1. Anatomy, Physiology & Photosynthesis
Plants
Anatomy, Physiology & Photosynthesis

4. Plant anatomy Aerial portion Terrestrial portion absorb light energy
gas exchange of O2, CO2 & H2O
stomata (holes)
Structural support
Terrestrial portion
anchorage
H2O absorption
nutrient uptake

5. Leaf epidermal peel Leaf cross section
Stomata regulate uptake and release of gases not by pressure but by simple diffusion.
In order to exchange gases stomata must remain open and lose large amounts of water.
Is this a good strategy?
Leaf cross section

6. Cohesion and adhesion of water!
Water moves due to a concentration gradient and negative pressure!

9. Substance Xylem Phloem
Typical Ranges for Components of Xylem and Phloem Saps in Higher Plants
Concentrations (g mL-1)
Substance Xylem Phloem
Sugars Absent 140, ,000
Amino acids , ,000 P
K ,800-4,400 Ca Mg Mn Zn Cu B
NO ,500-2, Absent NH

10. What is photosynthesis?
The conversion of electromagnetic energy to chemical energy
Light photons supply the energy to remove the carbon from carbon dioxide and link them together to form a compound of glucose.
light
6 CO2 + 6 H2O C6H12O6 + 6 O2
Recall I mentioned that you learned 1 of the 2 most important chemical equations, well this is the other!

11. 1st Law of thermodynamics
Energy can not be created or destroyed; it can only undergo conversion from one form to another
Therefore photosynthesis does not create energy

12. Photosynthesis
Process of converting light energy to chemical energy that is useful for biological systems.
Almost all energy on this planet uses energy originally derived through the process of photosynthesis.

13. The Overall Equation for Photosynthesis
The reactants and products of the reaction
Light
energy
Photo- synthesis
Carbon
dioxide
Oxygen
gas
Water
Glucose
Unnumbered Figure 7.1

14. How plants capture electromagnetic energy
Plant pigments absorb light energy
chlorophyll a, chlorophyll b, carotenoids
Chlorophyll a

15. Where are the pigments located within a plant cell?
chlorophyll within the thylakoid membrane

16. Light dependent reactions:
chemical equation for photosynthesis
light
6 CO2 + 6 H2O C6H12O6 + 6 O2
Light dependent reactions:
2H2O + 2ADP +2Pi +2NADP+  O2 + 2ATP + 2NADPH + 2H+
Energy from 4 photons of light
No CO2 used
O2 produced as a waste product
H  H+ and NADPH, electrons from H end up in NADPH
NADPH is 2 times greater in energy than ATP

17. Light independent reactions
6CO2  C6H12O O2 used in other reactions
Energy and 12H
Heat
Energy
Heat
12NADPH  12 NADP and
18 ATP 18ADP + 18Pi
Light dependent reactions + light independent reactions
6CO2 + 12NADPH +18ATP + 12H2O + 12H+
 C6H12O6 + 12NADP+ +18PiH2O + 18ADP
Summary equation again:
6 CO2 + 6 H2O C6H12O6 + 6 O2

18. Three phases of photosynthesis
Sunlight energy captured
Using sunlight energy to synthesize ATP (adenosine triphosphate)
Using ATP to synthesize organic compounds from carbon dioxide
(fixation of inorganic carbon)
Bottom line: we went from light energy to electrical energy and then from electrical energy to chemical bond energy.

19. Why a carbohydrate?
If a plant can produce an energetic molecule, like ATP, why bother synthesizing glucose then later convert it back to ATP? PORTABILITY
ATP and NADPH are fairly unstable compounds. Imagine trying to send these compounds around without losing energy as they go.

20. Summary of Photosynthesis
cellular respiration
cellulose starch
other organic compounds

21. Respiration vs. Photosynthesis?
Respiration takes energy stored in the chemical bonds of glucose and converts it to ATP.
Photosynthesis takes energy from light and converts it into glucose.

22. 6 CO2 + 6 H2O  C6H12O6 + 6 O2 C6H12O6 + 6O2  6CO2 +6H2O
Photosynthesis
6 CO2 + 6 H2O  C6H12O6 + 6 O2
Respiration:
C6H12O6 + 6O2  6CO2 +6H2O
C6H12O6+ 6O2
Photosynthesis
Respiration
Light Energy
Heat Energy
6H2O + 6CO2

23. You should be able to:
Identify the main regions of a plant (roots, stems and leaves) identify their main functions, the structures within each region that help them carry out those functions, and the physical factors that affect each.
Explain how the physical environment, particularly water and light availability, can affect plant growth form.
Identify the main purpose of photosynthesis.
For both the light dependent and light independent reactions be able to identify:
The source of energy driving each set of reactions, and where it ends up.
The important molecules needed by each set of reactions.
The products of each set of reactions.
Explain why glucose is a better way of transporting energy than ATP or NADPH
Explain the importance of the polarity of water to the process of getting water from the roots to the leaves.
Explain the importance of the products of photosynthesis to the process of respiration and vice-versa.
Explain the energetic relationship between photosynthesis and respiration.