Fill in the blanks:
(1) Despite the absence of a heart or a circulatory system in plants the flow of water upward through the xylem in plants can achieve fairly high rates up to .....a.....metres per hour.
(2) Less than .....b...... Percent of the water reaching the leaves is used in photpsynthesis and plant growth.
(3) Water loss from a leaf can be studied by using ......c...... .
(4) Most researchers agree that water is mainly .....d..... through the plant.