1. Topic 2.9 Photosynthesis Review
Essential idea: Photosynthesis uses the energy in sunlight to produce the chemical energy needed for life.

2. 2.9 Photosynthesis
Nature of science: Experimental design—controlling relevant variables in photosynthesis experiments is essential. (3.1)
Understandings:
Photosynthesis is the production of carbon compounds in cells using light energy
Visible light has a range of wavelengths with violet the shortest wavelength and red the longest
Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colours
Oxygen is produced in photosynthesis from the photolysis of water
Energy is needed to produce carbohydrates and other carbon compounds from carbon dioxide
Temperature, light intensity, and carbon dioxide concentration are possible limiting factors on the rate of photosynthesis
Applications and Skills:
Application: Changes to the Earth’s atmosphere, oceans, and rock deposition due to photosynthesis
Skill: Drawing an absorption spectrum for chlorophyll and an action spectrum for photosynthesis
Skill: Design of experiments to investigate the effect of limiting factors on photosynthesis
Skill: Separation of photosynthetic pigments by chromatograph (Practical 4)

3. U 2.9.1 Photosynthesis is the production of carbon compounds in cells using light energy
What is the general equation for photosynthesis?
CO2 + H2O + light  C6H12O6 + O2
Carbon dioxide + water + light  glucose + oxygen
What type of organisms perform photosynthesis?
Autotrophs, photoautotrophs

4. U Visible light has a range of wavelengths with violet the shortest wavelength and red the longest
What type of wavelength has the highest energy?
Short wavelength
X-ray and ultraviolet
What type of wavelength has the lowest energy?
Long wave lengths
Infrared and radio waves
Range of visible light is 400 to 700 nanometers

6. U Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colors
What are pigments?
Substances that absorb light
What is the main photosynthetic pigment?
Chlorophyll
Why are plants green?
Chlorophyll absorbs red and blue light and reflects green light

9. U 2.9.4 Oxygen is produced in photosynthesis from the photolysis of water
What is photolysis?
Splitting of water only when light is present
Oxygen is released as a byproduct: 4 H2O  4e- + 4H+ + O2
HL- what part of photosynthesis does this occur?
Light-dependent reactions

10. U 2.9.5 Energy is needed to produce carbohydrates and other carbon compounds from carbon dioxide
What type of reaction is photosynthesis?
Endothermic
Where does this energy come from?
Light
Energy from light is converted to chemical energy in carbohydrates
HL- is ATP made in the light-dependent or light-independent reactions?
Light-dependent
HL- How is ATP made?
Via electron transport change and chemiosmosis

12. U Temperature, light intensity, and carbon dioxide concentration are possible limiting factors on the rate of photosynthesis
Photosynthesis can be effected by three external factors: temperature, light intensity, and carbon dioxide concentrations
What type of factors are these?
Limiting factors

13. A 2.9.1 Changes to the Earth’s atmosphere, oceans, and rock deposition due to photosynthesis
What were the first organisms to perform photosynthesis?
Prokaryotes
Algae and plants followed
What is the Great Oxidation Event?
Oxygen levels rose to 2% by volume 2,200 mya
At the same time Earth experienced a glaciation possibly due to decrease in greenhouse gases
What are two greenhouse gases?
Carbon dioxide and methane

14. A 2.9.1 What changes were seen in the oceans?
Oxidation of dissolved iron in the water
What type of formation in the rock occurred?
Banded iron formation occurred- layers of iron oxide alternating with other minerals
Important iron ores which are sources of steel
Oxygen in atmosphere eventually rose to 20% or more which allowed for evolution of multicellular organisms

16. S 2.9.1 Drawing an absorption spectrum for chlorophyll and an action spectrum for photosynthesis
Absorption spectrum- graph showing percentage of light absorbed at each wavelength by pigment or group of pigments
Action spectrum- graph showing rate of photosynthesis at each wavelength of light
x-axis is wavelength is nanometers (nm) 400 to 700/800 nm for both
Action spectrum y-axis- amount of photosynthesis (% of max rate) from 0 to 100%
Absorption spectrum y-axis- % absorption from 0 to 100%
Plot data points and then draw a smooth curve

18. S 2.9.2 Design of experiments to investigate the effect of limiting factors on photosynthesis
Independent variable
Temperature, light intensity, carbon dioxide
Dependent variable
What you are measuring  rate of photosynthesis, how?
Biomass, carbon dioxide uptake, oxygen production
Controlled variables
You need to make sure to keep the other limiting factors controlled

19. S 2.9.3 Separation of photosynthetic pigments by chromatograph (Practical 4)
Chloroplasts contain pigments such as chlorophyll and accessory pigments
Pigments can be separated by chromatography
A spot containing pigments is extracted from a leaf tissue and is place at the end of a strip of thin layer chromatograph paper that is coated with a porous material
A solvent is allowed to run up the strip to separate the pigments