LO’s Explain why photosynthesis is so important to energy and material flow for life on earth

LO’s

1.Explain why photosynthesis is so important to energy and material flow for life on earth

2.Know why plants tend to be green in appearance

3.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

• Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water

AN OVERVIEW OF PHOTOSYNTHESIS

Carbondioxide

Water Glucose Oxygengas

PHOTOSYNTHESIS

Oxygen – used for cellular respiration

CO2 and water are waste products of cellular respiration

WHYWHY ARE ARE PLA PLANTS NTS GREGREEN? EN?

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

Sunlight minus absorbed Sunlight minus absorbed wavelengths or colors equals wavelengths or colors equals the apparent color of an the apparent color of an object.object.

The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others.

Reflected light

Why are plants green?

Reflected lightTransmitted light

Energy needs of life

All life needs a constant input of energy1. 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 : 1.Light reaction ( with a solar energy captured and transformed into chemical energy

2.Calvin cycle – the chemical energy is used to make organic molecules

• The location and structure of chloroplasts

LEAF CROSS SECTION MESOPHYLL CELL

LEAF

Chloroplast

Mesophyll

CHLOROPLAST Intermembrane space

Outermembrane

Innermembrane

ThylakoidcompartmentThylakoidStroma

Granum

StromaGrana

Photosynthesis occurs in chloroplast

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

• 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

LightChloroplast

Lightreactions

Calvincycle

NADP

ADP+ P

• The light reactions convert solar energy to chemical energy– Produce ATP & NADPH

AN OVERVIEW OF PHOTOSYNTHESIS

Plants and animals need each other to survive.