FOODS IN PLANTS 55 
9. Can you arrange an apparatus to test the pressure with which 
maple sap flows from a cut branch? 
10. Can you explain the fact that you cannot get seed from beets 
and carrots the same year that the plants are grown from the seed? 
11. It is often stated that one difference between plants and animals 
is that plants use carbon dioxide and throw off oxygen, and animals use 
oxygen and throw off carbon dioxide. In what ways is this statement 
correct and in what ways is it an error? 
12. In what sense is it true that the sun is the source of the energy 
by means of which plants and animals do their work? 
13. In what ways is it important to your community that the people 
should know something about photosynthesis ? 
