PHYSIOLOGICAL PROCESSES IN PLANTS 99 



Conclusions. 1. What gas is given off by green plants in 

 sunlight? 



2. What gas have we learned is used as a food by green 

 plants when they are in sunlight? 



3. What substances have we learned are manufactured in 

 the leaves? 



Note. The process of starch formation in green leaves by 

 aid of sunlight and chlorophyll is known as photosynthesis 

 (photo light, and synthesis a putting together). 



This process may be chemically expressed somewhat as 

 follows : energy (sunlight) -f- chlorophyll (assistant) 4- 6 C0 2 

 (carbon dioxide) + 5 H 2 (water) + ? H 2 = C 6 H 10 5 (starch) 

 + energy (stored up) + 12 (oxygen set free) + ? H 2 O (water 

 set free or transpired). This makes no pretense of being an 

 exact equation, as the processes of photosynthesis are not fully 

 understood. 



4. Does photosynthesis take place in fungi ? 



(1) STARCH (ANALYSIS AND SYNTHESIS) (OPTIONAL) 



Observations. 1. Put starch in a test tube and heat it. Conduct any 

 escaping gases by means of a bent glass or rubber tube to a small bottle 

 of limewater. What change in the color of the starch ? 



2. What collects on the sides of the tube ? Where must it have come 

 from? 



3. What change in the color of the limewater ? What gas given off ? 

 Note. The separation of a substance into its parts is known as 



analysis, while the putting together of its parts is known as synthesis. 



Conclusions. 1. Which process took place in the test tube ? In the 

 leaf? 



2. What two substances are found in starch ? 



(2) WHAT BECOMES OF THIS FOOD ? 



Observation. Select some healthy leaves growing in sun- 

 light that test shows contain starch. Pin circular disks of 

 cork on opposite sides of the leaf and after 24 hours test again 

 for starch. Results ? 



Note. Be sure to remove all the chlorophyll by changing the alcohol 

 BS many times as necessary. 



