Write true or false for the following statements :

Oxygen is necessary to life for most of the organisms in the process of respiration but some forms of life, especially bacteria, are poisoned by elemental oxygen.

Write true or false for the following statements :

Oxygen is returned to the atmosphere in only one major process, that is, respiration.

Write true or false for the following statements :

The process of nitrogen-fixing is done by bacteria in the presence of oxygen.

Write true or false for the following statements :

Carbon dioxide is one of the greenhouse gases.

Write true or false for the following statements :

Another process that adds to the CO₂ in the atmosphere is the process of photosynthesis where fuels are burnt to provide energy for various needs.