Chapter 2 Class 8th Micro-organism : Friend or Foe

Microorganisms: Friend and Foe - Exercises

1. Fill in the blanks

(a) Microorganisms can be seen with the help of a microscope.

(b) Blue green algae fix nitrogen directly from air and enhance fertility of soil.

(c) Alcohol is produced with the help of yeast.

(d) Cholera is caused by bacteria.

2. Tick the correct answer

(a) Yeast is used in the production of (ii) alcohol

(b) The following is an antibiotic (ii) Streptomycin

(c) Carrier of malaria-causing protozoan is (i) female Anopheles mosquito

(d) The most common carrier of communicable diseases is (ii) housefly

(e) The bread or idli dough rises because of (iii) growth of yeast cells

(f) The process of conversion of sugar into alcohol is called (iii) fermentation

3. Match the organisms in Column A with their action in Column B

  • Bacteria - Producing antibodies
  • Rhizobium - Fixing nitrogen
  • Lactobacillus - Setting of curd
  • Yeast - Baking of bread
  • A protozoan - Causing malaria
  • A virus - Causing AIDS

4. Can microorganisms be seen with the naked eye?

No, microorganisms are too tiny to be seen with the naked eye. They can be seen only with a microscope.

5. What are the major groups of microorganisms?

  • Bacteria
  • Fungi
  • Protozoa
  • Algae
  • Viruses

6. Name the microorganisms which can fix atmospheric nitrogen in the soil.

Rhizobium, Nostoc, and Anabaena are nitrogen-fixing microorganisms that help increase soil fertility.

7. Write 10 lines on the usefulness of microorganisms in our lives

  • Making curd and cheese
  • Fermentation of food
  • Baking bread
  • Producing alcohol
  • Making antibiotics
  • Fixing nitrogen
  • Cleaning the environment
  • Decomposing dead matter
  • Producing vaccines
  • Used in biotechnology industries

8. Write a short paragraph on the harmful effects of microorganisms

Some microorganisms cause diseases like malaria and cholera. They spoil food, cause food poisoning, and damage crops. Houseflies and mosquitoes spread harmful microbes.

9. What are antibiotics? What precautions must be taken while taking antibiotics?

Antibiotics are medicines that kill harmful bacteria. Precautions include:

  • Take only on doctor’s advice
  • Complete the full dose
  • Never misuse or overuse
  • Don’t use for viral infections

Comments

Post a Comment

Popular posts from this blog

Class 6th Chapter 8 A Journey Through States of Water

A Journey Through States of Water - Class 6th 📚 A Journey Through States of Water - Class 6th 💧 Question 1 Which option below best explains the process known as condensation? Option Description (i) The conversion of water into its vapour state. (ii) The process of water changing from a liquid into gaseous state. (iii) The formation of clouds from tiny water droplets. (iv) The conversion of water v...
Read more

Chapter 3: Mindful Eating: A Path to a Healthy Body

Mindful Eating – Class 6 Class 6 Science – Chapter 3: Mindful Eating: A Path to a Healthy Body 1. Pick the odd one out and give reasons: (i) Jowar, Bajra, Ragi, Chana (ii) Kidney beans, Green gram, Soya bean, Rice (i) The odd one out is Chana . Jowar, Bajra, and Ragi are types of millets . Chana is a type of pulse . (ii) The odd one out is Rice . Kidney beans, Green gram, and Soya bean are types of pulses (plant protein sources). Rice is a cereal (carbohydrate source). 2. Discuss traditional versus modern culinary practices in India. Traditional cooking often used a chulha (stove) and ground ingredients using a sil-batta . Modern cooking commonly uses a gas stove and an electrical grinder . Changes are due to technology. 3. A teacher says that good food may act as medicine. Ravi is curious about this statement and has some questions for his teacher. List at least two questions that he can ask. ...
Read more

Class 6th Chapter 1 The Wonderful World of Science

Class 6 Science – Practice Questions Class 6 Science – Practice Questions Multiple Choice Questions (MCQs) 1. What is science primarily a way of doing? a) Memorizing facts b) Thinking, observing, and experimenting c) Reading stories d) Playing games ✅ Answer: b) Thinking, observing, and experimenting 2. Which of the following is listed as a main component of air in the sources? a) Hydrogen (Not in source) b) Helium (Not in source) c) Oxygen d) Methane (Not in source) ✅ Answer: c) Oxygen 3. What is an object called that can produce a magnetic field and attract unlike poles? a) Electric motor (Not in source) b) Compass (Not in source) c) Magnet d) Battery (Not in source) ✅ Answer: c) Magnet Very Short Answe...
Read more