1. Photosynthesis Notes

2. Why Study Photosynthesis?
*All food webs start with photosynthesis!*
Photosynthesis is arguably the most important biological process on earth because of two key chemical reactions
Liberating oxygen:
Generating oxygen gas from carbon dioxide
Consuming carbon dioxide
This carbon dioxide comes from the air!

3. How does photosynthesis affect us?
Photosynthesis fulfills our food requirements
Photosynthesis fulfills our needs for fiber and building materials
Energy stored in petroleum, natural gas, and coal all came from the sun via photosynthesis
Firewood is only made with photosynthesis
Photosynthesis controls the makeup of our atmosphere (high oxygen, low carbon dioxide)

4. Photosynthesis and Food
What biological kingdom serves all of our energy needs directly or through herbivorous animals?
Plant Kingdom
What is sunlight?
Pure energy
To be beneficial:
Energy in sunlight must be converted to other forms
The process changes the energy in sunlight to kinds of energy that can be stored for later use

5. Where is photosynthesis carried out?
Photosynthetic reaction centers
Which are found in leaves
Which convert light energy to chemical energy (the form used by all living organisms)
One of the major energy harvesting processes in plants involves using the energy of sunlight to convert carbon dioxide from the air into sugars, starches, and other high-energy carbohydrates
What is released in the process? Oxygen
Later, when the plant needs food, it draws upon energy stored in these carbohydrates

6. How do we get energy from spaghetti?
This will be part of our Do-Now question tomorrow. You must do your best to explain this based on the reading and we will review tomorrow!

7. How did the absence of photosynthesis lead to the extinction of the dinosaurs?
This will be part of our Do-Now question tomorrow. You must do your best to explain this based on the reading and we will review tomorrow!

8. Photosynthesis and Energy
What makes up the bulk of dry wood and other plant material? Cellulose
Which is one of the carbohydrates resulting from photosynthesis
How does firewood lead to heat?
This will be part of our Do-Now question tomorrow. You must do your best to explain this based on the reading and we will review tomorrow!

9. Our current sources of energy
Coal
Oil
Natural Gas
All three of the above come from ancient plants and animals. The energy stored within them is chemical energy that originally came from sunlight through the process of photosynthesis
Thus all of the energy we use today was originally solar energy!

10. Photosynthesis Fiber and Materials
Besides being burned for firewood, wood is used for:
Building, making paper, cotton, wool, etc.
Paper = cellulose produced from photosynthesis
Cotton = a plant
Petroleum (oil) is needed to make plastics and synthetic (man made) fibers that make up many of the things we use. Because oil comes from once living materials, even plastics depend on energy from the sun!

11. Photosynthesis and the Environment
Why are greenhouse gases bad?
Photosynthesis converts carbon dioxide from the air to carbohydrates and other kinds of “fixed” carbon an releases oxygen to the atmosphere
Conversely, when we burn firewood, coal, oil, and other fossil fuels, oxygen is consumed, and carbon dioxide is released back to the atmosphere
So the big problem is that we are releasing carbon dioxide back to the atmosphere faster than plants are able to remove it!

12. Don’t forget to answer your assigned question!