ASSIMILATION 39 



This union is a type of oxidation. The energ}' released from 

 food was stored up at the time of the manufacture of food (photo- 

 synthesis and protein-formation) in a potential, latent or dormant 

 form. The sun is the source of this enercjv. When oxidation of 

 food occurs, the potential energy is converted and released as 

 kinetic, an active form of energy. In plant cells, the kinetic 

 energy takes the form of work energy or heat energy, resulting 

 in the maintenance of a normal temperature. As a part of this 

 oxidation process, w^astes, carbon dioxide and ivater, are formed. 



|CHpc(|)| |CHaO(DT^p) 



+ + 



|r r»eleccSeoL y 



eneri 



COa -^-HsO +1 -^ C0^fi20+f + xvcclbes 



The green plant cell builds up carbohy- A protein may be broken down during oxi- 



drates which contain bound-up energy. This dation and energy released. Among the 

 may later be set free as heat or work energy. resulting wastes are some containing nitrogen. 



These the cell gives off. If respiration takes place at the time 

 the plant is actively making sugar, the carbon dioxide and some 

 of the water resulting from oxidation may be retained for further 

 photosynthesis. Nitrogenous wastes are probably retained for 

 further manufacture of protein. The oxygen released during 

 photosynthesis may be retained for oxidation although it is usually 

 given off. Thus a balance of materials may be maintained. Res- 

 piration, then, involves the taking in of oxygen, the oxidizing of 

 certain food materials present, and releasing energy and waste 

 products. The respiration process is the means of releasing all of 

 the energy needed by the plant. 



Assimilation. The protoplasm of the cell is built of the elements 

 C-H-0-S-N-P, and sometimes others. After protein manufac- 

 ture is accomplished, the lifeless protein together with water and 



