248 A YEAR IN SCIENCE 



Questions 



1. Name ten plants of economic value. 



2. In what way is each of these plants useful to 

 man? 



3. What is the name of the group of plants which 

 include those most harmful to man? 



4. Give three examples of plants belonging to this 

 group. 



5. Define parasite, saprophyte, and host. 



6. Where are bacteria found ? What is their size ? 

 How do they multiply? 



7. What conditions are most favorable to the 

 growth of bacteria? 



8. When is a substance said to be sterilized? 



9. Is there any advantage in having plenty of sun- 

 shine in our houses? 



10. Name diseases which are produced by bacteria. 



11. W T hat are infectious diseases? 



12. Why is it important to know whether or not a 

 disease is infectious? 



13. Discuss the relation of bacteria to decay. 



14. State the ways in which decay is of value to 

 man. 



15. What are the chief methods used to preserve 

 our foods? 



16. What are the objections to the vise of preserva- 

 tives in foods? 



17. Discuss the ways in which bacteria are of 

 benefit to man. 



