Nitrogen Fixation

Question 1 Name the micro-organism which can fix atmospheric nitrogen in the soil?

Question 2 What type of plants can fix nitrogen gas of the air into compounds of nitrogen?

Question 3 Name the micro-organism present in the soil and in the root nodules of leguminous plants?

Question 4 Where do Rhizobium live?

Question 5 What is the function of Rhizobium bacteria?

Question 6 What is meant by nitrogen-fixation?

Question 7 State the ways in which nitrogen gas of the atmosphere can be fixed in nature  to get nitrogen compounds in the soil?

• NCERT Solutions Class 8 Science

Nitrogen fixation

Our atmosphere has 78% nitrogen gas. The atmospheric nitrogen gas cannot be utilised directly by the plants or animals.

The process of converting nitrogen gas of the atmosphere or air into compounds of nitrogen(which can be used by the plants)is called nitrogen fixation.

The nitrogen gas is the free nitrogen whereas nitrogen compounds are said to be fixed(converted into nitrogen compounds).

The nitrogen gas of atmosphere can be fixed

1)By certain nitrogen-fixing bacteria present in the soil

2)By Rhizobium bacteria present in the root nodules of leguminous plants

3)By blue green algae

4)By lightning

The nitrogen fixing Rhizobium bacteria lives in the root nodules of leguminous plants.

Some nitrogen-fixing bacteria live freely in the soil whereas other nitrogen-fixing bacteria live in the root nodules of leguminous plants.

Nitrogen gas of atmosphere also gets fixed through the action of lightning in the sky. When lightning takes place in the sky during thunderstorm, a high temperature is produced in the atmosphere. At this high temperature, nitrogen gas of air combines with oxygen gas of air to form nitrogen compounds. These nitrogen compounds dissolve in rain water, fall to earth with rain water and go into the soil.

Other Notes from Chapter 2 Micro Organisms Friend and Foe

• Micro-Organisms
• Groups of Micro Organism
• Where do Micro Organism Live
• Useful Micro organism
• Making of Curd and Bread
• Commercial Use of Micro organism
• Medicinal Use of Micro oragnaism
• Increasing Soil Fertility
• Cleaning the Environment
• Harmful Micro Organism
• Carriers of Disease causing micro organism
• Disease Causing Micro organisms in Animals
• Disease Causing Micro-Organism in Plants
• Food poisoning
• Preservation of Food
• Preservation by sun-drying, Heating, Cooling
• Preservation by Deep Freezing,Common Salt, Sugar
• Preservation of food by mustard oil and Vinegar, Chemicals, Pasteurisation, Air-tight Packets
• Nitrogen Cycle