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BIOLOGY AND HUMAN LIFE 



2. Osmosis 



Meaning of osmosis 

 Osmosis in living things 

 Into cells ; out of cells ; 



3. Absorption in organisms 



Root absorption 

 Materials 

 Organ 

 Relation to life of plant 



within cells 



Absorption in one-celled organisms 

 What is taken in 

 How material is taken in 



Absorption in larger animals 

 Digestion 



Character of change 



Importance to living things 



Leaf absorption 



Where it takes place 

 What is absorbed 

 Relation of absorbed 

 material to life of plant 



Relation of intake to life 



How brought about 

 Enzyms ; ferments 



QUESTIONS 



1. What practical use do we sometimes make of the fact that gases 

 diffuse readily ? 



2. What would be the condition of our atmosphere if the different 

 gases in it did not diffuse ? 



3. What substances swell in water without dissolving ? 



4. Why will ink spread on wet paper but not on dry ? 



5. Why does the protoplasm inside a cell shrivel or shrink up when 

 the cell is placed in salt water ? 



6. Will a root or a sausage shrink or swell in salt water ? Why ? 



7. Under what conditions will a cell absorb more than it gives out ? 



8. Under what conditions will a cell give out more than it absorbs ? 



9. How can animals make use of solid food ? How can plants ? 



REFERENCE READINGS 



Bergen and Caldwell. Practical Botany, pp. 7-9. 

 OsTERHOUT, W. J. V. Experiments with Plants, pp. 1 21-124. 

 Densmore, H. D. General Botany, pp. 137-142. 



Fabre, J. The Glowworm's Anaesthetic (extract in C. H. Ward's 

 "Exploring Nature," pp. 101-107). 



