Flow of Energy

Let’s think for a little bit on how energy flow and how matter is recycled in an ecosystem. Let’s first consider energy. Energy for most ecosystems originally comes from the sun. There are other sources of energy like moonlight, but even that essentially comes from the sun, there’s also geothermal energy. Now how does the ecosystem make use of the energy that is supplied from the sun? how does it get sored into the ecosystem, especially as biomass? Well, it starts with primary producers, which will often be plants, but sometimes they can also be bacteria that is able to photosynthesize or take that energy and produce biomolecules that store energy from it. Plants as primary producers, are sometimes referred to as autotrophs, as they get their own food from the sun. Now if you were to zoom into the molecules into this plant, and this is a huge oversimplification, you will see all these bonds between these carbons, and to make those bonds energy is required, now these bonds were to be broken, energy would be released. Where do these carbon molecules come from? They come from the air, and the whole process of photosynthesis is all about fixing that carbon, from a gaseous form into the structure of a plant. Now this is not a perfectly efficient process, as not all of the energy from the sun is going to be stored, some of it is reflected. Some of it is even used by the plant, eventually though, some of the energy is released as heat.

Cycle In The Ecosystem

In thermodynamic systems you’ll find this trend a lot. This is just the beginning of our energy flow, now let’s see how that energy flow to the other parts of the ecosystem. Now the next phase, would have characters that would eat the plants. Note that this system is very simple and the real ecosystems are exponentially complex compared to it, this is only done for ease of explanation. Now the folks that eat the primary producers are called primary consumers. So, we’ll take a bunny and a squirrel, they feed through the primary producers. Now why do these primary consumers eat the primary producer? It is to get the energy from those bonds in the biological molecules, from those carbon and other bonds. It’s able to use this energy to grow itself, run around, reproduce, etc. Now it also stores some energy in its own biomass. Now again, this process is not very efficient, as only 10% of energy is transferred ever time it’s going through a trophic.

Now, we know that in many ecosystems there are things that like to eat rabbits and squirrels. In our example we’ll just take a fox. This fox hence would be a secondary consumer as it eats primary consumers. Now we can continue this cycle is we take any species next in line that consume foxes. This species, let’s say human, eats the fox and takes some of the energy and the matter from the fox to grow and live himself. This consumer would be called a tertiary consumer. Now if there is no one left to eat the human, then he would be considered an apex consumer or an apex predator, they are on the top of the food chain. Now at some point, all of our characters, the bunny, the fox, squirrel, human, all of them die and then their energy is going to used by decomposers. The decomposers can take the energy from the dead carcass of these beings, and they can make use of it, to live and reproduce, and then they can release a lot of those nutrients, the energy, the recycled matter, once again to be used by the plants.

Transfer Of Matter

Let’s discuss a little about matter, now matter is recycled, and in the example that we have set up, no matter is going to leave the ecosystem or be magically created or destroyed. Now when you see a leaf or a blade of grass growing, that matter didn’t just appear out of nowhere, the matter was always there in the form of carbon dioxide. The plant is just using the energy from the sun to fix that carbon from a gaseous form into a solid form, and it is able use that energy to make bonds between the carbons and these biological molecules that store energy. The whole ecosystem then uses that energy. The oxygen released by the trees are used by the animals to metabolize these biological molecules. Now when these animals use the biological molecules that they get from consuming, they break those bonds through respiration, then that carbon gets released from the animals in the form of carbon dioxide. As you can see energy is flowing the whole time, all the matter and energy in our body has always been there, it just keeps being recycled. After the animals in the eco system die, their energy and matter goes back to being plants, and the process is started all over again.


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