1. Photosynthesis
Chapter 6

2. Photosynthesis Makes Food Energy
Energy- ability to do work or cause change
Two Types of energy acquirement
Autotroph
Heterotroph

3. Autotrophs Organism that can make it’s own food
Examples- plants, algae, some bacteria

4. Heterotrophs Organism that must consume others to obtain energy
Example- humans, deer, birds

5. Food Chain Sun is the ultimate source of energy on Earth
Sun provides energy for autotrophs
Autotrophs become food for others

6. Energy Molecule
ATP (Adenosine TriPhosphate) is the body’s main energy source
Structure- 3 phosphate groups
Like a fully charge battery

7. How energy is released One phosphate group is broken off
Left with ADP (adenosine diphosphate)
Breaking the bond releases energy
Exergonic reaction

8. Visible Light Spectrum
Visible Light- array of colors ranging from red to violet
Each color has unique wavelength

9. Colors we see are actually a reflection
White- all colors reflected
Red- red reflected
Black- absence of color

10. How Does Light Get Absorbed?
Pigments- compound that absorbs light
Plants have pigments found in leaves
Chlorophyll- most abundant pigment found in plants
Chlorophyll a- absorbs red
Chlorophyll b- absorbs blue
Result= green being reflected

11. Light Reflection

12. Involvement with Photosynthesis
Chlorophyll a- directly involved
Light energy is absorbed by this pigment

13. Other pigments Accessory pigments- assist in capturing light energy
Carotene- Orange
Xanthophyll- yellow

14. Where Photosynthesis takes Place
Chloroplasts- double membrane organelle that has chlorophyll inside

15. Chloroplast Specialized organelle found in plant cells only
Seen in Elodea from cell lab

16. Parts of a Chloroplasts
Thylakoid- system of flattened membranes
Grana/Granum- cluster of thylakoids stacked on each other
* Picture stack of green pancakes

17. 3. Photosystem- found in membrane of thylakoid
~ group of pigment and proteins
~ gives green color

18. 4. Stroma- fluid that fills the chloroplast

19. What is Photosynthesis?
The process of converting sunlight into food molecules
Occurs in two steps
Light Reactions
Calvin Cycle

20. Overall Reaction
6 Carbon dioxide + 6 water + sunlight = glucose + 6 oxygen
6 CO2+ 6 H2O + light = C6H12O6 + 6 O2

21. Light Reactions Location- thylakoid membrane
Starts with- light and water
Ends with- oxygen, ATP and NADPH (another energy molecule)
(nicotinamide adenine dinucleotide phosphate-oxidase

22. What Happens Light hits photosystem I and II
Chlorophyll electrons become excited
Electrons enter Electron Transport Chain- group of proteins in membrane
NADPH is produced
ATP is produced
~Chemiosmosis- process of making ATP

24. End Result of Light Reaction
Water- source of electrons for photosystems, H+ and produces oxygen
Electrons- 2 e- end up combining with H+ and NADP+ to make NADPH
ATP- is made from light energy to add phosphate to ADP creating ATP

25. The Calvin Cycle AKA- Dark Reaction, Light-Independent
Location- Stroma
Starts with- Carbon dioxide, ATP, NADPH
Ends with- Glucose

26. Carbon Fixation
Changing of Carbon Dioxide gas into an organic compound
Occurs in several steps (Biochemical Pathway)
Biochemical Pathway- series of related reactions where product of one step becomes reactant of next step

27. Example Biochemical Pathway
Overall reaction is A D
Steps are
A B
B C
C D

28. Steps of Calvin Cycle One Carbon dioxide is added at a time
Cycle repeats 6 times to make one glucose molecule
~ ATP and NADPH are used as energy source for the reactions

29. How Plants Get CO2
Stomata- opening on underside of leaf (like a mouth)
Plants can control opening and closing
CO2 comes in
Water and O2 are released

30. Stomata

31. Alternate Pathways Used in hot, dry environment to conserve water
C4 Pathway- creates 4 Carbon molecule
CAM Pathway- stomata opens at night instead of the day
Seen in desert plants

32. Effects on Rate of Photosynthesis
Temperature- too cold or too hot will slow down the rate
Light intensity- more sunlight will increase the rate till it reaches max level
Amount of water