PHOTOSYNTHESIS | REACTION | PROCESS | IMPORTANCE

DEFINITION OF PHOTOSYNTHESIS 

• Is the process by which autotrophic organism use light enrgy to make sugar and oxygen gas by carbon dioxide and water. 

Reaction of photosynthesis 

1. Light dependent reaction
2. Light independent reaction

• Occurs in plants, algae and some prokaryotics.
• Stored as carbohydrate in their bodies.
• Anabolic (small molecule combined) 
• Endergonic (stores energy)

IMPORTANCE OF PHOTOSYNTHESIS 

Photosynthesis and sun energy

• A process that most biological organisms unable to perform. 
• A.T.P is used to power these processes. 
• Convert light energy into chemical energy in a form of glucose. 
• Then the process of cellular respiration converts energy in glucose to energy in the form of  A.T.P which is used to power biological process. 

Photosynthesis and carbon dioxide removal

• Convert carbon dioxide into oxygen. 
• During photosynthesis carbon dioxide leaves the atmosphere and enter the plant and leaves as oxygen. 
• A process which is ecologically and environmentally important in nature. 

Photosynthesis and the ecosystem 

• The energy produced by photosynthesis forms the basis of  virtually all terestrial and aquatic food chains.
• As a result photosynthesis is the ultimate source of carbon in the organic molecule found in most organisms. 
• The high O2 concentration in the atmosphere is derived directly from the light reactions of photosynthesis. 
• Prior to evolution of photosynthesis on earth,  the atmosphere was anoxic. 

Photosynthesis and side products 

• Solar energy, transformed by photosynthesis, is the source of countless vegetables, animal and organic side product. 
• Wood is very important material used as fuel and in many fields including construction. 
• Paper,  cotton and other natural fibres consist Of cellulose produced almost entirely by photosynthesyzing plants. 
• Wool depends on the energy sheeps obtain from grass,  and photosynthesis. 

Sites of photosynthesis 

• Photosynthesis occurs in chloroplasts , in certain plants organelles. 
• All green plants parts have chloroplast and carry out photosynthesis. 
• The leaves have the most chloroplasts. 
• The green colour come from chlorophyll  in the chloroplasts. 
• The pigment absorb light energy. 
• A chloroplasts contain

• Stroma, a fluid

•  Grana, stacks of thylakoids 

•  The thylakoids contain chlorophyll 

•  Chlorophyll is green pigment that captures light for photosynthesis. 

Why are plants green?  

• Plants cells have green chloroplasts. 
• The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigment ( chlorophylls, caretonoids) 
• Chlorophyll is located in the thylakoid membranes.
• Chlorophyll have Mg+ in the centre.
• Chlorophyll pigments harvest energy by absorbing certain wavelnghths (Blue 420nm Red 660nm are most important).
• Plants are green because the green wavelengths is reflected, not absorbed.