1. What is Photosynthesis?
Photosynthesis is a process of taking inroganic material to make new organic matter through the combining of carbon dioxide and water using
solar energy. This process only occurs in green plants, blue-green algae, and certain bacteria.
Plants capture light energy and make their own food using it. The process of photosynthesis is what allows the plants to make their own food.
Photosynthesis allows the chlorophyll inside each leaf to capture energy. The captured energy is used to build carbohydrates from simple raw
materials. (water, carbon dioxide and minerals) These carbohydrates, also known as sugar, are the plants food. The plant uses some of the sugar,
but also stores some. Photosynthesis also needs the following raw materials to function: carbon, oxygen and hydrogen. Animals breath out carbon
dioxide, so this gives the plants oxygen and carbon. Plants receive the hydrogen through water. The materials enter the plant either at the roots or
2. What does a leaf need to start the process of photosynthesis?
In the spring and the summer you will notice that the leaves on trees are green. This is because photosynthesis is taking place. In order for
photosynthesis to occur, the leaf takes in certain materials that will help with the process. A plant needs to take a gas from the air called carbon
dioxide. Carbon dioxide comes from animals when they breath. Plants also need water, which they get from their roots taking it out of the ground.
The third thing that a plant needs to start photosynthesis is the light from the sun.
What occurs in the leaf during photosynthesis?
The inside of a leaf is like a small factory. It contains everything it needs to convert sunlight, carbon dioxide and water into oxygen and sugar.
Inside the leaf there is chlorophyll. This chlorophyll is what captures the sun's light. Chlorophyll is also what gives the leaves a green color. The
sunlight is converted into chemical energy which is necessary to continue the process of photosynthesis. When this chemical energy is introduced
to the carbon dioxide and the water, glucose (sugar) and oxygen are created. A very simple way to put this is:
Carbon Dioxide + Water + Chlorophyll and Sunlight = Oxygen + Sugar
There are different parts of the leaf that make this process possible. There are stomata, which are pores on the underside of leaves. These pores let
air enter the leaf and then at night the pores release oxygen and they allow for water to evaporate. The chlorophyll is what gives the plants their
green color. Chlorophyll is found in the cells of the plants inside chloroplasts. A chloroplast is like a home for chlorophyll.
3. Why do leaves change colors in the fall?
Once the season of fall starts, you will notice a change in the color of the leaves. The leaves no longer stay green, but turn red, brown, orange,
yellow, just to name a few. There is a reason for this. During the fall there isn't enough sunlight or water for photosynthesis to take place. The
green chlorophyll disappears because there isn't the sunlight to convert to chemical energy. This allows for the bright colors that have been hidden
all summer by the green color to show through.
Just so you know, the red color in a leaf occurs because there is food, carbohydrates, trapped in the leaf. The leaf that has a brown color has waste