Energy in ecosystems Photosynthesis – the processof combining carbon dioxide and water using sunlight energy to produce sugar (glucose). CO 2 + H 2 O —> O 2 + C 6 H 12 O 6 INPUTS Sunlight energy, carbon dioxide, water PROCESS Chlorophyll traps sunlight; the energy is used to split water molecules; hydrogen from water is combined with carbon dioxide to produce glucose. OUTPUTS Glucose used as an energy source and building blocks for other molecules and oxygen is released. TRANSFORMATIONS Light energy to stored chemical energy.

Energy in ecosystems Respiration – releases energy from glucose and other organic molecules inside all living cells. It begins as an anaerobic process in the cytoplasm of cells, and is completed inside mitochondria with aerobic chemical reactions. The process is controlled by enzymes. The energy released is in a form useable by living organisms but is ultimately lost as heat. O 2 + C 6 H 12 O 6 —> CO 2 + H 2 O INPUTS Glucose and oxygen PROCESS Oxidation reactions inside cells OUTPUTS Release of energy for work and release of heat. TRANSFORMATIONS Stored chemical energy to kinetic energy and heat

DEFINITIONS Measures of ENERGY into ecosystems  Gross productivity (GP) -the total gain in biomass or energy per unit area per unit time. UNIT (kj m -2 yr -1 )  Gross primary productivity (GPP) is gained through photosynthesis  Gross secondary productivity (GSP) is gained through absorption in consumers

DEFINITIONS Measures of ENERGY out of ecosystems  Net productivity (NP) - the total gain in biomass or energy per unit area per unit time remaining after respiratory losses (R).  Net primary productivity (NPP) - the gain by producers in biomass or energy per unit area per unit time remaining after respiratory loss (R).  Net secondary productivity (NSP) - the gain by consumers in biomass or energy per unit area per unit time remaining after respiratory loss (R).