Energy and Matter

Principles Module 2


  • define matter and energy and explain how these two interact in biological systems
  • describe the flow of energy in the biosphere
  • list some of the key elements involved in the cycling of energy and matter through the biosphere

Key points

  • matter cycles, energy does not
  • all energy comes from our star and enters the biosphere via photosynthesis
  • the unity of life means all organisms use similar molecules to store and transport energy
  • big picture connections between photosynthesis and respiration
  • the unit of metabolism is the cell
  • water, carbon, P, N, S form the key molecules of life

In-class activities

All living things are constantly taking in energy in some form and converting it to matter. In the case of heterotrophs, energy enters the system in the form of high-energy bonds in foods, whereas autotrophs absorb energy directly and store it by creating high-energy bonds. Your job today is to unravel the food chain that gave you the energy and matter to get here today. Be as specific as possible about where energy entered the food chain, how it was stored and transferred to you, and how you are using it as you sit in class and think.