In ecosystems, energy is transmitted as light, chemical, and heat
Light energy is converted to chemical bond energy
molecules of carbohydrates, proteins, nucleotides, lipids all have higher energy than CO2 and water
food - is both energy content and material (C, N, P and other elements)
- for example:
- we eat sugar --> C go to biochemicals, energy goes to what's stored and what's lost
- i.e. following carbon in sugar molecules is the same as following the energy
- but - carbon content IS NOT the same as energy content (it's a proxy)
- carbohydrates have about 4 kcal/g (glucose has 696 kcal per mole)
- fats have about 9 kcal/g (much more energy efficient per weight)
follow energy and C in an organism
carbohydrates --> stored as organic carbon and CO2
energy in carbohydrates --> stored in biochemicals and lost as heat
two very closely related models
but follow energy and P or N (such as in algae or plant growth)
separate, almost independent flows
