Photosynthesis

Contents
What is photosynthesis?
Overview
Where does photosynthesis occur?(Leaf)
Structure of leaf
Why do plants need photosynthesis?
Requirements
Photosynthesis: the chemical process
Benefits of photosynthesis

What is photosynthesis?
The biochemical process in which sun light fixes carbon dioxide into glucose in the
presence of water is
called 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 CO 2 + 6 H 2 0 + sunlight  C 6 H 12 O 6 + 6 O 2
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 CO 2 and O 2 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 6CO 2 + 6H 2 O + ENERGY C 6 H 12 O 6 + 6O 2 CARBON DIOXIDE WATER GLUCOSE OXYGEN

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.

Advantages
Basic source of energy for all livings
Production of oxygen
Healthy environment
Lessen global warming

PHOTOSYNTHESIS AND LIFE
During the process of photosynthesis, oxygen is produced. We use this oxygen to breathe.

photosynthesis and respiration PHOTOSYNTHESIS CELL ACTIVITIES RESPIRATION SUN RADIANT ENERGY GLUCOSE ATP(ENERGY)

Photosynthesis and Respiration C 6 H 12 O 6 + GLUCOSE 6O 2 OXYGEN 6CO 2 + CARBON DIOXIDE 6H 2 O + ENERGY WATER ATP

Photosynthesis

by Muhammad Shahid on May 03, 2010

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Photosynthesis — Presentation Transcript