4.2 Energy Flow Flashcards
Essential Idea:
Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat
Explain how chemical energy is formed, and explain Biomass
Producers capture the sun’s light energy and convert it to chemical energy in the process of photosynthesis
CO2 + H2O + light → C6H12O6 + O2
Chemical energy is used to create BIOMASS
Biomass = the total dry mass of organisms within an area or volume
Chemical energy is used to create biomass
The stored energy in biomass is passed on when consumers feed
Organisms in most ecosystems get their energy from the sun, though consumers get it indirectly by feeding
what is a food chain
A food chain shows a linear sequence of organisms, starting with a producer and ending with a predator, that feed on each other
There are between 2-5 organisms in a food chain, but not more
Arrows show the flow of energy between organisms
cell respiration
Cell respiration is the conversion of chemical energy into a form that cells can use
C6H12O6 + O2 → CO2 + H2O + ATP
Cell respiration releases heat when organic compounds are converted to ATP
Organisms can convert many types of energy:
Light energy to chemical energy in photosynthesis
Chemical energy to kinetic energy in muscle contraction
Chemical energy to electric energy in neurons
Chemical energy to heat energy in heat generating adipose tissue (for homeostasis)
But once the energy becomes heat, organisms cannot convert it to any other form of energy
4.2 U6 Heat is lost from ecosystems
The heat generated by cell respiration is useful to organisms
It makes ectothermic (cold-blooded) animals warmer, which allows them to be more active
It is used by endothermic (warm-blooded) animals to maintain a constant body temperature in homeostasis
Heat moves from warmer areas to colder areas, so the heat is lost to the environment
The heat in the ecosystem is eventually lost into space
4.2 U7 Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels
Trophic level: the position of the organism in a food chain
Producers are on the first trophic level, primary consumers on the second, secondary consumers on the third, tertiary consumers on the fourth
When biomass is consumed, energy is transferred
Energy transfers between trophic levels is inefficient
Only about 10% of the energy available at one trophic level is passed on to the next
Energy is lost:
As heat from respiration
Not consumed (bones, fur, etc.)
As feces
Why are food chains and biomass limited by
energy loss between trophic levels?
A: Because there is not much energy available at
higher trophic levels- just 0.1% or less
That’s why you see fewer tigers (apex predators) than trees (producers)!
Pyramids of energy
show the flow of energy between trophic levels (kJm^-2y^-1)
