Chapter-2. The Invisible Living 2 World: Beyond Our Naked Eye Science Curiosity class 8 in english Medium CBSE Notes

MCQs – The Invisible Living World: Beyond Our Naked Eye

1. Microorganisms are organisms that are:

A. Very large
B. Visible to naked eye
C. Too small to be seen without a microscope
D. Only found in water

Answer: C. Too small to be seen without a microscope

2. Which of the following is a unicellular organism?

A. Mushroom
B. Amoeba
C. Fern
D. Rose

Answer: B. Amoeba

3. Bacteria have:

A. True nucleus
B. Nucleoid
C. Chloroplast
D. Cell wall only

Answer: B. Nucleoid

4. Fungi do not have:

A. Cell wall
B. Cell membrane
C. Chloroplast
D. Cytoplasm

Answer: C. Chloroplast

5. Microorganisms are found in:

A. Water only
B. Soil only
C. Air only
D. Everywhere

Answer: D. Everywhere

6. Which microorganism can make its own food?

A. Fungi
B. Algae
C. Bacteria
D. Virus

Answer: B. Algae

7. Yeast is a type of:

A. Bacteria
B. Fungi
C. Virus
D. Protozoa

Answer: B. Fungi

8. Which instrument is used to see microorganisms?

A. Telescope
B. Microscope
C. Periscope
D. Stethoscope

Answer: B. Microscope

9. Protozoa are:

A. Multicellular
B. Unicellular
C. Non-living
D. Plants

Answer: B. Unicellular

10. Which of the following is not a microorganism?

A. Bacteria
B. Algae
C. Tiger
D. Fungi

Answer: C. Tiger

11. Viruses can reproduce only:

A. In water
B. In air
C. Inside living cells
D. In soil

Answer: C. Inside living cells

12. Which of the following causes disease?

A. Useful bacteria
B. Harmful microorganisms
C. Plants
D. Sunlight

Answer: B. Harmful microorganisms

13. Lactobacillus helps in making:

A. Bread
B. Curd
C. Cheese only
D. Butter

Answer: B. Curd

14. Antibiotics are used to:

A. Kill harmful bacteria
B. Grow plants
C. Increase temperature
D. Make food

Answer: A. Kill harmful bacteria

15. Which microorganism is used in baking?

A. Amoeba
B. Yeast
C. Virus
D. Algae

Answer: B. Yeast

16. Microorganisms help in:

A. Decomposition
B. Pollution only
C. Drying clothes
D. Cutting wood

Answer: A. Decomposition

17. Which of the following is a harmful effect?

A. Making curd
B. Causing diseases
C. Decomposition
D. Nitrogen fixation

Answer: B. Causing diseases

18. Nitrogen fixation is done by:

A. Fungi
B. Bacteria
C. Virus
D. Animals

Answer: B. Bacteria

19. Algae are important because they:

A. Cause disease
B. Produce oxygen
C. Destroy soil
D. Reduce sunlight

Answer: B. Produce oxygen

20. Microorganisms are useful in:

A. Medicine and food production
B. Only causing diseases
C. Only pollution
D. Only soil damage

Answer: A. Medicine and food production

Assignment – The Invisible Living World: Beyond Our Naked Eye

1 Mark Questions

1. What are microorganisms?

Answer: Microorganisms are very small living organisms that cannot be seen with the naked eye.

2. Name one unicellular organism.

Answer: Amoeba.

3. Which instrument is used to see microorganisms?

Answer: Microscope.

4. Which microorganism is used in making curd?

Answer: Lactobacillus.

5. What is Spirulina?

Answer: Spirulina is a microalga rich in nutrients.

6. Which microorganism lacks a true nucleus?

Answer: Bacteria.

7. Name one microorganism used in baking.

Answer: Yeast.

8. Which group of microorganisms can make their own food?

Answer: Algae.

9. What is a nucleoid?

Answer: It is an irregular region in bacteria containing genetic material.

10. Which vitamin is present in Spirulina?

Answer: Vitamin B12.

2 Marks Questions

1. Differentiate between unicellular and multicellular organisms.

Answer: Unicellular organisms consist of a single cell (e.g., Amoeba), while multicellular organisms have many cells (e.g., fungi).

2. Why can fungi not prepare their own food?

Answer: Fungi lack chloroplasts, so they cannot perform photosynthesis.

3. What is the importance of microorganisms in decomposition?

Answer: Microorganisms break down dead organic matter into simpler substances, recycling nutrients in nature.

4. Write two uses of microorganisms.

Answer: They are used in making food (curd, bread) and medicines (antibiotics).

5. What are antibiotics?

Answer: Antibiotics are medicines produced by microorganisms that kill harmful bacteria.

3 Marks Questions

1. Describe the structure of bacteria.

Answer: Bacteria are unicellular organisms with a cell membrane and cell wall. They lack a true nucleus and instead have a nucleoid. They do not have membrane-bound organelles.

2. Explain the useful and harmful effects of microorganisms.

Answer: Microorganisms are useful in food production, medicine, and decomposition. However, some cause diseases in humans, animals, and plants.

3. Why is Spirulina considered a superfood?

Answer: Spirulina is rich in protein, vitamin B12, and nutrients, with low fat and sugar. It provides health benefits and is easy to cultivate.

4. Explain nitrogen fixation.

Answer: Nitrogen fixation is the process by which certain bacteria convert atmospheric nitrogen into usable forms for plants.

5. Describe the role of microorganisms in daily life.

Answer: Microorganisms help in making food like curd and bread, producing medicines, decomposing waste, and maintaining ecological balance.

Class 8, all subjects CBSE Notes in english medium, cbse class 8 Science Curiosity notes, class 8 Science Curiosity notes english medium, cbse 8 Science Curiosity cbse notes, class 8 Science Curiosity revision notes, cbse class 8 Science Curiosity study material, ncert class 8 science notes pdf, class 8 science exam preparation, cbse class 8 physics chemistry biology notes