476 Introduction to the Study of Science 



root hairs aid in dissolving the soil? 24. (a) Describe root hairs. 

 (6) Why is dirt generally found clinging to roots? 25. Give some 

 practical suggestions for transplanting. Tell in each case enough of 

 the structure or function of the parts of a plant to make your sugges- 

 tion seem reasonable. 



26. How can you demonstrate the fact of transpiration from leaves ? 

 27. About how many pounds of water are used in the production by 

 the plant of one pound of dry substance? 28. (a) State some facts 

 to show the high percentage of water in garden and farm products. 

 (6) Which of the crops cited in the table, page 464, requires the largest 

 amount of water? Which the least? 29. In what way is the size of 

 leaves and their abundance related to the amount of water transpired ? 

 30. What relations do you note between leaves and sunlight ? 



31. Where there is too much water in the soil, what method is used 

 to dispose of it? 32. Where there is too little annual rainfall, what 

 two methods are used to bring crops to maturity? 33. (a) Under 

 what conditions is there a downward movement of water in the soil? 

 (6) An upward movement? 34. Distinguish between free water and 

 soil water. 35. Mention several illustrations of capillary action. 

 36. What is the general relation between the size of the bore of a 

 tube and the height to which capillary water will rise in it? 37. In 

 what kind of soil, fine or coarse, is the capillary action most marked ? 

 38. Explain why a newly sown field is sometimes rolled and later 

 cultivated. 39. How may a farmer conserve water in the soil for a 

 year or more? 40. Why does cultivation of the surface conserve 

 moisture ? 



41. Compare coarse and fine soils as to the amount of air contained 

 and the amount of circulation permitted. 42. About what part by 

 volume of the soil is air? 43. How can the amount of air in a sample 

 of soil be determined? 44. (a) How is a plant affected when its 

 roots are deprived of air? (6) How do you explain the apparent 

 exceptions? 45. Show how animals, plants, and frost may have a 

 part in soil aeration. 46. What is the value of the air to microscopic 

 organisms living in the soil? 47. In what way do legumes depend 

 on bacteria? 48. How is the dead plant and animal matter in the soil 

 changed into plant food? 49. (a) Under what conditions do nitrify- 

 ing bacteria become inactive and denitrifying become active ? (6) How 

 does the appearance of the plants indicate the change ? 



50. What facts should one know in order to make the best use of 

 soil in growing crops? 51. Compare the general temperature of the 

 soil with that of the air above it. 52. Mention some conditions that 

 control or determine soil temperature. 53. In what simple way can 



