Sugbrr. 



H*0 



CHAPTER V 



FUNCTIONS OF 

 A GREEN CELL 



Nature's food factory. 



Some of the products. 



What does a green cell use for food? Where does it get this food? 

 What are the physiological activities of cells containing chlorophyll f 



In order to live, a green cell must carry on certain functions. Be- 

 cause these functions are carried on within the organism they are 

 called physiological functions. These functions may be classified 

 as nutritive, adaptive, and reproductive. The nutritive processes 

 can be further subdivided into absorption, food manufacture, food 

 storage, digestion, assimilation, secretion, growth, respiration, and 

 excretion. These have to do with the obtaining and the using of 

 food. The adaptive processes have to do with the way the organism 

 maintains itself and behaves in its environment. The reproduc- 

 tive processes have to do with the producing of new individuals. 



Absorption. The Spirogyra takes in carbon dioxide, water, and 

 mineral matter for the manufacture of food. These raw materials 

 are in the form of gases and solutions and enter through the cell 

 membrane. They remain in the vacuoles until they are needed. 

 Oxygen, also, is taken in during the breathing process. The 

 process by which material passes through a cell membrane is called 

 osmosis or absorption. Many theories are advanced to explain 

 this activity ; but probably no-one theory holds under all condi- 

 tions. According to one explanation there are minute openings in 

 the membrane through which the liquid or gas passes. 



34 



