Photosynthesis

Organisms can be classified based on how they obtain energy. There are autotrophs, organisms that manufacture their own energy, and heterotrophs, organisms that can't make their own energy. Animals, like humans, can't obtain their energy on their own, so they eat autotrpohs or heterotrophs that eat autotrophs. Confusing? Yeah, a little. Think of it like this, we eat steak, which comes from cows. But cows don't eat other cows, they eat grass. Grass is an autotroph, thus the food chain cycle is shown. But, how does a plant like grass obtain its energy? Plants get their energy through a process called photosynthesis. Photosynthesis involves a complex series of chemical reactions, even using a by product of a previous reaction. A plant releases oxygen as a byproduct in an early reaction, but need it in a later one. Back on topic, photosynthesis uses light as its fuel. A plant absorbs sunlight through chloroplasts. The light reactions take place in the thylakoids. To clear things up, the chloroplasts have a membrane surrounding three things. These are the thylakoids, grana and stroma. Thylakoids stack to form a grana, and is surrounded by a solution called the stroma. Moving on, plants are often picky with the light they absorb. As you probably know, the visible light spectrum includes red, orange, yellow, green, blue, indigo and violet. But, why are plants green most of the time? A part of the chloroplast is the chlorophyll. There are several types , but the two important ones are chlorophyll a and chlorophyll b. These are pigments, basically a compound that absorbs light. Chlorophyll a absorbs red to yellow light in the color spectrum, while chlorophyll b absorbs blue to violet light. This is why plants typically appear green. This is only the first stage in the entire process, but I'll get to electron transfer, chemiosmosis, and the different photo systems in my next post.