hi in this lesson will be talking about ecosystems which are made up of community of organisms and their environment. Now the biosphere is the sum of all ecosystems on earth. And when we look at ecosystems, we want to be thinking about energy and matter. Now the law of conservation of Energy says that energy cannot be created or destroyed. It can Onley be transferred and transformed, so energy will be transferred from the sun to photosynthetic organisms. And energy is very inefficiently transferred between organisms in an ecosystem. So most energy that moves through the ecosystem is gonna be lost is heat on. The main thing to bear in mind about energy in ecosystems is that energy is always moving through ecosystems. It doesn't stay in ecosystems. They need a constant influx of energy to keep them powered. Now matter, on the other hand, behaves differently. Conservation of matter says that matter cannot be created or destroyed and will remain constant in a closed system, meaning assuming, for example, that no matter can escape the earth, which obviously isn't true. Um, but let's just pretend that Earth is a closed system. That basically means that all of the matter that is taking part in this closed system will stay in this close system and none of it will be destroyed. It's just going to be moved around basically. So again. The main point is that energy flows through ecosystems and is continuously lost, whereas matter is recycled through ecosystems like you see here in the carbon cycle, where the carbon will be moved between various sources and we'll take a closer look at this in a little bit. But for now, let's turn the page.