Exam.,9th Sci, Chap. 8, Useful and Harmful Microbes.🎷

Class: 9

Subject:  Science & Tecnology 

Chapter 8: Useful and Harmful Microbes  

Q1. Fill in the blanks:

1. The process of conversion of lactose sugar in milk into lactic acid by lactobacilli is called ________.  
2. The antibiotic penicillin is obtained from a fungus called ________.  
3. Rhizobia living in root nodules supply ________ to leguminous plants.  
4. The National Institute of Virology (NIV) was established in 1952 in ________.  
5. The bacterium responsible for food poisoning in adverse anaerobic conditions is ________.  

Q2. Match the following:

Column 'A' (Microbe / Term).   Column 'B' (Role / Characteristic)

1. Lactobacilli        a. Nitrogen fixation in root nodules

2. Rhizobium         b. Production of yoghurt and buttermilk

3. Yeast.                   c. Fermentation for alcohol and bread making

4. Clostridium.      d. Food poisoning in adverse anaerobic conditions

Q3. State whether True or False:

1. Lactobacilli are aerobic bacteria that require oxygen to produce energy.  
2. Alexander Fleming discovered penicillin on 3 September 1928.  
3. All micro-organisms found in nature are harmful to humans.  
4. Alcanivorax bacteria are used to clean oil spills in oceans.  

Q4. Find the correlation:

1. Malaria : Protozoa :: Pneumonia : ________  
2. Lactobacilli : Yoghurt :: Saccharomyces : ________  
3. Penicillin : Antibiotic :: Alcanivorax : ________  

Q5. Answer in one sentence:

1. What are antibiotics?  
2. What is meant by symbiosis?  
3. What is 'rhizobial inoculation'?  
4. Which microbe is used for the absorption of the pollutant arsenic?  

Q6. Give scientific reasons:

1. Doctors advise taking yoghurt or buttermilk in case of indigestion or abdominal discomfort.  
2. Bread becomes spongy, soft, and easy to digest, whereas chapattis made from wheat only swell up.  
3. Salt is applied on the inner surface of pickle jars and the pickle is covered with oil.  

Q7. Mode of infection:

Identify the mode of infection for the following diseases based on the pathogen type:

1. Malaria (Pathogen: Protozoa): ________  
2. AIDS (Pathogen: Virus): ________  
3. Cholera (Pathogen: Bacteria): ________  
4. Dengue (Pathogen: Virus): ________  

Q8. Prevention of infection:

State the preventive measures for:

1. Pneumonia:  
2. Hepatitis:  
3. Dandruff, ringworm, and scabies:  
4. Bird Flu / Swine Flu:  

Q9.  Descriptive questions:

• What precautions must be taken while consuming and handling antibiotics?

  Or

• Write a short note on Clostridium bacteria and how they cause food poisoning.