Photosynthesis Ch. 9

Kansas Science Standards The sun is the primary source of energy for life through the process of photosynthesis. -plants and other photosynthetic organisms use energy from the sun to make glucose. - photosynthesis is a series of chemical reactions that takes place in a chloroplast.

Energy for Life; all living things need energy! Without energy, things tend to get messy. ex: your room, death Entropy: natural tendency toward disorder.

Autotrophs: get energy from the sun (or chemicals) to make own food. Heterotrophs: obtain energy from food it eats.

Energy is stored in the bonds between atoms and molecules (food) = chemical energy Plants change light energy into chemical energy which is stored in the bonds of glucose molecules.

Photosynthesis sun  6CO2 + 6H2O -------- 6O2 + C6H12O6 Carbon water oxygen glucose dioxide

Glucose = C6H12O6 The carbon in glucose comes from carbon dioxide (CO2) The hydrogen comes from water (H2O) The oxygen comes from CO2. The sun energy is stored in the bonds that hold the molecule together.

Plants take in carbon dioxide Pore on bottom of leaf called stoma (stomata pl.). Let CO2 into leaf. Let water vapor out.

Plants get water through roots Water is absorbed from soil through the roots.

Photosynthesis Photosynthesis happens in the chloroplast of a plant cell.

Chloroplast Thylakoids - membrane bound disks Granum - stack of thylakoids. Stroma - juicy inside. Double membrane around outside.

Plants gather sun energy Pigments: molecules that absorb certain wavelengths of light energy. Chlorophyll: pigments that absorb mostly blue and red wavelengths and reflect green.

Products of photosynthesis: Makes glucose to store energy. Also stores energy short term in the molecule ATP.

ATP: adenosine triphosphate Small molecule that stores small amounts of energy for a cell. Like pennies of energy compared to the $20 bill of glucose. Energy in ATP can be used anywhere in the organism.

ATP Energy is stored in the bond of the last phosphate group. Like a rechargeable battery. Absolutely necessary for life processes!

CO2 + H2O -----> O2 + C6H12O6

Factors affecting Photosynthesis Water Temperature Intensity of light Concentration of CO2

Overview of Photosynthesis

Two Parts: Light-dependent reactions Light-independent reactions

Light-dependent reactions Happens within thylakoid membrane. Chlorophyll energized by sunlight. (needs light) Sun energy moves to ATP and NADPH. (energy carriers) Oxygen produced.

NADPH Another energy carrying molecule like ATP. Like a rechargeable battery.

Light-independent reactions Happens in the stroma of chloroplast. Uses energy from light-dependent reactions (ATP and NADPH) to make glucose from CO2. Does not need light to work.