Answer: temperature, gravity, atmosphere, and water
The environment of the earth favours the sustainance of life on earth. The temperature of the Earth is influenced by the composition of the atmosphere, which consists of heat-trapping gases and chemicals produce due to volcanic eruption and human activities. Temperature varies according to the seasonal variations, global warming and other variables. Temperature provides a base for the existence of life on Earth. Gravity is a force that is exerted by the Earth, it attracts objects or organisms towards itself. It facilitates a substrate to the living organism. Atmosphere is a mixture of gases, some of these gases like carbon dioxide, oxygen and nitrogen supports life in a biosphere. These gases are necessary for photosynthesis, respiration and nitrogen fixation in living organisms. Water is a colorless, shapeless substance, which acts as a solvent. It is a chief component present in all organisms living on earth. Water is required for various processes like photosynthesis, respiration, and digestion.
