TESTS 173 



Climbing stems, as a result of the stimulation of the sun, twist 

 around a support in a given direction, sometimes revolving with 

 and sometimes against the course of the sun. 



We also find stems and leaves modified to become holdfasts as 

 the tendrils found in climbing plants. Thorns, a protection from 

 animals, may be modified parts of leaves or of stems. 



Practical Exercise 12. Make a list of the modified stems found in your 

 locality. Show how each modification may be of use to the plant. 



Self-Testing Exekcise 



A modified stem is one that has probably been changed by the 



(1) in the (2) . Modified stems may be in the form 



of (3) as in the (4) . Some stems may be (5), 



while others may be (6), forming (7) . 



Review Summary 



Test your knowledge of the unit by (1) rechecking the survey questions; 



(2) performing all assigned exercises ; (3) checking with your teacher all tests 

 and making up all missed parts ; (4) making an outline of the unit for your 

 notebook. 



Test on Fundamental Concepts 



In a vertical column under the heading correct write numbers of all statements you believe 

 are true. In another column under incorrect write numbers of untrue statements. Your 

 grade = number of right answers X 2. 



I. Roots (1) grow toward water; (2) are affected by gravity; 



(3) may take carbon dioxide from the soil; (4) always store food; 

 (5) hold a plant firmly in the ground. 



II. A root is able to take in water (6) because it is made of woody 

 tissue ; (7) by means of osmosis ; (8) because it has a root cap covering 

 each tiny root ; (9) through minute root hairs ; (10) because it gives 

 off an acid. 



III. Roots are useful to plants because they (11) may store food; 

 (12) gtow against gravity; (13) absorb mineral matter from the soil; 

 (14) act as anchors ; (15) take in oxygen through their stomata. 



IV. The process by which food is made by green leaves is known as 



(16) transpiration; (17) protein-making; (18) nutrition; (19) photo- 

 synthesis ; (20) osmosis. 



