AIR AND SUNLIGHT 19 



4. What is said of carbon dioxide? 



5. What can you say of the relative amount of this substance ? 



6. Mention the natural sources of carbon dioxide. 



7. Explain how carbon dioxide may be prepared artificially and how its 

 presence may be detected. 



8. Through what means are the gases in the atmosphere kept evenly 

 distributed? 



9. Is the popular belief that plants inhale carbon dioxide and exhale 

 oxygen always true ? Explain. 



10. What effect has darkness and cloudy weather on the respiration of 

 plants ? 



11. In what forms is oxygen found in plants and animals? 



12. What effect has oxygen on the germination of seeds ? 



13. Discuss oxygen in its relations to young plants, young buds, flowers, 

 ind fruit. 



14. What plants inhale oxygen and exhale carbon dioxide? 



15. What can you say of the amount of oxygen present in vegetable 

 matter ? 



16. Discuss nitrogen and its relations to plants* 



17. What is said of hydrogen? 



18. Discuss air pressure. 



19. How is the earth kept warm? 



20. Discuss sunlight and its action on plants. 



21. What is chlorophyll? 



22. How is all plant food formed ? 



REFERENCES 



The Soil, King. 



Agriculture, Storer. 



Cyclopedia of A merican Agriculture, Bailev 



Chemistry, Wurtz. 



Physical Geography, Dryer. 



