1. How does a plant gain mass?
What does a plant need to grow?
Where in a plant cell does it make food?
What is the name of the process that provides a plant with food?

2. PHOTOSYNTHESIS

3. Overview: The Process That Feeds All Living Things
Photosynthesis (photo = light, synthesis = to make, put together)
Overall Definition: the process that converts solar energy (photons) into chemical energy (glucose)
Glucose

4. Remember Producers? Plants are autotrophs
They are the producers of ecosystems
Plants use energy from the sun to produce the food that feeds the ecosystem
Some bacteria (ex. blue-green algae) and some protists are also photosynthetic

5. Chemosynthesis
Certain types of bacteria and fungi use energy from INORGANIC COMPOUNDS (such as hydrogen sulfide) instead of light energy to produce food.
This process is called CHEMO-SYNTHESIS.
A comparison of photosynthesis and chemosynthesis.

6. Photosynthesis Occurs Within the Cells of Plant Leaves
Leaf anatomy
Stoma (plural = stomata)
Cuticle
Upper
epidermis
Bundle-
sheath
cell
Palisade
mesophyll
Spongy
mesophyll
Xylem
Phloem
Vein
Guard
cells
Lower
epidermis

7. Transportation Of Needed Materials
Nutrients and water, can get into and out of leaves:
Xylem: Carries water and dissolved minerals upward from roots into the stems and leaves
Phloem: Transports organic nutrients (ex. sugars) from where they are made to where they are needed
Stoma (singular): allows CO2, O2, and H2O (transpiration) to enter and leave the leaves

8. Photosynthesis converts light energy to the chemical energy of food
The leaves of plants are the major sites of photosynthesis
Leaf cross section
Mesophyll
Vein
Stomata
CO2 O2

9. Chloroplasts: The Sites of Photosynthesis
What type of cells have chloroplasts? Think back to our CELL unit
Cell Walls
Chloroplasts

10. Chloroplasts: The Site of Photosynthesis
Are the organelles in which photosynthesis occurs
Contain thylakoids, grana, and stroma
Chloroplast
1 µm
Outer
membrane
Granum
Stroma
Thylakoid
Inner
membrane

11. Structures of the Chloroplast
Thylakoid = disk-shaped sac in the stroma of a chloroplast
Grana = layers or stacks of thylakoids
Stroma = the thick fluid contained in the inner membrane of a chloroplast; made of water and enzymes

12. Chlorophyll: The Green Pigment Inside Chloroplasts
Chlorophyll is a pigment.
A pigment is any substance that absorbs light.
The color of the pigment comes from the colors of light reflected (in other words, those not absorbed).
Chlorophyll is green because it reflects green light.

13. The Chemical Reaction of Photosynthesis
Photosynthesis is summarized by the following chemical reaction: + + + +
Light
Energy
CO2
Carbon
Dioxide
H2O
Water
C6H12O6
Carbohydrate
Monomer??? O2
Oxygen
H2O
Water
(Glucose)
The Balanced Chemical Equation: 6
__CO2 + __H2O + Light Energy  C6H12O6 + __O2 + __H2O 12 6 6

14. Tracking The Atoms Through Photosynthesis
Chloroplasts split carbon dioxide and water
To make sugar molecules, oxygen, and water
Reactants:
6 CO2
12 H2O +
Products:
C6H12O6
6 H2O +
6 O2 +
The oxygen we breath comes from H2O
The carbon in our food, comes from CO2

15. Adenosine Triphosphate
ATP is the main energy source for cell processes
Energy is released when ATP is converted to ADP (Adenosine Diphosphate
Tri = Di= 2
ADP can be converted into ATP again
using energy from food to reform bonds.
ATP is made of three components
Adenine
Ribose
Triphosphate tail

16. The Two Stages of Photosynthesis
Photosynthesis consists of two processes
The light (dependent) reactions
The dark (light-independent) reactions; also called the Calvin cycle

17. The Light Reactions Occur in the grana Split water Release oxygen
Produces ATP (energy)
Produces NADPH (carries H from the light reactions to the Calvin cycle)
Light
Reflected
Light
Chloroplast
Granum
Absorbed
light
Transmitted
Light

18. The Calvin Cycle Occurs in the stroma Forms sugar from carbon dioxide
Uses ATP for energy
Also uses NADPH
Light
Reflected
Chloroplast
Absorbed
light
Granum
Transmitted
Stroma

19. Putting The Two Stages Together
The Light Reactions & The Calvin Cycle
H2O
CO2
Light
NADP 
ADP
+ P
LIGHT REACTIONS
CALVIN
CYCLE
NADPH
ATP
Chloroplast
C6H12O6
(sugar) O2

20. Summary Of Photosynthesis
The overall chemical equation: 6
__CO2 + __H2O + Light Energy  C6H12O6 + __O2 + __H2O 12 6 6

21. A More Detailed Summary
Light Reactions
Calvin Cycle
Takes place in the….
Reactants are….
Products are….
Grana
Stroma
Sunlight & H2O
CO2 , ATP & NADPH
ATP & NADPH
C6H12O6
+O2
Leaves the leaf via the stomata

22. The Nature of Sunlight
Light reactions convert solar energy to the chemical energy stored in the bonds of glucose molecules.
Sunlight is a form of electromagnetic energy, which travels in waves
A wavelength is the distance between the crests of waves
Wavelengths determine the type of electromagnetic energy
With visible light, the wavelength determines the color of the light

23. The Electromagnetic Spectrum
Is the entire range of electromagnetic energy (also called electromagnetic radiation)
Gamma
rays
X-rays UV
Infrared
Micro-
waves
Radio
10–5 nm
10–3 nm
1 nm
103 nm
106 nm
1 m
103 m
380
450
500
550
600
650
700
750 nm
Visible light
Shorter wavelength
Higher energy
Longer wavelength
Lower energy

24. The Electromagnetic Spectrum
The visible light spectrum
Includes the colors of light we can see
Includes the wavelengths (colors of light) that power photosynthesis
Pigments
Are substances that absorb visible light AND Reflect light, which include the colors we see
Chlorophyll is the most abundant pigment in plants

25. What is White Light?
White light contains all the colors of the visible light spectrum.
White light is separated into the different colors (=wavelengths) of light by passing it through a prism.
Colors of visible light spectrum = red, orange, yellow, green blue, indigo, violet (ROY G. BIV)

26. Let’s Talk About The Color Of Things….
In fictional stories, have you ever heard of anything that was invisible?
Harry Potter’s invisibility shield
The invisible man
In terms of light, what does it mean to be invisible?
All light passes through invisible objects; none is reflected or absorbed.
Why do leaves appear green?
Green light is being reflected by the chlorophyll back to your eyes and the other colors are being absorbed.

27. What Colors Of Light Are Used By A Plant?
Reflected light includes the colors we see
Absorbed light is used in photosynthesis
Light
Reflected
Chloroplast
Transmitted
Absorbed
light

28. What Colors Of Light Are Used By A Plant?
The absorption spectra of chloroplast pigments
Provide clues to the relative effectiveness of different wavelengths for driving photosynthesis

29. What Colors Of Light Are Used By A Plant?
What colors does Chlorophyll a absorb? Are these long or short wavelengths?
violet blue green yellow orange red
Absorption
Short wave
Long wave
(more energy)
(less energy)

30. The Absorption Spectra
The three curves show the wavelengths of light best absorbed by three types of chloroplast pigments.
Green has the least absorption and the most reflection making plants appear green
Three different experiments helped reveal which wavelengths of light are photosynthetically important. The results are shown below.
EXPERIMENT
RESULTS
Absorption of light by
chloroplast pigments
Chlorophyll a
Wavelength of light (nm)
Chlorophyll b
Carotenoids

31. Question 1
What is the primary difference in the ways that plants and animals obtain energy?
Answer
All living organisms need energy. Plants can trap light energy in sunlight and store it for later use in the process of PHOTOSYNTHESIS. Animals cannot trap energy from sunlight and must eat plants that contain stored energy.

32. Question 2 A. AMP B. ADP C. ATP D. ACP
Energy is temporarily stored in molecules of ATP. When a phosphate group is removed from ATP by hydrolysis, energy is released. The resulting molecule of adenosine with TWO phosphate groups bonded to it is ______.
A. AMP
B. ADP
C. ATP
D. ACP

33. Adenosine triphosphate (ATP) Adenosine diphosphate (ADP)
The answer is B. ADP is adenosine diphosphate.
The addition and release of a phosphate group on adenosine diphosphate creates a cycle of ATP formation and breakdown. The change from a less stable molecule (ATP) to a more stable molecule (ADP) releases energy needed for cellular activities. P P P
Adenosine
Adenosine triphosphate (ATP) P P
Adenosine diphosphate (ADP) P P
Adenosine

34. Question 3 A. Calvin cycle B. The Cell Cycle C. The Light Reactions
In which stage of photosynthesis is carbon from CO2 used to form a six-carbon sugar (glucose)?
A. Calvin cycle
B. The Cell Cycle
C. The Light Reactions
D. Mitosis

35. The answer is A. Light Chloroplast LIGHT REACTIONS CALVIN CYCLE H2O O2
CO2
Light
NADP 
ADP
+ P
LIGHT REACTIONS
CALVIN
CYCLE
NADPH
ATP
Chloroplast
C6H12O6
(sugar) O2

36. Question 4
What component of thylakoid membranes absorbs specific wavelengths of sunlight?
A. electrons
B. pigments
C. chloroplasts
D. mitochondria

37. The answer is B. Pigments are arranged within the thylakoid membranes; the most common pigment is chlorophyll.

38. Question 5
What is the equation for the process of photosynthesis?

39. 6CO2 + 6H2O + Light Energy  C6H12O6 + 6O2
The answer is:
6CO2 + 12H2O + Light Energy  C6H12O6 + 6O2 + 6H2O OR
6CO2 + 6H2O + Light Energy  C6H12O6 + 6O2