92 



OUR FOOD SUPPLY 



No. 375. The Care of Food in the Home 



No. 413. Care of Milk and Use in the Home 



No. 841. Drying Fruits and Vegetables in the Home 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. The values of cooking food. 



2. An understanding of the conditions which cause 

 food to spoil. 



3. A knowledge of the various methods used to pre- 

 serve food. 



4. A knowledge of how foods are adulterated and 

 how adulteration affects the consumer. 



TEST OF MASTERY OF THE TOPIC 

 In your notebook complete the statements, answer the 

 questions, and comply with the instructions. 



1. State three reasons for cooking food. 



2. Heating milk at a temperature of about for a 



period of thirty minutes and then cooling it is called _ 



3. What is the most satisfactory method of safeguarding 

 milk from disease germs? 



4. State five methods used to preserve foods. 



5. Three plant organisms that cause food to spoil are 



6. Milk is caused to sour by 



7. Drying keeps some foods from spoiling because bac- 

 teria need 



8. Heat will bacteria. 



9. Sunlight will bacteria. 



10. Canning makes use of the fact that bacteria are . 



ir ( 



11. Milk is an excellent food because it 



12. The temperature in a refrigerator should be below 

 . degrees Fahrenheit. 



by 



13. What are the three types of bacteria? 



14. Ice in a refrigerator may be kept from melting by 

 wrapping it in newspaper. What do you think of this in 

 regard to the effective preservation of food in a refrigera- 

 tor? 



15. Dry ice is It is prepared by letting expand. 



This heat and therefore the turns to a state 



because its temperature is 



16. Dry ice is degrees colder than ordinary ice. 



17. Tell how you believe the Pure Food and Drug Act 

 could be improved. 



TOPIC 4. HOW THE HUMAN BODY USES FOOD 



SUGGESTED PROBLEMS AND QUESTIONS 



1. How is our food digested? 



2. How is digested food absorbed? 



3. How is food circulated in the body? 



a. How is blood forced through the body? 



b. Of what is blood composed? 



c. What are the functions of arteries, veins, 

 and capillaries? 



4. How is energy released to the body? 



SUGGESTIONS AND HELPS FOR STUDY 



1. You can obtain from this and other general sci- 

 ence textbooks all the information that you need to 

 solve the problems above. 



2. Keep in mind when you are studying the diges- 

 tive, circulatory, and respiratory systems that they all 

 work together to keep our bodies well nourished and 

 to release a sufficient amount of energy. 



3. As you read your textbook be sure to examine 

 and study very carefully the pictures and drawings 

 of the organs which make up the various systems that 

 you are studying. 



4. The following words may be new and difficult 

 for you. Study them carefully and use them often. 

 gland an organ which makes a special kind of body 



fluid ; e.g., the salivary glands in the mouth, which 

 make saliva. 



corpuscle a small body in the blood. There are red and 

 white corpuscles. 



haemoglobin the red protein in the red corpuscles. 

 assimilate to take in. 



artery a blood vessel which conveys blood from the 

 heart. 



EXPERIMENTS OR DEMONSTRATIONS WHICH WILL 

 HELP ANSWER THE PROBLEM QUESTIONS 1 



Experiment 63. What does saliva do to starch? 



Boil a small amount of starch in a test tube. Add some 

 saliva to the starch, shake it well, and let it stand thirty 

 minutes. Add Benedict's solution and heat. As a check on 

 the experiment add Benedict's solution to some boiled starch 

 in a test tube to which no saliva has been added, and heat. 



If you have time, repeat the experiment, using unsweet- 

 ened cracker in place of starch. What happened? 



In your notebook 1 complete the following statements and 

 answer the question. 



Benedict's solution is used to test for In the test 



tube containing starch and saliva, the color of the Benedict's 



solution changed to This showed that saliva changes 



starch to . 



Experiment 64. What digestion takes place in the 

 stomach? 



Obtain some pepsin at your local drug store or from a 

 dealer in biological supplies. Mince the white of a boiled 

 egg very fine. Place small quantities of the egg in four test 

 tubes. Label the tubes A, B, C, D. In test tube A, add some 

 pepsin solution and mix thoroughly. In test tube B, add 

 some pepsin solution and about two drops of sodium hy- 

 droxide solution and mix thoroughly. In test tube C, add 

 some pepsin solution and one drop of dilute hydrochloric 

 acid. Mix well. In test tube D, add pepsin solution and sev- 

 eral drops of dilute hydrochloric acid. Mix well. 



Allow the four test tubes to stand in a warm place for 



1 See workbook, p. 34. 



