Transcript Chapter 3.1 - Liberty Union High School District

Chapter 3
The law of conservation of energy states that energy
may neither be created nor destroyed. Therefore the
sum of all the energies in the system is a constant.
Page 60
Photosynthesis
Another example off the “interweb”… what do you see that’s different from the last slide?
Page 60
Gross and net primary productivity
The amount of energy available in an ecosystem determines how much life the ecosystem can support.
Producers typically capture only
about 1 percent of available solar
energy via photosynthesis. The
energy they capture (gross
primary productivity, or GPP) can
be divided into energy used for
the producers’ respiration and
energy available for the
producers’ growth and
reproduction (net primary
productivity, or NPP).
(Friedland page 63)
1st Law of Thermodynamics: Just as matter can
neither be created nor destroyed, energy is
neither created nor destroyed.
– You can’t get something from nothing. When an organism needs biologically usable
energy, it must convert it from an energy source such as the Sun or food.
2nd Law of Thermodynamics: when energy is
transformed, the quantity of energy remains the
same, but its ability to do work diminishes.
Energy efficiency is the ratio of the amount of work that is done to the total
amount of energy that is introduced into the system in the first place.
Energy (Trophic) Pyramid
Trophic pyramid
Figure 3.9
Trophic pyramid for the
Serengeti ecosystem.
This trophic pyramid
represents the amount
of energy that is present
at each trophic level,
measured in joules (J).
While this pyramid assumes 10 percent ecological efficiency,
actual ecological efficiencies range from 5 to 20 percent across
different ecosystems. For most ecosystems, graphing the
numbers of individuals or biomass within each trophic level
would produce a similar pyramid.
(page 39)
Recycling Organisms
In the end, each trophic level eventually produces dead individuals and
waste products that feed other organisms
• Scavengers are carnivores, such as vultures, that consume dead
animals.
• Detritivores are organisms, such as dung beetles, that specialize in
breaking down dead tissues and waste products (referred to
as detritus) into smaller particles.
• These particles can then be further processed by decomposers: the
fungi and bacteria that complete the breakdown process by recycling
the nutrients from dead tissues and wastes back into the ecosystem.
Without scavengers, detritivores, and decomposers, there would be no
way of recycling organic matter and energy, and the world would rapidly
fill up with dead plants and animals.
Calories
The energy needed to raise the temperature of 1 gram of water through 1 °C
Food Chain / Web