Concepts of Biology (BIOL115) - Dr. S.G. Saupe (; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321

Photosynthesis � Classic Experiments

 Jean Baptista van Helmont (1577 � 1644)
    van Helmont performed an experiment in which he placed a willow seedling in a sealed pot.  He watered the plant regularly.  The plant weighed five pounds at the beginning of the experiment and 169 pounds at the conclusion of the experiment five years later.  The primary source of the increased weight (mass) of the plant is from:

a.  the water he added
b.  minerals that were present in the soil
c.  carbon dioxide in the air


 Joseph Priestly (1733 � 1804)
    Priestly was a Unitarian minister and chemist.  He did the following experiments:



  1. Why did the candle burn out when placed under bell jar?

  2. Why could the candle be relit after allowing it growth with a mint plant?

  3. Why does a mouse die when it is placed under a bell jar?

  4. Why was the mouse able to survive when placed in the jar with a mint plant?

  5. Assuming a supply of water was available to both mint plant and mouse; could the mouse and plant survive indefinitely under the jar?  Explain.


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Last updated: October 22, 2004
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