2. CHAPTER 8 Photosynthesis:
chloroplast
leaf cell
leaf
CHAPTER 8 Photosynthesis:

3. Key Concept Questions:
Where do plants get the energy they need to produce food?
What is the role of ATP in cellular activities?
What is the overall equation for photosynthesis?
What is the role of light and chlorophyll in photosynthesis?
What is the function of stomates and guard cells?

4. http://www. pearsonsuccessnet. com/snpapp/learn/navigateIDP. do

5. Energy needs of life All life needs a constant input of energy
Animals = Heterotrophs
get their energy from “eating others”
eat food = other organisms = organic molecules
make energy through respiration

6. Plants = Autotrophs
get their energy from “self”
get their energy from sunlight
build organic molecules (food) from CO2
make energy through photosynthesis

7. + water + energy  glucose + oxygen
Photosynthesis
+ water + energy  glucose + oxygen
carbon
dioxide
6CO2
6H2O
C6H12O6
6O2
light
energy  +
This is the equation you should get used to seeing, but this is not the whole story…

8. ATP
What is the main chemical fuel that most living organisms use to store energy?
ATP – adenosine triphosphate
What does an ATP molecule consist of?
Adenine, ribose, and three phosphate groups
What do the lines between the parts of the molecule represent?
Chemical bonds

9. WHAT IS THE ROLE OF ATP IN CELLULAR ACTIVITIES?
The characteristics of ATP make it an exceptionally useful molecule that is used by all types of cells as their basic energy source

10. Even though ATP is very efficient at transferring energy, it is not very good for storing energy over the long term.
Living organisms store large amounts of energy in the form of glucose (90 times more energy than ATP)
Cells can break apart glucose and make ATP molecules very easily to release the energy slowly

11. How do plants live? Photosynthesis Energy building reactions
collect sun energy
use CO2 as carbon for new sugars
glucose, cellulose, starch
build all other organic molecules
proteins, lipids, carbohydrates, DNA
store energy for future use or to be eaten
starch in seeds & roots

12. Chloroplasts absorb sunlight & CO2 Leaf Leaf Chloroplasts Chloroplasts
contain
Chlorophyll
Chloroplast
make energy & sugar

13. Putting it all together
CO2
H2O
C6H12O6 O2
light
energy  +
H2O
CO2
Plants make both:
ATP
sugars
sunlight
ADP
Energy Building
Reactions
Sugar Building
Reactions
ATP
sugars
C6H12O6 O2

14. WHAT IS THE ROLE OF CHLOROPHYLL IN PHOTOSYNTHESIS?
In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule in chloroplasts
Sunlight, which your eyes perceive as “white” light, is actually a mixture of different wavelengths of light of various colors

15. HOW WELL WOULD A PLANT GROW UNDER PURE YELLOW LIGHT?
Any compound that absorbs light also absorbs energy from that light. When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons. These high-energy electrons make photosynthesis work
HOW WELL WOULD A PLANT GROW UNDER PURE YELLOW LIGHT?
The plant would not grow well because neither chlorophyll a nor b absorbs much light in the yellow region of visible light

16. Factors that can affect photosynthesis
water
temperature
intensity of light

17. So what does a plant need?
Bring In
CO2
H2O
light
Let Out O2
Move Around
sugars
leaves
shoot
roots
6CO2
6H2O
C6H12O6
6O2
light
energy  +

18. Leaf Structure xylem (water) phloem (sugar) cuticle epidermis
palisades
layer
spongy
layer O2
H2O
CO2
stomate
guard cell
gases in & out
water out
transpiration O2
H2O
CO2

19. Stomates guard cell stomate Function of stomates CO2 in O2 out H2O out
Prevents dehydration
guard cell
stomate

21. Xylem
carry water up from roots

22. Phloem: food-conducting cells
carry sugars around the plant wherever they are needed
new leaves
fruit
seeds

23. Putting it all together
Making a living…
sunlight
leaves = solar collectors
photosynthesis
gases: CO2 in & O2 out
stomates = gases in & out
H2O
roots take in water from soil
pulled up by leaf evaporation
nutrients
roots take in from soil

24. How are they connected? Respiration  Photosynthesis 
glucose + oxygen  carbon + water + energy
dioxide
C6H12O6
6O2
6CO2
6H2O
ATP  +
Photosynthesis
So, in effect, photosynthesis is respiration run backwards powered by light.
Cellular Respiration
oxidize C6H12O6  CO2 & produce H2O
fall of electrons downhill to O2
exergonic
Photosynthesis
reduce CO2  C6H12O6 & produce O2
boost electrons uphill by splitting H2O
endergonic
+ water + energy  glucose + oxygen
carbon
dioxide
6CO2
6H2O
C6H12O6
6O2
light
energy  +

25. The Great Circle of Life!
sun
Energy cycle
Photosynthesis
plants
H2O
CO2
glucose O2
animals, plants
Cellular Respiration
The Great Circle of Life!
Where’s Mufasa?
ATP

26. Key Concept Questions:
Where do plants get the energy they need to produce food?
Sunlight
What is the role of ATP in cellular activities?
It is used by all types of cells as their basic energy source
What is the overall equation for photosynthesis?
6CO2
6H2O
C6H12O6
6O2
light
energy  +

27. Key Concept Questions:
What is the role of light and chlorophyll in photosynthesis?
Chlorophyll absorbs light and this energy is used to drive photosynthesis
What is the function of stomates and guard cells?
Guard cells control the size of the stomate.
Stomates allow CO2 to enter the leaf and H2O and O2 to leave the leaf