Lecture 23 Flashcards
BLahhh
THIS IS A GOOD LECTURE TO GO BACK OVER
Trophic Levels
Division of species in an ecosystem on the basis of their main nutritional source
Primary Consumers
Herbivores
-Eat producers
Secondary Consumers
Carnivores
-Eat herbivores
Third and higher level consumers
Feed on other carnivores
Decomposers
Secrete enzymes that digest dead organisms into simpler compounds
Detritovores
Ingest dead organisms, digestive wastes
Primary Producers
- Support all other trophic levels
- Autotrophs
- Make their own food from compounds and energy obtained from environment
Photosynthesis
The use of solar energy to produce food (sugar) from CO2 and water
CO2 + Water + Light Energy —> Sugar + O2
Cellular Respiration
The breakdown of food for energy using oxygen
Sugar + O2 —> ATP + CO2
Gross Primary Productivity (GPP)
Amount of energy captured by producers in a given unit of area in a given time period
Energy pathways in ecosystem
- Most primary producers use light energy from the sun and convert this light energy to chemical energy
- Only a tiny fraction of light energy is captured by producers by way of photosynthesis
Net Primary Productivity (NPP)
Amount of energy available to consumers (herbivores, decomposers, detritivores)
NPP=GPP-Energy lost to respiration
What do plants do with energy?
1) Used for cellular respiration (maintenance)
2) Stored as plant biomass (growth and reproduction)
Secondary Production
Production of new tissue by primary consumers
Endotherms
Trap heat from metabolism and maintain a body temperature different than of surroundings.
-They have less energy to channel into new biomass
Ectotherms
Body temperature is close to surrounding temperature
-More energy can be channeled into new biomass
Ecological (trophic) Efficiency
Ratio of net productivity at one trophic level to net productivity at the trophic level below it
-Varies from 5%-20% in nature with ~10% being common
Pyramids of Production
The amount of energy passing through each trophic level decreases as it moves up the food web
-10% average trophic efficiency necessitates short food webs
Pyramids of Biomass
Progressive loss of energy along a food chain limits the overall biomass of top-level carnivores that an ecosystem can support
Biological Magnification
Some toxins become more concentrated in successive trophic levels of a food web
-The biomass of any given level is produced from a much larger biomass ingested from the level below
