What are two ways plants can be conserved, why are energy-saving stoves useful, what is biogas, what organisms help ferment organic matter, what materials can make biogas, and what are two advantages

Here are the answers to your questions:

1. Two ways plants can be conserved are:

   • Afforestation (planting more trees).
   • Protecting existing forests and preventing deforestation.

2. The use of energy-saving stoves is useful to the environment because it reduces the amount of wood fuel needed, thereby decreasing deforestation and lowering greenhouse gas emissions.

3. The gas fuel obtained by fermenting organic matter in an airtight container is called biogas.

4. The organisms that help in the fermentation of organic matter in a biogas digester are anaerobic bacteria (or methanogens).

5. Three materials that can be used to make biogas are:

   • Animal manure (e.g., cow dung)
   • Crop residues (e.g., straw, leaves)
   • Food waste

6. Two advantages of using biogas over conventional fuels are:

   • It is a renewable energy source.
   • It helps in waste management by converting organic waste into useful products.