Plant Basics If you're not a microbe and you're not an animal, chances are you are a plant. There are loads of species of plants on Earth. Just as there is a system of classification for animals, there is also a system of classification for plants. Because plants adapt so well to any climate, scientists need a way to organize the hundreds of thousands of species.
What Makes a Plant? What do they all have in common? The big thing that connects plants is photosynthesis. Photosynthesis is the process that allows plants to take energy from the Sun and create sugars. Not all plants go through the process of photosynthesis. As with all of biology, there are exceptions and you may learn about plant species that are parasites. Plants also have cell walls. In the cells tutorials we explained that all cells have a membrane. Only plants have an additional cell wall made from cellulose.
Let's look at photosynthesis. Plants are able to turn sunlight into energy but not directly. Plants are actually able to store energy in some chemical bonds that can be used later. Before we get into details, we'll explain that there are two processes on Earth: Photosynthesis and Respiration. Photosynthesis stores the energy and respiration releases that energy. It all starts with the Sun. Check out the tutorial on photosynthesis.
Learning from Plants Not only do you see plants everywhere in the real world, but they are also all over the scientific world. Scientists use them for studies in genetics. A guy named Gregor Mendel used pea pods and their flowers to come up with some of the first ideas on how traits are passed from one generation of organism to another (genetics). We also use plants for food. Scientists are constantly developing new plants that are more resistant to disease and insects. Scientists also help create plants that grow faster and make more food.
Photosynthesis -
Part I: The Sun and Light
Not all of the light from the Sun makes it to the surface of the Earth. Even the light that does make it here is reflected and spread out. The little light that does make it here is enough for the plants of the world to survive and go through the process of photosynthesis. Light is actually energy, electromagnetic energy to be exact. When that energy gets to a green plant, all sorts of reactions can take place to store energy in the form of sugar molecules.
Remember we said that not all the energy from the Sun makes it to plants? Even when light gets to a plant, the plant doesn't use all of it. It actually uses only certain colors to make photosynthesis happen. Plants mostly absorb red and blue wavelengths. When you see a color, it is actually a color that the object does NOT absorb. In the case of green plants, they do not absorb light from the green range.
Part II: The Chloroplast
We already spoke about the structure of chloroplasts in the cells tutorials. We want to reinforce that photosynthesis happens in the chloroplast. Within this cell organelle is the chlorophyll that captures the light from the Sun. We'll talk about it in a bit, but the chloroplasts are working night and day with different jobs. The molecules are moved and converted in the area called the stroma.
Part III: The Molecules
Chlorophyll is the magic compound that can grab that sunlight and start the whole process. Chlorophyll is actually quite a varied compound. There are four (4) types: a, b, c, and d. Chlorophyll can also be found in many microorganisms and even some prokaryotic cells. However, as far as plants are concerned, the chlorophyll is found in the chloroplasts. The other big molecules are water (H2O), carbon dioxide (CO2), oxygen (O2) and glucose (C6H12O6). Carbon dioxide and water combine with light to create oxygen and glucose. That glucose is used in various forms by every creature on the planet. Animal cells require oxygen to survive. Animal cells need an aerobic environment (one with oxygen).
