CHAPTER 8 • HOW DO FOOD STUFFS COME INTO BEING? 



1 How do new supplies of organic material originate? 



2 Could all living things make their own food if there were no 



others from whom they could take it? 



3 Is it true that plants breathe in what animals breathe out, and 



that animals breathe in what plants breathe out? 



4 Can plants live without roots? 



5 Where does the carbon in foods come from? 



6 Where does the nitrogen in foods come from? 



7 Why is it necessary to buy nitrogenous fertilizers when there 



is so much nitrogen in the air? 



8 Is soil important now that we can grow plants without it? 



9 Why do farmers prefer valley lands to upland farms? 

 10 Is there danger of exhausting our soil resources? 



When proteins, fats, and carbohydrates become assimilated into the pro- 

 toplasm of any plant or animal, they are still available as food for other 

 living beings. But when any of this material becomes oxidized, it is thrown 

 out of the world of living things. Now living matter can continue to live 

 only at the expense of other living matter, and living matter is constantly 

 being destroyed (oxidized). How, then, can the total amount of protoplasm 

 increase, or even remain the same? The answer to this question was found 

 in the discovery that the green parts of plants create new organic foods 

 out of inorganic materials. But how can green plants make new organic 

 foods when other living things cannot do so ? Out of what do plants make 

 these foods ? 



How Is Organic Material Made Anew? 



A Manufacturing Process^ The making of organic substances out of 

 inorganic materials may be compared to a manufacturing process. In every 

 such process there must be (1) raw material, (2) tools or machines that 

 work on the material, and (3) energy to drive the tools or machines. 

 There is of course (4) a main product, and sometimes there are (5) left- 

 over wastes, or by-products. 



The simplest organic product that we can recognize in a plant is a 

 sugar. 



The raw materials used by the plant in making carbohydrates, or sugars, 

 are water and carbon dioxide. 



The plant's machines or instruments differ from those with which we 

 are familiar and which consist of wheels and levers or other moving parts. 



iSee Nos. 1-4, pp. 157-158. 

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