174 GREEN PLANTS AS FOOD MAKERS 



V. Green plants breathe through (21) lenticels; (22) root hairs; 

 (23) stomata; (24) guard cells; (25) epidermal cells. 



VI. Food in plants is made soluble by (26) water ; (27) enzymes ; 

 (28) the palisade layer of cells ; (29) oxygen ; (30) digestion. 



VII. A green plant (31) makes sugar; (32) gives off nitrogen; 

 (33) is a solar engine; (34) manufactures proteins and fats by a 

 process known as photosynthesis ; (35) gives off oxygen in sunlight. 



VIII. Dicotyledonous stems (36) grow from a thin layer called 

 cambium ; (37) show annual rings of growth ; (38) have a large area 

 of pith and a rind ; (39) pass foods downward through the sieve tubes 

 just outside the cambium ; (40) contain pith rays. 



IX. Monocotyledonous stems (41) have scattered fibrovascular 

 bundles; (42) grow by having these bundles arranged in a ring, 

 growth taking place from the cambium; (43) have a strong rind 

 formed of bundles and epidermis ; (44) contain medullary rays ; 

 (45) have annual rings. 



X. Stems (46) are pathways for food and water; (47) owe their 

 strength to the tough walls of the cells of which they are composed; 

 (48) might be called organs of circulation and support; (49) may be 

 modified into leaves; (50) may be modified into tendrils to help in 

 climbing. 



Achievement Test 



1. How can you devise an experiment that would show the amounts 

 of wa»ter which various soils can hold ? 



2. What are root hairs, where are they found, and what do they do ? 



3. How can you prove that root hairs give off an acid? 



4. How can you devise an experiment to illustrate the principle of 

 osmosis ? 



5. How can you show that the sun affects the direction of growth 

 of a green plant? 



6. How can you make a diagram to show the cell structure of a leaf ? 



7. How can you prove by experiment what factors are necessary for 

 sugar-making in a green plant ? 



8. What are the chief differences in the structure of monocoty- 

 ledonous and dicotyledonous stems? 



9. How can you prove that water or food passes up and down in a 

 stem? 



