Sin título

Role of Photosynthesis

• -Formation of fossil fuels
• Used by plants to make food
• Plants are eaten by animals
• Forms oxygen required by living things to obtain the energy required for respiration

Photosynthesis: Light is absorbed

• Sunlight is trapped by chlorophyll.
• Chlorophyll is found in cell organelles called chloroplasts.
• Photosynthesis takes place in the chloroplast

2.Water is split

• Energy is used in the chloroplasts to split water molecules
• Hence Hydrogen(protons), oxygen and electrons are formed

3.The products of of the splitting of water

• Electrons passed through the chlorphyll
• The protons are released into a pool of protons in the chloroplast for later use
• Oxygen may pass from the chloroplast to the cytoplasm and eventually out of the leaf and into the atmosphere
• Or may be used within the cells of the leaf for the process of respiration

4.Light energizes electrons

• Some of the sunlight energy is trapped by the chlorphyll is passed to the electrons in the chlorphyll to form high energy electrons

5.Glucose is formed

• The high energy electrons with the protons from the pool of protons combine with carbon dioxide to form a carbohydrate called glucose
• 

Increasing the rate of photosynthesis

• Artificial light source can be used
• Artificial source carbon dioxide

Light Stage Dark Stage

• Dependant on light
• Energy provided by light
• No enzyme required
• Independant light
• energy in the reaction is provided by Atp which was made in the light stage
• Enzyme controlled reaction

Light Stage

• In each cluster the different pigmentation absorb light energy of different wavelenghths. Hence to absorb asmuchlight energy as possible.
• The different pigments transfer energy from one pigment to another until it reaches the chlorophyll molecule and to the electron acceptor. Here the energy is transferred to the electrons causing them to be energised.
• Cylic Electron flow pathway 1
• The high energy electrons pass from the chlorophyl molecule to an electron acceptor.Then they pass from an electron acceptor to a seriesof electron acceptors then back to the chlorphyl molecule.When the electrons return they lose energy thislost energy is TRAPPEDby ADP and phosphate toform ATP AND WATER.
• Non cyclic Electron flow
• Two high energy electronsleave the chlorophyll molecule to theelectron acceptor.Then they go through aseries of electron acceptors but do not return to the chlorophyll molecule.Inseatd the energy islost as the electrons go through a series of electron accpeotrs,the energy lost is used to make Atp.
• The two electrons combine with Nadp+ to form NADP-.
• The chlorophyll molecule is shortof electrons so water issplit
• One of the protons is attracted to the Nadp- to form Nadph
• The products of thelight stage are as stated.
• -Atp used as energy for the dark stage
• -Nadph provdes the electrons and protons for the dark stage reactions
• ​​​​​​​-Oxygen used for respiration or released to the atmosphere.

Dark stage

• The dark stage takesplace in the stroma.
• Reactions are controlled by enzymes
• Carbon dioxide from the air or from respiration enters the chloroplast
• HYDROGEN IONS AND Electrons ARE RELEASED from the NADPH to convert carbon dioxide to a carbohydrate