Deserts 



99 



QUESTIONS FOR REVIEW 



1. Do leaves absorb moisture? 



2. What makes them revive under rain or dew? 



3. Illustrate the rate at which water travels from root 

 to leaf. 



4. Describe the peculiar qualities of the ice -plant, the 

 grasses of the Kalahari Desert, the mesquite and the prickly- 

 pear. 



5. What other plants are utilized in desert regions? 



6. What reasons show that evaporation is not the cause of 

 the coolness of these fruits? 



7. What does this teach as to the temperature of living 

 plants? 



8. What reasons point to vegetation as one cause of rain? 



9. In what different ways does vegetation help to preserve 

 the moisture of a region? 



10. Illustrate this in the case of St. Helena and of Northern 

 Egypt. 



11. Describe the effect of the rising of the Atbara in Nubia. 



