand, is a giant, long sugar. Cut starch in small  pieces and you will get glucose.

A plant has different organs: leaf, root, stem, flower, fruit. Along its life, a plant has different needs for each organ.

In  spring, for example, the plant needs to send sugar to the shoot — the  part of the plant that’s above ground — to grow a flower and then a  fruit. In the winter, on the other hand, plants send sugar down to the  root to store it. The way plants allocate sugar — that is, decide how  much the shoots or roots get — is well studied by scientists.

Many  factors change the way organs compete to get their share of the sugar.  It can depend on many things, including the how much light they have,  the level of water they can access, and the amount and quality of  nutrients in the soil. If the limiting factor is belowground, the plant  sends more sugar to the root. If it is aboveground it’s the shoot that  gets the sugar.

But  if you want to grow healthy plants, you don’t always have to get into  fancy soil manipulation. It might be enough to simply change the size of  your pot.

A study published in Functional Plant Biology  showed that doubling the size of the pot increases the plant growth by  43%, just because it has more nutrients available to draw upon.  Moreover, a small pot decreases the photosynthetic rate: it can’t  convert sunlight into energy as fast. So if you want a vigorous plant,  buy it a big pot (unless you want a bonsai, of course).

The  atom of carbon is now in a chain of six other carbons, in a molecule  called fructose. The fructose is a sugar mainly found in …. fruits!

Babe the pig who was wandering around, comes close to an old tree and eats its fruit. Hmm — nice apples. Babe  the pig uses carbon from the apple to build his own body. He uses it to  grow, and to maintain his body-temperature. On average, 10% of the  carbon a primary consumer like him eats is used for the animal growth or  reproduction. All the other atoms of carbon are lost while breathing,  getting together with oxygen to form carbon-dioxide again.

I was wandering around the meadow, and, when I saw Babe the cute pig, I thought of all the ham I could eat. Hmm — nice ham. I took my butcher knife, killed Babe the pig and cut a large slice of ham. Hmm — nice fat.

Meat  is full of fat, and fat is full of carbon. In fact, a fatty acid — the  “fat molecule” — is made of a chain of carbon. The fatty acid’s name  depends on the number of carbons in the chain. The secondary consumers —  like me — use only 10% of the carbon from the primary consumer — Babe —  to grow (big, as well as fat!) and make babies. All the rest is  breathed away.

That  means secondary consumers only uses 1% of the carbon from the producer —  the apple — to grow and make babies. All the rest gets lost along the  way. That, by the way, explains why it’s more efficient to be  vegetarian.

When  I die, my body will be decomposed by cute bacteria and decomposers,  which will feast on my fat corpse. I will joyfully participate in the  organic fertilization of the meadow, where my good friend the apple tree  will grab soil nutrients with its roots.

It feels so nice to be part of such a cycle.

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