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  1. What part of a plant leaf enables gas exchange and regulates water loss?
  2. Why is chlorophyll a so efficient? 
  3. What are three ways that water can travel in a plant?


  1. Mesophyll cells
  2. Chlorophyll a has alternating single and double bonds.
  3. There are three ways water travels.  The first way is transpiration.  This is also known as the cohesion theory.  This is controlled by the stomata.  It is the attraction between molecules of water.  The second way water can travel against the flow of gravity is by root pressure.  This occurs when the stomata is closed, usually at night.  Both water and pressure build up.  The third way is capillary action.  This is also called adhesion.  It is the ability of water to cling to other things.  The water travels up a very thin tube.  The thinner the tube, the higher the water goes.