1. Photosynthesis and Cellular Respiration/ Limits on Energy Transfer
Chapter 2
Section 2.1-2
Photosynthesis and Cellular Respiration/ Limits on Energy Transfer

2. Water + Carbon Dioxide  Glucose + Oxygen
Photosynthesis
Food webs always begin with autotrophs, such as plants.
Plants get their energy through the process of photosynthesis.
Chlorophyll +Light
Water + Carbon Dioxide  Glucose + Oxygen
6H20(l) + 6CO2 (g)  C6H12O6 (aq) + 6O2 (g)

3. Cellular Respiration
All organisms, including plants, undergo cellular respiration in order to use the energy in their food.
Cellular respiration breaks down glucose, releasing the energy stored in its bonds.
Glucose + Oxygen  Carbon Dioxide + Water + Energy
C6H12O6 (aq) +6O2 (g)  + 6H20(l) + 6CO2 (g) + energy

4. Chemosynthesis Not all food webs begin with photosynthetic organisms.
In a few ecosystems, such as caves or deep oceans, producers carry out a process called chemosynthesis instead of photosynthesis.
Chemosynthesis – the process by which non-photosynthetic organisms convert inorganic chemicals to organic compounds with a source of energy other than solar.
Chemoautotroph – an organism that performs chemosynthesis.

5. Chemosynthesis inorganic chemicals that are used:
H2S, NH3, Fe2+, and S8
Example of Chemosynthesis equation:
This would be of a bacteria using ammonia
Ammonia + carbon dioxide + thermal energy nitrate + carbohydrate

6. Limits on Energy Transfer
Every time energy is transferred between components of an ecosystems, the amount of energy available to the next trophic level is reduced.
This is because whenever energy is transferred, some of the energy is transformed to a different form.
Some energy is released as thermal energy during cellular respiration, and some of it is converted to chemical molecules other than glucose.

7. Ex. Food Chain Spruce Tree  Deer  Wolf
Spruce Trees make their own food by photosynthesis. The plant uses most of that energy to carry out it’s life processes. Therefore, when eaten by the deer not all of the original energy is passed to the deer.
Once the deer has eaten the spruce bud most of the energy goes to digestion and is used by the deer. Some is lost through liquid and solid waste and some is released as thermal energy. Only 10% of the spruce bud is transferred to the deer.
Like the deer, the wolf loses some of the energy in its meal during digestion and body maintenance. Therefore only about 10% of the energy from the deer is transferred to the wolf.

8. The Laws of Thermodynamics
This process of losing energy is supported by the laws of thermodynamics.
The first law states that energy cannot be created or destroyed only transformed.
The second law states that during any energy transformation, some of the energy is always converted into an unusable form, most commonly thermal energy.