Energy in an Ecosystem
Get out your HW and grab your
ecosystems…
Quiz: Get out a pencil and answer the question.
Make sure to put your name/date on the paper
given to you.

If you start with 1000kg of biomass of primary
producers, how much biomass would you have
of…
1.
2.
3.
4.
5.
Primary Consumers?
Secondary Consumers?
Tertiary Consumers
Why does a biomass diagram form a pyramid?
What is biomass?
Where does the Energy come from?


All the energy in an
ecosystem comes from the
sun.
1 - 2 % of the sun’s energy
that strikes the earth is
absorbed by plants


The rest is absorbed by abiotic
objects or deflected to space
Plants use that energy
through photosynthesis to
produce sugar (glucose)
which can then be converted
to the biomass of the plant.
Biomass


Biomass – This
is the mass of all
matter at any
level in a food
chain
The amount of
biomass in a
food chain
creates a
pyramid
(diagram).
Pyramid of Biomass


Approximately 10%
of biomass at one
level becomes
biomass at the next
level.
The other 90% is
uneaten, undigested
(this energy is
available to
decomposers) or
given off as heat
from the activities of
the organism.
Decrease in Biomass


Biomass decreases
with each additional
step upward in a food
chain.
Energy is lost as heat
(and cannot be
reused) in each step
of the food chain
(diagram on next
slide)
Pyramid of Numbers

This is a pyramid
showing that a
large number of
organisms (see
primary
productivity) is
required at the
base of the food
chain (there are
exceptions) to
support a small
number of
organisms at the
top.
Biomass Pyramid Video

http://www.youtube.com/watch?v=NJplkrliUEg
Answer these questions…

The number of organisms at the highest level
in a food chain is directly related to the
number of levels in the chain. How can more
organisms be supported in an ecosystem?

What is the difference between a pyramid of
biomass and a pyramid of numbers?