1 62 All Food Is Made by Green Plants unit hi 



settled. Describe. Does anything float? If so, what is it? Use a hand lens 

 to examine the smaller particles. 



3. Does ordinary soil contain air? Pour water into a large battery jar 

 until it is half full. Put a trowel full of soil at the bottom of the jar. 

 Watch. Explain. 



4. How does soil water differ from pure water? Soak soil in a flower- 

 pot so that there is more water than the soil can hold. Let it stand for an 

 hour. By pressing the soil, pour off the extra water into a funnel lined 

 with a fine cloth. Collect the water that drips through. How does the 

 water Icjok? If it is not clear, filter it again through filter paper. Boil this 

 water in an evaporating dish until the water is evaporated. Does anything 

 remain? 



5. To see root hairs, lay six mustard or radish seeds (peas or corn may 

 be used but will grow much more slowly) on moist blotting paper in a 

 saucer. Cover with a glass plate. Do not allow the blotting paper to dry. 

 Examine the roots everv^ day with a magnifying glass. Do not touch them. 

 Why? Record your observations. Root hairs will also grow on the new 

 roots of a Tradescantia cutting placed in a test tube of water. 



6. You can learn something about root structure from a carrot. If 

 possible use young carrots with fresh stems and leaves. After cutting off 

 the tips of the roots place the carrots in a tumbler containing red ink in 

 water. After standing in the bright light for several hours one of the 

 carrots should be sectioned at various levels. Make a longitudinal section 

 through a second. Draw, indicating by means of red crayon, the regions 

 where water rises in the root. Compare with the diagram of the root in 

 the text. How does it differ? On your drawing label vascular cylinder, 

 cortex, epidermis, water tubes. In \\hich region do the stored carbo- 

 hydrates lie? How can you find out? 



7. What is the structure of a young root? Gather some young fibrous 

 roots about tit inch in diameter. Scrape these with the fingernail. How 

 does this substance feel? What is left when you have removed this sub- 

 stance? What could you call the part that is left? Try to break it and 

 to tear it. What do you notice? Explain. 



8. In woody dicot stems the tissues are in cylinders. You can easily see 

 the ends of these cylinders if you make a clean cut across the end of a 

 twig with a sharp knife or razor blade. Note the soft pith at the very 

 center. Which cylinder is outside the pith? Feel its inner and outer part. 

 Describe. The cambium lies between the two parts. Why do you not see 

 it? Outside the phloem in some twigs there is a ring of hard tissue, the 

 fibers, and farther out lying just inside the brown cork is the cortex 

 composed of soft tissue. If the twig is young enough you may be able 

 to see the transparent epidermis. 



9. How much does a stem grow in length in one year? Examine a twig 

 which is not in leaf. Measure it from the large terminal bud to the first 

 circular scar on the twig. This scar marks the point where the season's 



