Chhattisgarh Board Class 8 Science Chapter 8 Solution

Chhattisgarh Board Class 8 Science Chapter 8 Solution

 

CG Board Class 8 Micro Organisms –A Wonderful World

 

Choose the correct alternative:-

 

Thing which cannot be seen by naked eyes are of the size –

• Smaller than 1 micron
• Smaller than 10 micron
• Smaller than 100 micron
• Smaller than 1000 micron

 

The first person to see micro organisms by observing bacteria through the self made microscope was –

• Robert Hooke
• Antonia Leewan Hawk
• Edward Jenner
• Louis Pasteur.

 

The germs causing malaria is –

• Bacteria
• Virus
• Protozoa
• Fungi

 

The micro-organisms present in the roots of bengal gram is –

• Bacteria
• Virus
• Protozoa
• Fungi

 

Mushroom is a ………………..

• Protozoa
• Algae
• Flower
• Fungi

 

HIV/AIDS is caused due to –

• Bacteria
• Virus
• Protozoa
• Fungi

 

Answer the following question in short :-

 

(1)     How does boot polish protect leather shoes?

Boot polish protects leather shoes by forming a protective layer on the surface of the leather, which helps repel water, dust, and other things.

 

(2)     Why does curd sometimes turn bitter?

Curd sometimes turns bitter due to the overgrowth of certain bacteria strains, such as Lactobacillus lactis or Lactobacillus fermentum, which produce lactic acid and other compounds that contribute to the bitter taste.

 

(3)     Why must the milk be lukewarm when curd is to be made from it?

Milk must be lukewarm when making curd because it provides an optimal temperature range (around 40-45°C) for the growth and activity of the bacteria cultures present in the curd starter, allowing them to ferment the milk and convert it into curd

 

(4)     How does the leguminous plants increase the fertility of the soil?

Leguminous plants increase the fertility of the soil by hosting nitrogen-fixing bacteria, such as Rhizobium, in their root nodules. These bacteria convert atmospheric nitrogen into a form that can be utilized by plants, thereby enriching the soil with nitrogenous compounds essential for plant growth.

 

(5)     Why must we safe guard food items from micro organisms?

We must safeguard food items from microorganisms to prevent food spoilage, contamination, and the spread of foodborne illnesses caused by harmful bacteria, fungi, viruses, and other pathogens present in the environment.

 

(6)     What are the medium through which micro organisms enter our body?