4 PHILIPPINE AGRICULTURE 



How Plants make Food. It is only in the light that 

 plants are able to use carbon dioxid as a food. Car- 

 bon is taken from the air by the leaves. The leaves 

 contain a green substance called chlorophyll. It is be- 

 cause they have this green substance that plants can 

 use the carbon dioxid as a food. This chlorophyll ab- 

 sorbs the light. By means of the light which is ab- 

 sorbed by the chlorophyll, the carbon dioxid in the 

 leaves is united with the water taken up by the roots, 

 and forms sugar, which is a plant food. 



How Plants differ from Animals. You have learned 

 that plants, like animals, are living things. You have 

 also found out that typical plants differ from animals. 

 They differ in four important respects : 



1. Plants are green, containing a green pigment, or 

 color-body, chlorophyll, which is not found in animals. 



2. By means of chlorophyll, plants absorb the sun- 

 light, and by means of the light, they can make or- 

 ganic food, such as sugar, from the inorganic sub- 

 stances, carbon dioxid and water. 



3. Since these very simple food substances, carbon 

 dioxid and water, are almost everywhere in the world, 

 plants need not move to get their food. Therefore, 

 plants are stationary. 



4. Since plants are stationary, they can protect 

 themselves with rigid cell walls. These are made of 

 cellulose. Since animals must move to get their food, 

 they can have no such rigid cell walls. 



There are many plants which are not typical. Mush- 



