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: 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