14 CHAPTER 1 



1.9. Assume the genetic factor has a supernatural basis. Could we learn anything 

 about it b> the scientific method of investigation? Explain. 



l.K). Do you think human beings provide good material for the study of the genetic 

 factor? Explain. 



1. 11. What si/e limitations can you give to the genetic material? 



1.12. Is the existence o[ genetic material presumed or proved? Explain. 

 LI 3. What do the bean experiments reveal about genetic material? 



1.14. August Weismann ( 1834-1914) cut off the tails of mice for a series of genera- 

 tions and found that tail length remained normal each new generation. Why 

 are these experiments significant? 



1.15. What are the consequences of mitosis? 



1.16. For each of the properties of chromosomes listed in the Summary and Conclu- 

 sions, state the corresponding property of the genetic material and identify it as 

 one that is either proved or assumed. 



1.17. [f the chromosomes serve as the genetic material, each cell of the body derived 

 by mitosis should carry the same genotype. Describe how you would test this 

 idea, using a multicellular plant. 



1.18. What are the advantages or disadvantages of chromosome coiling? 



1.19. Can you imagine a spindle which is too small for normal cell division? Explain. 



1.20. Suppose certain nuclei normally do not divide with the aid of a spindle. How 

 would this affect your ideas about genetic material? 



1.21. Discuss the statement that all cell divisions are normally mitotic. 



1.22. Differentiate between replication of chromatids and of chromosomal material. 



1.23. List the events that presumably take place before a given telophase chromosome 

 can give rise to a chromosome made entirely of chromosomal material not yet 

 synthesized. 



1 .24. Why should the peas in a pod be similar? Different? 



1.25. What do each of the following observations mean with regard to the origin and/or 

 integrity of chromosomal material? 



(a) Nonhomologous chromosomes retain their characteristic morphological dif- 

 ferences mitosis after mitosis. 



(b) A loss or gain of one entire chromosome occurs occasionally, with all mitotic 

 descendants having the same aberration. 



(c) T. Boveri noted in Ascaris cleavage that sister cells entering the next mitosis 

 often have a mirror-image arrangement of their chromosomes. 



1.26. What conclusions can you draw from the fact that there are three genotypically 

 different kinds of Indian corn: one always has red kernels, one always has yellow 

 kernels, and one has kernels which are yellow but become red if exposed to 

 sunlight? 



