Photosynthesis

Trapping Energy from Sunlight The process that uses the sun’s energy to make simple sugars is called photosynthesis.

How do plants make energy & food? Plants use the energy from the sun to make ATP energy to make sugars glucose, sucrose, cellulose, starch, & more sun ATP sugars

What do plants need to grow? The “factory” for making energy & sugars chloroplast Fuels sunlight carbon dioxide water The Helpers enzymes Make ATP! Make sugar! I can do it all… And no one even notices! sun CO2 ATP enzymes sugars H2O

Energy and Life Plants and some other types of organism are able to use light energy from the sun to produce organic compounds (glucose). Autotrophs – organisms that are able to synthesize their own food. Heterotrophs – obtain energy by consuming other organisms.

Photosynthesis Plants use the energy of sunlight to convert water and carbon dioxide into oxygen and high energy carbohydrates.

Stomates & Guard Cells in the leaf Function of stomates CO2 in O2 out H2O out gets to leaves for photosynthesis Function of guard cells open & close stomates guard cell stomate

Structure of a Leaf Xylem – carries water from the roots to leaves. Phloem – carries food (glucose) from leaves to the roots. Stomata – tiny holes in bottom of the leaf that function in gas exchange. Guard cells – control the opening and closing of guard cells.

Trapping Energy from Sunlight Photosynthesis happens in two phases. The light-dependent reactions convert light energy into chemical energy. (ATP) 2. The molecules of ATP produced in the light-dependent reactions are then used to fuel the Calvin Cycle or light-independent reactions that produce simple sugars. The general equation for photosynthesis is written as 6CO2 + 6H2O→C6H12O6 + 6O2

THE LIGHT REACTIONS: CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY Visible radiation drives the light reactions Certain wavelengths of visible light drive the light reactions of photosynthesis X-rays Micro- waves Radio waves Gamma rays UV Infrared Visible light Wavelength (nm)

Light and Pigments In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule found in chloroplasts. Plants gather the suns energy with light absorbing molecules called pigments (chlorophyll).

Why are leafs green? There are two types of chlorophyll, chlorophyll a and chlorophyll b. These pigments absorb red and blue light, and reflect green.

Other Pigments Carotenoids, which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils. Anthocyanins, which give color to such familiar things as cranberries, red apples, concord grapes, blueberries, cherries, strawberries, and plums. Why do leaves change colors in the autumn? During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed. The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.

Paper Chromotography Paper chromatography is a technique for separating and identifying mixtures that are or can be colored, especially pigments found in plants.

Rate of Photosynthesis Amount of Water available Temperature Light Intensity

Comparing photosynthesis and Cellular Respiration