22 THE NATURE AND NEEDS OF LIVING MATTER 



2. If nitrogen can be obtained from the air only by certain 

 plants, how must animals get it ? 



3. What part of the air is oxygen ? Nitrogen ? 



4. What are the most abundant elements in living 

 matter ? 



5. Where may carbon be found ? 



6. What results from the electrolysis of water ? 



7. Why does excluding air from a fire cause it to go out ? 



8. What is the object of a draft in furnaces ? 



9. Why does a blacksmith use a bellows in forcing air 

 (oxygen) into the fire ? 



10. Why do we breathe more rapidly when we run or work 

 hard? 



11. Try to explain what happens when you strike a match. 

 Note. The head of the match contains phosphorus, sul- 

 phur, etc. 



12. What method did the savages formerly use in starting a 

 fire ? Explain. 



13. If oxidation also produces energy, or the ability to do 

 work, where does the energy of the locomotive come from ? 

 Of the body ? 



14. How is the body supplied with fresh portions of 

 carbon? 



15. How would you test for the presence of carbon 

 dioxide ? 



16. Sum up as many results of oxidation as you can. 



Special Reports 1 



1. The importance of water to living things. 



2. The manufacture of charcoal and illuminating gas. 



3. The chemical elements in the body. 



1 Instead of having such reports always read in class, let the pupil give a talk 

 on his chosen topic. Such talks should, of course, be carefully thought over 

 beforehand. This gives very good practice in oral presentation. Optionally, 

 written reports may be handed in at times. 



