** This activity has been modified from an activity originally posted by Joe DiBari at Troy High School.

Problem:   How do you safely simulate the spread of an infectious disease?

Complete the following hypothesis …

Hypothesis:   If  one individual is given a simulated infection and allowed contact with other people, then ……

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Note:  You will be simulating the spread of a microbial disease by using water and a chemical whose presence in the water can be easily shown.

Materials:   distilled water, test tubes, unknown chemical, sodium chloride

Procedure:

1. Obtain a covered test tube of water. All the test tubes for the class have water in them. One of them appears to be water but there is a chemical dissolved in it.
2. Go around the room and exchange liquids from your test tube with three other people. To do this, pour one-third the volume of liquid in your test tube into the test tube of a classmate. Then that person should pour the same amount of liquid back into your test tube. These actions represent the transfer of microbes between persons.
3. Record the names of the persons with whom you interchange liquid in the order in which you made the exchanges.
4.  After you are finished with the exchanges, go to the instructor who will add a chemical to the liquid in your tube. If the liquid remains clear, then you are not infected. If a white cloudiness appears in the liquid, then you are infected.

** When you have finished your work, write a formal report on this lab.    This should follow accepted format and include a data table which lists the people initially infected and those infected in the lab when the lab was completed.   This report should also answer the discussion questions in its conclusion.

Your data table which you will construct should list the people you interacted with in this procedure and whether or not they had the disease.   Your teacher envisions a two column data table with a title!  J

Conclusion Questions:

1.  Who was the source of the infection?
2.  Describe briefly the process you used to trace the infection back to its source.
3.  List three steps can be taken to prevent infections from spreading?
4.  In this simulation, what represented the antigen?
5-6.  What type of cell fights infection in humans?  Name two types of these cells and explain how they fight infection.
7.  What are some possible sources of error in this investigation?

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In addition, complete the following questions relating to this lab activity which have appeared on previous Living Environment Regents Examinations

Base your answers to questions 1 and 2 on the table below and on your knowledge of biology.

1.  None of these volunteers ever had chicken pox. After the injection, there would most likely be antibodies to chicken pox in the bloodstream of   (1) volunteers A and D, only    (2) volunteers A, B, and D   (3) volunteer C     (4) volunteer D, only

2.  Volunteers A, B, and D underwent a procedure known as  (1) cloning   (2) vaccination  (3) electrophoresis     
(4) chromatography

Base your answers to questions 3 and 4 on the diagram of a slide of normal human blood below and on your knowledge of biology.

3.  An increase in the production of the cells labeled A is a response to an internal environmental change. State a change that might cause this response.

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4.  Describe one possible immune response, other than an increase in number, that one of

the cells labeled A would carry out.

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5.         Identify the cell labeled X.

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6.         State one way a cell such as cell X helps to maintain homeostasis.

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9.  Microbes that enter the body, causing disease, are known as

(1) pathogens    (2) enzymes   (3) antibodies       (4) hosts

10.  Certain microbes, foreign tissues, and some cancerous cells can cause immune responses in the human body because all three contain

(1) antigens       (2) fats    (3) enzymes  (4) cytoplasm

11.  Which statement best describes what will most likely happen when an individual receives a vaccination  containing a weakened pathogen?

(1) The ability to fight disease will increase due to antibodies received from the pathogen.

(2) The ability to fight disease caused by the pathogen will increase due to antibody production.

(3) The ability to produce antibodies will decrease after the vaccination.

(4) The ability to resist most types of diseases will increase.

12.   The use of a vaccine to stimulate the immune system to act against a specific pathogen is valuable in maintaining homeostasis because
(1) once the body produces chemicals to combat one type of virus, it can more easily make antibiotics
(2) the body can digest the weakened microbes and use them as food
(3) the body will be able to fight invasions by the same type of microbe in the future
(4) the more the immune system is challenged, the better it performs