Bell Work
HAVE SLATE, MARKER, AND ERASER ON DESK
1. Draw a food chain for your critter. Include at
least 5 organisms.
2. Label each organism with vocab from Thursday
(phototroph, herbivore, scavenger, etc.)
***If you finish early, describe how your critter gets
its food (does it hunt? Does it hide? Explain)
1
Instructions for notes/participation
When you see this pencil symbol next to
something, you must write it in your
notes
When you see the marker, answer the
question on your slate & wait for the
guest teacher to ask everyone to show
(No marker? Participate on scratch paper)
Behold!
I come to
speak to
you of…
Title for
today’s notes
(lined
paper)
Trophic Levels and
the Rule of Ten
What does the Praying Mantis gain
from eating the cricket?
But is some of the energy in the cricket destroyed,
when the mantis demolishes the cricket?
NO!
1st Law of Thermodynamics:
Energy cannot be created or destroyed; it is only transferred.
Ten days later…
According to the 1st Law of Thermodynamics no energy is
destroyed in this short food chain.
Discuss with your partner: does the lizard gain all of
the energy that was in the cricket? Why or why not?
Secondary
Consumer
The different levels we looked at
in food chains and food webs
are called
Trophic Levels
Primary
Consumer
Producer
These levels have different
names based on how far up they
are from the base.
Who is always going to be at the
base?
The producer is the producer. ( HAS TO BE AN AUTOTROPH)
The primary consumer is the first consumer. (HAS TO BE A HETEROTROPH)
The secondary consumer is the second consumer.
Energy is lost between trophic levels in a number of ways.
I used
energy
to move!
I used
energy in
cellular
respiration!
I lost energy in my
poo! (Did you cook with it?)
Trophic level = an organism’s level in a food web/chain
I lost
energy
as heat!
Yo tambien!
Me as well!
Where is all this heat
coming from?
Any biological process
that requires energy such
mating, hopping,
growing, changing colors,
growing hair, urinating,
swimming, smelling,
hunting, being
endothermic, biting,
digesting, eating, and
avoiding being eaten
releases heat.
Transfer of Energy
• When a zebra eats the grass, it does
not obtain all of the energy the grass in
the ecosystem. Some is not eaten,
some of what is eaten is not absorbed,
some energy is lost as heat during
digestion.
• Lions eat zebras, but they do not get
all of the energy from the zebra
population. (much of it is lost as heat,
bones, uncaught zebras)
Transfer of Energy
• The two (2) previous examples of
energy transfer show that no
organism EVER receives all of the
energy from the organism they just
ate
• Only 10% of the energy from one
trophic level is transferred to the
next
The Rule of Ten
1,000 cal
100 cal
10 cal
1 cal
Rule of Ten:
Only 10% of the energy gained by one trophic
level is available to the next level.
Rule of 10 Model
• Flip your notes over & draw a circle at the top center of
your page.
• This represents a red tail hawk, a top-level predator in
our local food web. Label your “hawk” a tertiary consumer.
• Are red-tail hawks
autotrophs or
heterotrophs?
Heterotrophs!
Rule of 10 Model
• Hawks eat pack rats. There must be at least 10
pack rats to support each red tail hawk.
• Display this by drawing 10
smaller circles in a pile or
row beneath the “hawk”.
• Pack rats are considered to be secondary
consumers. Label the “pack rats” as secondary
consumers.
Rule of 10 Model
• Pack rats in this area eat grasshoppers. Since
the model now has 10 pack rats, how many
TOTAL grasshoppers would you expect to find
in this area?
100!
• Grasshoppers are represented by smaller
circles of another color. Make 100 small dots
in a separate level under the
“pack rats”.
• “Grasshoppers are
primary consumers
___________
in this food web.”
Rule of 10 Model
• Grasshoppers in this area eat, well… grass.
• For the number of grasshoppers you modeled in this population
how many grass plants would you expect to find?
1000!
• You do NOT have to draw
the grass
plants on your model. Just
write the NUMBER of dots you would
have to draw & label it as “grass”
• As the only auto
_____trophs in this
food web, grass in classified as a
producer. (fill in the blank on slate)
12 word summary
• Underneath your Rule of 10 model write a
12 word summary about how the Rule of 10 is
related to population sizes of different species.
What Is Life? Quiz
• No one can sit right next to anyone else
– 1 person per lab table & in middle section
– 3 people @ counter
• If you finish early- turn into front basket &
quietly read/draw/listen to MP3 until
everyone is finished
If 10 mins+ extra time practice on next
two slides
• Take food web cards out to lab
• Use the trophic vocab cards to label each
organism (phototroph, chemotroph, etc.)