Protoplasm, the Cell, and the Organism - 39 



be considered as an integral living unit. This 

 conclusion was confirmed by tissue culture 

 experiments, which were begun by Harrison 

 in 1912. 



5. The life of the whole organism rep- 



resents the sum total of the integrated life 

 of the component cells. This conclusion is 

 scarcely susceptible to proof, but is a view- 

 point supported by a wide variety of observa- 

 tions and experiments. 



TEST QUESTIONS 



1. List the features that are possessed by typical 10. 

 cells generally. Make a fully labeled sketch 



of any cell that displays all these features. 



2. Explain why each of the following is not to 



be regarded as a typical cell: (a) blue-gieen 11. 

 algae; (b) certain slime molds. Make labeled 

 sketches to illustrate the points in question. 



3. Cite examples (including the dimensions of): 12. 



a. an extremely small cell 



b. an extremely large cell 



c. a cell of average size 13. 



4. Explain how and why cells generally cannot 

 grow beyond a certain definite limit. 



5. Why do cells tend to assume a droplike form 14. 

 when constraining factors are absent? Ex- 

 plain. 



6. Cite two examples to illustrate the general 

 rule that the form of a cell is generally re- 

 lated to its function. 15. 



7. Distinguish between: 



a. chromatin and chromosomes 16. 



b. chromatin and chromidia 



c. chlorophyll and chloroplasts 



8. Cite evidence indicating that the chromatin 17. 

 part of the protoplasm is very essential in 

 every cell. 



9. Specify five kinds of cytoplasmic bodies and 

 explain how each is identified. 



Carefully identify each of the following: (a) 

 phase-contrast microscopy; (b) darkfield mi- 

 croscopy; (c) interference microscopy; (d) 

 electron microscopy. 



What properties of the plasma membrane 

 distinguish it from such extraneous mem- 

 branes as the pellicle and cell wall? 

 Describe the microinjection technique and 

 explain how it has been used to prove the 

 existence of the plasma membrane. 

 Define the terms "cell wall" and "pellicle"; 

 specify at least three differences between 

 these two kinds of membranes. 

 Cite an experiment that demonstrates the 

 general importance of the nucleus in the 

 metabolic activities of the cell. What other 

 evidence tends to substantiate the conclusion 

 drawn from the experiment? 

 Distinguish between an organ and an organ- 

 ism. 



Explain the technique of tissue culture; what 

 important conclusion has been derived from 

 tissue culture experiments? 

 Carefully identify each of the following 

 terms: (a) lysosomes; (b) chromosomes; (c) 

 ribosomes; (d) Golgi bodies; (e) mitochondria; 

 (f) nucleolus; (g) endoplasmic reticulum. 



FURTHER READINGS 



1. Unresting Cells, by R. W. Gerard; New York, 

 1949. 



2. General Cytology, 3d ed., by E. D. P. De- 

 Robertis, W. W. Nowinwski, and F. A. Saez; 

 Philadelphia, 1960. 



3. Great Experiments in Biology, Ed. by M. 



Gabriel and S. Fogel; Englewood Cliffs, N. J., 

 1955. 



The Cell, ed. by J. Brachet and A. E. Mirsky. 

 5 vols., New York, 1961. 

 "The Living Cell." special issue of Scientific 

 American, September 1961. 



