QUESTIONS 



33 



IX. Draw a complete cell of SpirogjTa as observed under the high-power 

 objective. Label filament sheath, cell wall, strands of cytoplasm, plasma 

 membrane, vacuole, nucleus, nucleolus, spiral chloroplast, and pyrenoid. 



X. Write a description of Spirogyra, mentioning all the parts that you saw. 



The simplest plants have no root, stem, 

 nor leaves. Such plants are called Thal- 

 lophyta {thallus — shoot ; phyton — plant) . 

 The green thallophytes are called algae. 

 Their color is due to the presence of chloro- 

 plasts that vary in size and shape. The 

 algae that we have already studied are 

 Pleurococcus and Spirogyra. Other thal- 

 lophytes lack chloroplasts and are usually 



colorless. They are called fungi. Yeasts and molds are common 

 examples of fungi. 



Pleurococcus is found as single 

 plants or in groups. 



Questions 



1. Outline in tabular form, the names of the scientists, their nation- 

 alities, century in which they worked, and their contributions to the 

 cell theory. 



2. Draw as many labeled cells as are necessary to show cell wall, 

 nucleus, cytoplasm, vacuole, pyrenoid, and chloroplast. 



3. Compare Spirogyra with another alga that you have studied. 



4. What makes Spirogyra slimy ? 



5. What is a reason for the name thallophytes ? 



Supplementary Reading 



Gager, C. S., General Botany (P. Blakiston's Son & Co.), chap. ii. 



Haupt, A. W., Fundamentals of Biology, (McGraw-Hill Book Co. Inc.), 



chap. iv. 

 Holman, L. A., and Robins, W. W., Textbook of General Botany (John Wiley & 



Sons). 

 Holmes, S. J., General Biology (Harcourt, Brace & Co.), chap. iii. 



