LOSS OF WATER 257 



QUESTIONS AND PROBLEMS 



1. Where in the leaf does the actual loss of water occur? 



2. Why does not the air in the intercellular spaces become saturated with 

 water vapor and stop transpiration? 



3. Is there any connection between water loss and the amount of water 

 absorbed from the soil? What proportion absorbed is evaporated? 



4. What would be the effect, if any, of growing a plant continuously 

 in a saturated atmosphere? 



5. Why do florists often water the walls and walks of greenhouses as well 

 as the plants? 



6. Why are wilted plants inefficient? 



7. Is it possible for a plant to wilt in an abundant water supply? Explain. 



8. Why do wilted plants generally revive at night even when there has 

 been no precipitation? 



9. Deciduous trees are sometimes called "seasonal xerophytes." Why? 



10. If the water requirement of corn is 500 and if a dry corn plant weighs 

 200 grams, how deep a layer on the surface of a cornfield would the transpired 

 water make if three plants are planted in each hill and the hills are a meter 

 apart? 



11. The Roman Campagna was planted with sunflowers to prevent the 

 spread of malaria. Why? 



12. In Australia it was once proposed to import "rain trees" (with high 

 guttation) for irrigation purposes. Discuss the feasibility of this method of 

 increasing the water supply. 



13. Before a storm the barometer falls. Reconcile this with the relation be- 

 tween pressure and transpiration as discussed in the text. 



14. What is xeromorphism? 



15. Does the pH of the guard cells increase or decrease during photosyn- 

 thesis? 



16. What may be the relation between evaporation and fruit decline in 

 lemons? 



17. Does the rolling of the corn leaf check transpiration? Which way does 

 it roll? Where are the stomata located? 



18. Would you expect more or less transpiration on a peat soil than on a 

 rich loam soil? 



19. Leaves generally have a higher osmotic pressure than other organs of 

 the plant. Give two possible reasons for this. 



20. In general the osmotic pressure of plant cells varies inversely with the 

 humidity. Why? 



21. Evergreen shrubs and trees frequently show a higher osmotic pressure 

 in the cells of their leaves in winter than in summer. Explain. 



22. Although alfalfa has a high water requirement, it thrives in the plains 

 regions where water is not very plentiful. Explain. 



