A16-Photosynthesis

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Transcript A16-Photosynthesis

Photosynthesis
How do plants get energy?
Photosynthesis – process plants use to trap sun’s
energy and build carbohydrates (glucose) that
store energy.
Formula:
6CO2 + 6H2O + energy → C6H12O6 + 6O2
6 carbon dioxide + 6 water + energy→ 1 glucose + 6 oxygen
2 Phases of Photosynthesis
1.
2.
2 Phases of Photosynthesis:
1. Light-dependent Reactions
– Takes place in chloroplasts
– Chloroplast contains pigment called chlorophyll
which is green because it reflects green light.
(In fall, trees absorb chlorophyll and other colors
show through.)
light energy (from Sun) → chemical energy (ATP)
2 Phases of Photosynthesis:
2. Light-independent Reactions or Calvin Cycle
or Dark Reactions
– Does not require light
– Uses ATP (from light reactions) to convert CO2 to
glucose
How do plants regulate water & gas exchange?
Guard cells on the underside of leaves open to
let in CO2 and O2 (waste product) and some
H2O out (plant “sweating”). The cells are
closed when they become flaccid & lose
water. The cells open when they are full of
water & swollen. This process is called
transpiration.
Guard Cells
Guard Cells