126 Liviiig Things Are Basically Alike unit ii 



Hugo von Mohl ( 1 805-1872) applied the these studies have shown the truth of the 



name protoplasm (first substance) to the cell theory which states that: 



living matter within the cell. Several years i . Plants and animals are made of cells 



later an English biologist, Thomas Henry and materials produced by cells. 



Huxley (1825-1895), made popular the 2. All the activities of living things are 



statement that protoplasm is "the physi- made possible by the activities of cells, 

 cal basis of life," w hich sums up the idea The evidence for this is now so com- 



that wherever there is life there is the plete that we no longer speak of this as 



substance protoplasm. Biologists of every the cell theory. These facts have been 



country have contributed to our under- so well established that it is better to 



standing of the cell and protoplasm. All speak of the cell doctrine. 



Questions 



1. Which activities distinguish the living from the lifeless? 



2. What are some of the activities of the cells of your body? 



3. Define oxidation. What kind of substances are formed as the result 

 of oxidation? Give three examples. Use the words oxidation and 

 burning in a sentence to show that you understand their meanings. 

 What, besides oxides, is released in all oxidation? Whei'e in living 

 things docs oxidation go on? Which substances usually are oxidized in 

 a cell? 



4. What is energy? What two kinds of energy are released in burning? 

 What is chemical energy and how does it differ from heat and light? 

 Give examples of changes of one kind of energy into another. 



5. What energy change occurs when oxidation takes place in a cell? 



6. Give examples of work done by your body; by a plant. 



7. What two kinds of substances must enter a cell if oxidation is to 

 continue at all times? By what process do they enter? 



8. Give an example of the diffusion of liquids and explain how they 

 diffuse. Describe an experiment in which you can see that diffusion is 

 occurring. 



9. Do liquids diffuse through a membrane which has no visible pores? 

 Describe an experiment which answers this question. 



10. Describe an experiment which shows that diffusion occurs through 

 the living cell membrane. 



11. What is the connection between solubility and the abiHt\' to diffuse 

 through a living membrane? Define the word permeable. What can 

 you say about the permeability of a living cell membrane? Name 

 three compounds that do not pass through a cell membrane. What 

 must happen to them before they can diffuse through a membrane? 



12. Name and define ten cell activities. 



13. What are the two parts of the cell theory? Give in order the names 

 and the contrii)utions of the biologists associated with the cell theory. 

 Why is it better to speak of the cell theory as the cell doctrine? 



