3.1 PHOTOSYNTHESIS

8.3.1 Photosynthesis

Plan and conduct an investigation and use the evidence to construct an explanation of how photosynthetic organisms use energy to transform matter.
Emphasize molecular and energy transformations during photosynthesis. (PS3.D,LS1.C)

In this section, focus on matter and energy. Within a natural system, the transfer of energy drives the motion and/or cycling of matter.

What will I learn: 

I will learn that plants transform light energy and into chemical energy by a process called photosynthesis

Why I will learn it:

I will learn it so I can describe the process of photosynthesis, which is the foundation of all life on earth

How I will know I have learned it:

When I can describe photosynthesis and the products of photosynthesis.  

EXPLORE THIS PHENOMENON

Video of lima bean growth from seed http://go.uen.org/aZ2

1. What do you already know about how plants grow?

2. Using your prior knowledge, identify what plants need in order to grow?

3. What questions do you have about how plants grow? 

Photosynthesis Reactions: Food from Light

Most of the energy used by living things comes either directly or indirectly from the sun. That is because sunlight provides the energy for photosynthesis. Photosynthesis- is the process by which plants and other organisms, including some types of bacteria, make a sugar called glucose (C6H12O6). Photosynthesis uses carbon dioxide and water to produce oxygen and glucose. The overall chemical equation for photosynthesis is: 

Photosynthesis changes light energy from the sun into chemical energy that is stored by the plant in the form of glucose molecules. Glucose is then used for energy by the cells of the plant. Although organisms such as plants make their own glucose, other organisms that don’t do photosynthesis are able to get glucose for energy from the food they eat. 

A plant appears green because pigments in the leaves and stems absorb red and blue light and reflect back green light.  So the plant appears green to our eyes because it only reflects back green light.  

The two objects you see in the picture are tiny parts of a cell.  A plant has CHLOROPLASTS.  Chloroplasts have green chlorophyll pigment in them that capture the energy of the sun, and then create glucose (sugar) from CO2 and water.  An animal has a tiny part in each cell called a MITOCHONDRIA.  The mitochondria helps to break down sugar into energy in animal cells. 

Change in matter
Plants through the process of photosynthesis are able to make sugars. Most of a plant's body is made of sugars that the plant is able to put together using the materials of carbon dioxide and water. Where does the mass of a giant redwood tree come from?

Photosynthetic Organisms
The organisms pictured below are photosynthetic organisms because they all use sunlight to make glucose. In addition to plants organisms that do photosynthesis also include some types of bacteria and algae. 

  A large amount of photosynthesis takes place in the plants of this lush  tropical rain forest. 

The green streaks in this lake are photosynthetic bacteria. 

The green "scum" on this pond consists of photosynthetic algae

Putting It Together

1. Explain how your understanding of plant growth and photosynthesis has
changed.

2. Think of another phenomenon that deals with photosynthesis.

3. Explain what is going on with plant growth based on what you have learned in
this section.