1. Ecosystem Recycling
Chapter 9
Section 9.2 and 9.3

2. The Carbon Cycle
Carbon is cycled through ecosystems mainly through the processes of photosynthesis and cell respiration.
Photosynthesis – converting light energy into chemical energy stored in organic compounds (carbohydrates)
Formula: 6 CO2 + 6 H2O + sun C6H12O6 + 6 O2
(energy) (glucose)
*Autotrophs (producers) carry out photosynthesis to make food
Cellular Respiration- process of cells making energy (ATP) by breaking down organic compounds
Formula: C6H12O6 + 6 O CO2 + 6 H2O + ATP
(Glucose) (energy)
*Heterotrophs (consumers) AND autotrophs (producers) use cell respiration to get energy from food
What do you notice about the equations for these two processes???
**** The products of one are the reactants for the other

3. Photosynthesis to Respiration
Heterotrophs eat other organisms, and autotrophs use the process of photosynthesis to create their own food.
Once heterotrophs eat food, or autotrophs make food, cellular respiration takes place to break down food molecules and release energy in the form of ATP.
ATP (adenosine triphosphate) – chemical compound used by cells to store and release energy
Cellular respiration provides the ATP that all cells need to support the activities of life.

5. Photosynthesis takes place in the chloroplast The Structure of the Chloroplast:
Double outer membrane
Thylakoids- inner
membranes arranged as
flattened sacs
Grana- stacks of thylakoids
Stroma- liquid solution
surrounding grana

6. Overview of Photosynthesis
“Photo” = light “Synthesis” = to make
Photosynthesis is a process which makes organic compounds (sugars) using sunlight
Converts solar energy into chemical energy (energy stored in bonds of chemical compounds)
There are 2 main steps to photosynthesis:
Light-Dependent (Light) Reactions
Light-Independent (Dark) Reactions
Animation

7. Light Reactions Converts solar energy into energy used for the
dark reactions.
Requires the absorption of sunlight and water.
Pigments like chlorophyll aid in the absorption of sunlight.
Takes place in the thylakoid membranes of the chloroplast.
Products include ATP and a molecule called NADPH.
Serve as an energy source for the next step of the process.
Oxygen is also produced as a by-product.
Much of the oxygen is given off to the atmosphere.

8. Light Independent Reactions (calvin cycle)
Takes carbon from CO2 and puts it into organic compounds (process called carbon fixation).
Requires CO2 from the atmosphere and ATP and NADPH as energy sources.
ATP and NADPH are produced during the light reactions.
Takes place in the stroma of the chloroplast.
Produces glucose and other organic compounds.
Broken down and used for energy.
Stored for future energy needs.

9. Factors Affecting Photosynthesis
Amount of water
Shortage of water can slow or even stop photosynthesis
Plants in dry climates have waxy coating on leaves to prevent water loss.
Temperature
Enzymes of photosynthesis function best around 35°C.
Temperatures above and below this range can slow photosynthesis.
Intensity of Light
Increase in light intensity increases rate of photosynthesis.
At some point, plant reaches its maximum rate and cannot go any faster, no matter how much light is added.

10. Cellular Respiration C6H12O6 + 6 O2. 6 CO2 + 6 H2O + energy (Glucose)
Cellular Respiration C6H12O6 + 6 O CO2 + 6 H2O + energy (Glucose) (ATP)
Cell respiration is a process which breaks down organic compounds to release energy in the form of ATP.
Both heterotrophs AND autotrophs perform cell respiration.
2 kinds of cell respiration:
Anaerobic (takes place in absence of oxygen)
Aerobic (takes place in the presence of oxygen)

11. Anaerobic Respiration
Does NOT use oxygen and takes place in the cytosol.
NOT efficient - produces only small amounts of ATP.
Used by prokaryotes or simple eukaryotes
Used by complex eukaryotes only as a backup to aerobic respiration.
2 different kinds of anaerobic respiration:
Lactic Acid Fermentation
Alcoholic Fermentation
Both produce by-products that are used by humans.

12. Anaerobic Respiration (cont ‘d.)
Lactic Acid Fermentation
Performed by bacteria.
Produces lactic acid as a by-product.
Lactic acid makes yogurt and cheese
Lactic acid is made in your muscles during strenuous exercise and can cause soreness and cramps.
Alcoholic Fermentation
Performed by yeast.
Produces ethyl alcohol and CO2 as by-products.
Bread – CO2 bubbles push the dough up and make it rise.
Makes wine and beer - Yeast breaks down the sugars in grains or grapes producing CO2 and alcohol.
Used to be used to make other carbonated beverages like root beer.

13. Aerobic Respiration takes place in the mitochondria of BOTH plants & animals
picture
Double membrane (just like chloroplast)
Matrix – inner space
Cristae – folded inner membranes
Why would you expect to have an abundance of mitochondria in your muscle cells?

14. Aerobic Respiration
Occurs in the presence of oxygen and takes place in the mitochondria.
Much more efficient process than anaerobic respiration.
Produces about 19 times more ATP than anaerobic respiration.
Used by complex eukaryotes with large energy requirements.
Carbon dioxide and water created as by-products.
2 main parts to aerobic respiration:
Krebs Cycle – happens in matrix of mitochondria
Takes the sugar and starts to break it down for the ETC
Electron Transport Chain (ETC) – happens in cristae of mitochondria
Where most ATP is produced

15. Let’s wrap it up...
Photosynthesis converts solar energy into chemical energy (autotrophs).
Respiration makes ATP by breaking down organic compounds (either consumed or made depending on whether organism is an autotroph or heterotroph).
Products of photosynthesis are the reactants of cell respiration and vice versa.
Do all organisms carry out photosynthesis?
Do all organisms carry out some sort of cellular respiration?