Photosynthesis

The Sun!! Photosynthesis Where does the energy come from that sustains all life? The Sun!! Well most of it anyway……

What is photosynthesis? In the process of photosynthesis, plants convert the energy of sunlight into the energy in the chemical bonds of carbohydrates-sugars and starches.

Why is Photosynthesis important? Plants that are able to use a source of energy, such as sunlight, to provide food directly from simple inorganic molecules are known as autotrophs. This is made possible through photosynthesis.

WHAT IS THE DIFFERENCE BETWEEN A HETEROTROPH & AN AUTOTROPH? Quick Concept Check: WHAT IS THE DIFFERENCE BETWEEN A HETEROTROPH & AN AUTOTROPH?

Photosynthesis The process of changing light energy to chemical energy Energy stored as sugar Occurs in plants and some algae Plants need light energy, CO2, and H2O Takes place in the chloroplasts, using chlorophyll, the green pigment in plants

What is photosynthesis? Chloroplasts are where photosynthesis occurs. Chloroplasts work much like solar cells found in calculators.

Chlorophyll Chlorophyll is the main pigment used in photosynthesis. A pigment is a molecule that absorbs some colors of light and reflects others.

Chlorophyll Chlorophyll absorbs mostly blue and red light, and reflects green light. This is why most plants look green.

Photosystems use some wavelengths of light but reflect others…

What happens during photosynthesis?

The Two Stages of photosynthesis 1. Plants capture light energy and use that energy to make glucose 2. Sunlight provides the energy needed by chlorophyll to change molecules of carbon dioxide and water into sugar (glucose) Oxygen is also released in this reaction

What happens during photosynthesis? Carbon dioxide enters the leaf through holes called stomata CO2 combines with the stored energy in the chloroplasts through a chemical reaction to make 6 carbon sugars (Glucose) & Oxygen Some of the sugar is used right away by the plant for energy; some is stored as starch; and some is built into plant tissue

The Photosynthesis Equation: LIGHT Carbon Dioxide + Glucose Water + Oxygen LIGHT 6 CO2 + 6 H2O C6 H12 O6 + 6O2

Self-Evaluation Questions In the process of photosynthesis, plants convert the energy of sunlight into what? Fill in the missing part of the equation for photosynthesis--Carbon dioxide + water yields what? (two things) What do you call plants that obtain their nutrients in organic molecules through photosynthesis? What do you call organisms that need to consume other organisms to obtain food?

Why is this important to us? We cannot make our own food (glucose, energy), we must get our food from plants. Plants are the first step in the food chain.

Why is this important to us? The oxygen released during photosynthesis is necessary for all living things. Photosynthesis occurred on Earth for billions of years before enough O2 was released to create an atmosphere rich in oxygen. This allowed animals to evolve on land (The earth's atmosphere presently contains 20% O2.)