"Nutrition of Green Plant 

 Cells 



PHOTOSYNTHESIS is the cornerstone 

 upon which green plants have built their 

 mode of life. Possessing chloroplasts, typical 

 plants are able to use light energy as a driv- 

 ing force for the primary synthesis of organic 

 matter. Starting entirely -with inorganic 

 materials — water, carbon dioxide, and in- 

 organic salts — green plants can synthesize 

 all their needed carbohydrates, lipids, and 

 proteins, as well as a rich variety of other 

 organic compounds. In the last analysis pho- 

 tosynthesis accounts for the ultimate origin 

 of virtually all organic matter, ft is esti- 

 mated, indeed, that the total synthesis of or- 

 ganic compounds by all the green plants 

 of the world represents the utilization of 

 more than a billion tons of carbon every 

 day. These organic compounds, derived di- 

 rectly and indirectly from photosynthesis 

 contain virtually all the energy that is avail- 

 able for the support of life upon this earth. 

 This energy supports not only the life of 

 the green plants themselves, but also that 

 of animals and other organisms. Moreover, 



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photosynthesis maintains the free oxygen 

 content of our atmosphere, which otherwise 

 would tend to become exhausted. 



MECHANISM OF PHOTOSYNTHESIS 



Much of the light energy absorbed by the 

 green parts of a plant is utilized for the 

 synthesis of carbohydrate, particularly glu- 

 cose. Thus the main pathway of photosyn- 

 thesis, taken as an over-all process, can be 

 stated very simply: 



6CO0 -|- 6H 2 + energy 



(light) 

 chloroplast 



C ti H 12 R 



60 2 



glucose free oxygen 



This equation, however, reveals almost noth- 

 ing about the intrinsic mechanisms; nor does 

 it show any of the very interesting inter- 



