SURVEY QUESTIONS 



Do you know how plants are helpful or harmful to one another ? What 

 is a balanced aquarium? What is an oxygen cycle? A carbon cycle? 

 What do you understand by symbiosis? What are parasites? What 

 factors caused the type of vegetation shown in this desert in Arizona ? 



Photo by Frank M. Wheat 



UNIT IX 



WHAT EFFECTS HAVE THE SURROUNDINGS ON THE 

 LIVES OF PLANTS AND ANIMALS? 



Preview. If bees, in their search for nectar, visited the flowers 

 of an apple tree, they would make possible the development of 

 apples on this tree. This development might be hindered by 

 other insects which prey upon ripening fruit, in which case man 

 may step in, and with a poisonous spray kill the insects and thus 

 save the fruit. 



But how did the bees benefit by this visit? They obtained 

 nectar to make into honey, and pollen to make into bee bread 

 for feeding the young. These will in turn replenish the hive the 



280 



i 



