1. Define communicable diseases. Give three examples.

2. Give two examples of each of the following types of microorganisms: a) Algae b) Fungi c) Protozoa.

3. What is pasteurization?

4. Mention any three ways through which pathogens are transmitted.

5. It is always suggested that not to eat anything from street hawkers. Why?

6. Ria thought of making curd. For this, she took lukewarm milk, mixed some curd into it and stir well. She kept the mixture in fridge. Next day she observed that curd was not set. Can you tell why the curd did not set?

7. Seema got cough and cold badly. Her teacher asked her to take rest at home and use handkerchief while sneezing and coughing. She obeyed her teacher.
a) Why should we keep a handkerchief on nose and mouth while sneezing or coughing?
b) What are the modes of transfer of diseases from infected to healthy person?
c) Do you think Seema’s teacher’s decision was right? Why?
d) What value of Seema is shown here?

8. Classify bacteria on the basis of their shapes.

9. Why are viruses considered to be the borderline between living and the non- living?
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