Formation of the Earth's Atmosphere. The early Earth was very different from our Earth today. The early Earth experienced frequent impacts from asteroids and meteorites and had much more frequent volcanic eruptions. There was no life on Earth for the first billion years because the atmosphere was not suitable for life.
Phototropism as photo means light
eg: photosynthesis
The definition of calories is a measure of energy in food, specifically the measure of heat needed to raise a kilogram or a gram of water by one degree Celsius.
