ContentsWhat is photosynthesis?OverviewWhere does photosynthesis occur?(Leaf)Structure of leafWhy do plants need photosynthesis?RequirementsPhotosynthesis: the chemical processBenefits of photosynthesis
What is photosynthesis?The biochemical process in whichsun light fixes carbon dioxide intoglucose in the presence of water iscalled photosynthesis.
Photosynthesis in Overview• Process by which plants and other autotrophs store the energy of sunlight into sugars.• Requires sunlight, water, and carbon dioxide.• Overall equation:6 CO2 + 6 H20 + sunlight C6H12O6 + 6 O2• Occurs in the leaves of plants in organelles called chloroplasts.
Where does photosynthesis occur?• Photosynthesis occurs in the leaves of a plant.
Leaf Structure• Most photosynthesis occurs in the palisade layer.• Gas exchange of CO2 and O2 occurs at openings called stomata surrounded by guard cells on the lower leaf surface. Palisade Spongy
Chloroplast Structure• Inner membrane called the thylakoid membrane.• Thickened regions called thylakoids. A stack of thylakoids is called a granum. (Plural – grana)• Stroma is a liquid surrounding the thylakoids.
Pigments• Chlorophyll A is the most important photosynthetic pigment.• Other pigments called antenna or accessory pigments are also present in the leaf. – Chlorophyll B – Carotenoids (orange / red) – Xanthophylls (yellow / brown)• These pigments are embedded in the membranes of the chloroplast in groups called photosystems.
Why do plants need photosynthesis?• Glucose is the food for the plant. It gives the plant energy to grow.• They do photosynthesis to gain energy.
Requirements for photosynthesis to occur.• Light• Carbon Dioxide• Water• But the most important among these is sunlight
Photosynthesis: The Chemical Process• Photosynthesis is a chemical process.• It occurs in two main phases. – Light reactions – Dark reactions (the Calvin Cycle)
Light Reactions• Light-dependent reactions occur on the thylakoid membranes. – Light and water are required for this process. – Light reactions are the “photo” part of photosynthesis. – Light is absorbed by pigments and is transformed into ATP and NADPH molecules
Dark Reactions• Dark reactions (light-independent) occur in the stroma. – Dark reactions are the synthesis parts of photosynthesis – Trapped energy by pigments is converted into chemical ennergy – Carbon dioxide is “fixed” into glucose – ATP and NADPH molecules created during the reaction is responsible for production of this glucose
EQUATION FOR PHOTOSYNTHESIS WATER OXYGEN6CO2 + 6H2O + ENERGY C6H12O6 + 6O2 GLUCOSECARBONDIOXIDE
How much glucose does a plant make?• Plants make enough glucose to be used during the night and on cloudy days when they don’t get sunlight• The extra glucose is stored in the plant’s leaves and other parts.
AdvantagesBasic source of energy for all livingsProduction of oxygenHealthy environmentLessen global warming
PHOTOSYNTHESIS AND LIFE• During the process of photosynthesis, oxygen is produced. We use this oxygen to breathe.
photosynthesis and respiration SUN RADIANT ENERGYPHOTOSYNTHESIS RESPIRATION CELL ACTIVITIES GLUCOSE ATP(ENERGY)
Photosynthesis and Respiration CARBONGLUCOSE DIOXIDE ATPC6H12O6 + 6O2 6CO2 + 6H2O + ENERGY OXYGEN WATER