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LO’s Explain why photosynthesis is so important to energy and material flow for life on earth Know why plants tend to be green in appearance Understand that photosynthesis is a two fold process composed of the light-dependent reactions (i.e., light reactions) and the light independent reactions.
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LO’s Explain why photosynthesis is so important to energy and material flow for life on earth Know why plants tend to be green in appearance Understand that photosynthesis is a two fold process composed of the light-dependent reactions (i.e., light reactions) and the light independent reactions
Basic questions?? • What do plants eat? • Why do plants need light? • Why do plants need water? • Why are plants green?
Photosynthesis • Process that captures energy from the sun • Energy stored in carbohydrates • Oxygen is byproduct
Photosynthesis • Almost all plants are photosynthetic autotrophs, as are some bacteria and protists • Autotrophs generate their own organic matter through photosynthesis • Sunlight energy is transformed to energy stored in the form of chemical bonds
AN OVERVIEW OF PHOTOSYNTHESIS • Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water Carbondioxide Water Glucose Oxygengas PHOTOSYNTHESIS
CO2 and water are waste products of cellular respiration Oxygen – used for cellular respiration
WHY ARE PLANTS GREEN? Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).
Sunlight • Electromagnetic energy (radiation) • Packets of energy (photons) • Range of wavelengths
Plant Pigments • Found in chloroplasts • Absorb some visible wavelengths
Plant Pigments • Carotenoids – absorb photons of green, blue & violet wavelengths • Chlorophylls – absorb photons of red & violet-blue wavelengths
The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light Sunlight minus absorbed wavelengths or colors equals the apparent color of an object.
Why are plants green? Reflected light Transmitted light
Energy needs of life All life needs a constant input of energy 1. Heterotrophs (Animals) Get energy from “eating others” Make energy through respiration • 2. Autotrophs “self-feeder” (Plants) • Produce their own energy • Convert energy of suclight -- chemical energy • Make energy and synthesise sugars through PHOTOSYNTESIS
Photosynthetic Autotrophs • Solar energy powers glucose synthesis • Uses • Carbon dioxide • Water • Captured energy • Produces • Glucose • Oxygen
Heterotrophs • Consume other organisms • Cannot produce their own food • Food ultimately comes from autotrophs
Photosynthesis – looks and sounds like a complex process • Two stages of Photosynthesis : • Light reaction ( with a solar energy captured and transformed into chemical energy • Calvin cycle – the chemical energy is used to make organic molecules
Chloroplast LEAF CROSS SECTION MESOPHYLL CELL • The location and structure of chloroplasts LEAF Mesophyll Intermembrane space CHLOROPLAST Outer membrane Granum Innermembrane Grana Stroma Thylakoidcompartment Stroma Thylakoid
LIGHT ENERGY WATER • Light energy is used to split water molecules – known as ‘Photolysis’ –chemical is broken down by photons • ATP is produced during photolysis • ATP and H ions will be used to fix CO2 to make organic molecules • Photosynthesis relies on water and sunlight for its initial reaction
AN OVERVIEW OF PHOTOSYNTHESIS Light • The light reactions convert solar energy to chemical energy • Produce ATP & NADPH Chloroplast NADP ADP + P Calvin cycle • The Calvin cycle makes sugar from carbon dioxide • ATP generated by the light reactions provides the energy for sugar synthesis • The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light reactions