1. the mitochondria has been described as the engine of the cell. why is this a fitting nickname? how is this organelle involved in the process of cellular respiration? 2. explain how one of the processes discussed in this module (photosynthesis, cellular respiration or the carbon cycle) apply to both the law of conservation of matter and law of conservation of energy. 3. identify one source of carbon that can found in each of these four spheres: atmosphere (air), geosphere (land), biosphere (living organisms) and hydrosphere (water).