Lesson 1: Earth Systems and Interactions – We learned how Earth’s systems interact. Earth systems interact by exchanging matter and energy, which often change in form during the interactions. In the water cycle, water moves in the hydrosphere, changes to a gas and enters the atmosphere, and transfers thermal energy among all the systems. The rock cycle is a series of processes that take place deep within Earth as well as on the surface of the planet. The series of processes that continuously move carbon among Earth systems is called the carbon cycle. Some organisms take in CO2 through the process of photosynthesis and help cycle carbon through the biosphere. Through the process of cellular respiration, living organisms return CO2 to the atmosphere.