124 BIOLOGY AND HUMAN LIFE 



5. Uses of leaves 



Direct 



As food As source of specific mate- 



As fodder for cattle rials in certain plants 



As humus and mulch 



Indirect 



Source of nearly all human food, and. in fact, of nearly all 

 organic matter that we use, including our own bodies 



6. Uses of roots 



As food and fodder ; specific drugs etc. ; propagation 



7. Uses of stems 



As food (potato, sugar For drugs, gums, resins,. 



cane, sago, etc.) dyes, tanning material 



For fibers For wood and cork 



8. Food-making in simple plants 



Essential organs (chlorophyl organs) 

 Sources of material 



Water ; carbon dioxid ; (salts) 

 How materials are obtained 

 Q. Our dependence upon sunshine 



QUESTIONS 



1. In what sense does Hfe depend upon the destruction of (the living 

 being's own) protoplasm ? 



2. In what sense does life depend upon destruction of other living 

 things ? 



3. How can life be destroyed without making for more life ? 



4. What are the inorganic materials from which carbohydrates origi- 

 nate ? What is the source of each ? 



5. How can we show that fight is necessary for photosynthesis? 



6. How can we show that carbon dioxid is essential to photosynthesis ? 



7. How can we show that oxygen is given off during photosynthesis ? 



8. How do mushrooms and other non-green plants get their food ? 



9. What organic materials in a plant or animal are not produced by 

 photosynthesis ? 



10. What organic substances are there in your body (or in any other 

 organism) that are not nutrients ? 



