Bacteria Quiz - CBSE Class 8 Science

Free practice quiz: Bacteria (CBSE Class 8 Science). 20 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

Sample questions

1. What shape do most bacteria have?

   1. Spherical
   2. Square
   3. Triangular
   4. Pentagonal
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   Answer: A. Spherical

   Most bacteria are spherical in shape, also known as cocci.

2. Which type of bacteria stain purple in the Gram stain procedure?

   1. Gram-positive
   2. Gram-negative
   3. Mycobacteria
   4. Spirilla
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   Answer: A. Gram-positive

   Gram-positive bacteria take up the crystal violet dye and appear purple when stained.

3. What characteristic distinguishes archaea from bacteria?

   1. Presence of a nucleus
   2. Different cell wall composition
   3. Isolation methods
   4. Reproduction rates
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   Answer: B. Different cell wall composition

   Archaea have distinct cell wall compositions made up of proteins and polysaccharides.

4. What type of bacteria are pathogens?

   1. Beneficial bacteria
   2. Harmful bacteria
   3. Neutral bacteria
   4. Saprophytic bacteria
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   Answer: B. Harmful bacteria

   Pathogens are harmful bacteria that can cause disease in hosts.

5. What are biofilms?

   1. Colonies of different bacterial species
   2. Negative bacteria
   3. Single-celled bacteria
   4. Viruses
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   Answer: A. Colonies of different bacterial species

   Biofilms are dense clusters of microbial cells that adhere to surfaces, often involving various species.

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