1. 3.2 The leaf and photosynthesis

2. Photosynthesis
The leaf is a collection of tissues working together to carry out photosynthesis.
“Photo” “synthesis”
(light) (putting together)
[Putting together with light]

3. Photosynthesis The purpose of photosynthesis is to create energy
Water + Carbon Dioxide  Glucose + Oxygen
chlorophyll +light
6 H2O(l) + 6 CO2(g) > C6H12O6(aq) + 6O2(g)

4. Chloroplast Plant cells have organelles called chloroplasts
chloroplasts contain a green pigment called chlorophyll
cells containing chloroplasts are found in the ground tissue
light energy is absorbed by chlorophyll and turned into chemical energy (food for the plant)

5. Accessory Pigments
Chlorophyll is not the only pigment to capture light energy
Accessory pigments help protect the plant and capture the most energy possible
when temperatures get colder in the fall, chlorophyll disintegrates, revealing the other pigments underneath

6. Gas exchange in plants
Two main reactions that take place in plants and produce gases as products
Photosynthesis occurs in chloroplasts
Occurs in the light
Produces O2 and glucose
Cellular respiration occurs in the cytoplasm and mitochondria
Does not need light (as long as products from photosynthesis are available)
Glucose + oxygen  carbon dioxide + water + energy
C6H12O6 + 6O  CO H energy

7. Gas exchange in plants Photorespiration the two processes together
neither process can occur without the other

8. Observing photosynthesis
What is an easy way to measure photosynthesis?
Watch for a product of photosynthesis – OXYGEN

9. Something to think about:
The estimated amount of global energy from photosynthesis is 1.0 x 1021 joules.
That is joules
A hydrogen bomb is rated at 4.2 x 1015 joules
Photosynthesis produces the same energy as 238,095 hydrogen bombs!