1. Photosynthesis
Horticulture

2. objectives
explain in general terms what photosynthesis is.
write the chemical equation for photosynthesis and explain it
list the four things that must be present for photosynthesis to occur
detail the factors that affect photosynthesis

3. photosynthesis
comes from the word “photo” light and “synthesis” put together.
All animal depend on plants at some point in the food chain
Its estimated that 620,000,000,000 tons of carbon are converted by plants from the earths atmosphere every year.

4. Photosynthesis: makes plants unique
basic reaction that sustains all life
process that converts the sun’s energy into a form humans and other living creatures can use (plant material)
converts light energy into chemical energy that plants use to make food

5. The Light Spectrum Light is made up of many different “rays”
Light rays are measured in nanometers

6. White Light White light is made up of many different colors: Orange
Red
Yellow
Green
Blue
Indigo
Violet

7. Prism

8. Plant Pigments Each wavelength of light is unique
Plants produce a chemical component which reflects only a certain wavelength of visible light
This is called a pigment
This is what makes animals, plants, and everything appear colorful!!!

9. Pigments Absorption
More important than which wavelength they reflect is which they ABSORB.
Pigments are the means by which the E of the sunlight is captured to be used in photosynthesis

10. This increases the amount of light that is absorbed.
Pigments
Because each pigment only absorbs a narrow range of light, it is necessary to have multiple pigments.
This increases the amount of light that is absorbed.

11. Process Photosynthesis occurs in plant organelles called Chloroplast
CHORLOPLAST are present mostly in leaves, but also in green stems and unripe fruit.
Can only occur when the chemical CHLOROPHYLL is present within the chloroplast
Trap the energy from the light and converts it into a form useable to the plant

12. Chlorophyll: A complex molecule Different types of chlorophyll
All photosynthetic organisms have chlorophyll A
Absorbs light energy from violet-blue and orange-red wavelengths.
Shorter wave lengths = more energy
Little from green- yellow- orange

13. Types of Chlorophylls
For those waves of light that Chlorophyll A cannot absorb, there are accessory pigments:
chlorophyll B
xanthophylls
carotenoids (beta-carotene)
These absorb the longer waves, with less energy such as:
Green, yellow, and oranges
Don’t actually produce energy, but transfer it to the chlorophyll A.

14. Photosynthesis Process
“fixes” carbon (from CO2 in the atmosphere) into a solid state.
Produces oxygen as an important by-product.
Major energy yielding chemicals produced is glucose (C6H12O6)- a sugar or carbohydrate

15. Photosynthesis requires
1. A living, healthy plant
2. An amble supply of CO2 from the atmosphere
3. Water (H2O)—from soil or atmosphere
4. Light, usually from the sun

16. The process is a series of complex reactions that is basically this:
Carbon dioxide from the atmosphere + water combine in the presence of light = energy and chlorophyll to from sugar and oxygen

17. Sun light /
CO2 + H2O = C6H12O6 + O2 \
Chlorophyll

19. Stages of Photosynthesis
2 stage process
Light Dependent process
Dark Phase or Light Independent Phase

20. Light Dependent process
Requires direct energy of light
Cells trap the energy from the sun and use it to split water molecules to get the Hydrogen
Hydrogen is converted to other chemicals that are used in the dark phase

21. Dark Phase or Light independent process
Carbon dioxide from the atmosphere is captured and modified by the addition of hydrogen to form carbohydrates (sugars) that plants use for food and other processes

22. Products of Photosynthesis
Glucose,
the sugar formed by photosynthesis does not accumulate in the plants
Used as a source of energy by the plant or it is transformed into other substances:
Sucrose
Starch stored in cells, seeds, roots, and tubers
Cellulose: used in construction of plant cell walls
Converted to fats and oils in the seeds
Converted to from proteins

23. Factors Affecting Photosynthesis
Light Quality
Light Intensity
Light Duration or length
Amount of Carbon Dioxide
Temperature
Water availability

24. Worldwide, photosynthesis fixes vast quantities of carbon from the atmospheric CO2 and converts it to carbohydrates in the plants.
Plants then produce O2.
As the levels of CO2 are increasing in our atmosphere do to pollution by human sources and plants and forest around the world

25. Quiz: 1. what is the definition of photosynthesis?
2. What are the two products of the photosynthesis process?
3. What four factors must be present for photosynthesis to occur?
4. What plant cell organelle is responsible for trapping the light energy and must be present for photosynthesis to occur?
5. List 3 factors that affect photosynthesis.