Download Notes 2-3

Notes 1-8
Objective: Recognize the importance of photosynthesis in using light
energy as part of the chemical process that builds plant material.
The process by which a cell captures energy in sunlight and uses it to make
food is called photosynthesis. Photo means “light”. Synthesis means
“putting together”.
Nearly all living things obtain energy either directly or indirectly from the
energy of sunlight captured during photosynthesis. During photosynthesis,
plants and some other organisms use energy from the sun to convert carbon
dioxide and water into oxygen and sugars. There are 2 stages to this
process.
Stage 1: Energy from sunlight is captured mostly in the leaves. The leaves
are green because of the chlorophyll found in the chloroplasts in the leaves
cells. The chlorophyll absorbs the light, kind of like a solar cell in a
calculator absorbs light to power it.
Stage 2: The captured energy is used by the cells to produce sugars. The
cell also uses water (H2O) and carbon dioxide (CO2) in this process. The
water moves up the roots and stems from the soil and carbon dioxide enters
the plant through small pores in the underside of the leaves (stomata). The
captured energy causes chemical reactions between the water and carbon
dioxide. The chemical reaction produces sugar (C6H12O6) and oxygen (O2).
The leaves cells use the sugar (food) to carry out its functions while the
oxygen exits the leaf to go into the atmosphere.
Photosynthesis Equation (Know this!)
6 CO2 + 6 H2O + light energy  C6H12O6 + 6 O2