Chapter 3 Section 3 Photosynthesis Sources of Energy

Chapter 3, Section 3 Photosynthesis

Sources of Energy Photosynthesis: Photosynthesis the process by which a cell captures energy in sunlight and uses it to make food o 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

Review Autotroph o an organism that makes their own food o What are some examples? Heterotroph o an organism that cannot make their own food o What are some examples? Fungi– absorb their food from other organisms

The Two Stages of Photosynthesis 1. Capturing the sun’s energy 2. Producing sugars Both stages must occur in the correct order

Stage 1: Capturing the Sun’s Energy capturing process occurs mostly in leaves The green color comes from pigments– pigments colored chemical compounds that absorb light The MAIN photosynthetic pigment in chloroplasts is called CHLOROPHYLL Chlorophyll captures light energy and uses it to power the second stage of photosynthesis…

Stage 2: Using Energy to Make Food Cell uses captured energy to produce sugars The cell needs two raw materials 1. 2. water – enters plant through roots and move upward to the leaf carbon dioxide– dioxide enters through openings called stomata Once in the leaves the water and carbon dioxide move into the chloroplasts….

Stage 2: Using Energy to Make Food Inside the chloroplasts undergo a series of chemical reactions Chemicals are the products of the reactions (2) o Six-carbon sugar (use this energy to carry out cell functions) o Oxygen (exits leaf through stomata) Fun Fact: Almost all oxygen in Earth’s atmosphere was produced by living things through the process of photosynthesis

The Photosynthesis Equation Raw Materials The arrow stands for YIELDS Products

What happens to the sugar produced in photosynthesis? Plants use it for food Some sugar is made into other compounds, such as cellulose Some sugar is stored in the plant’s cells for later use