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The Moths and the Trees
The Forest Ecosystem diagram shows part of a forest ecosystem. Tussock moths are
native to the forest ecosystem. In the fall, tussock moths lay eggs on Douglas fir trees.
In the spring, tussock moth larvae eat the needles of the Douglas fir trees.
State of Washington
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The Moths and the Trees
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1. In the forest ecosystem, moths have predators such as birds. The organisms and the
environment represent an interacting system.
c) Nitrogen cycles through ecosystems. Both moths and trees have nitrogen-containing
molecules in their cells. Describe how nitrogen from the atmosphere can become part
of molecules in a tree.
State of Washington
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Task Title: The Moths and the Trees
Item number: 1
Performance Description
A 4-point response demonstrates the student understands:
Content Standard LS2A: Matter cycles and energy flows through living and nonliving components in
ecosystems. The transfer of matter and energy is important for maintaining the health and sustainability
of an ecosystem.
Item Specification 3: Describe the cycle of nitrogen through ecosystems.
AND
SYSB: Systems thinking can be especially useful in analyzing complex situations. To be useful, a
system needs to be specified as clearly as possible.
Item Specifications 4: Describe how a given system functions with respect to other systems.
Item and example response
Points
LS2A(3)/SYSB(4)
c) The response describes how nitrogen from the atmosphere can become part of
molecules in a tree
Examples:
 Nitrogen from air is changed by bacteria in soil to a form trees can absorb through
their roots.
 Nitrogen in air is changed by lightning and carried by rain to soil to be taken in by
trees.
 Nitrogen from air can be converted into fertilizer and spread on soil to get into the tree
through the roots.
State of Washington
10/21/2014
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Response A
1. First the nitrogen is in the atmosphere.
2. Bacteria in the soil change that N into a different substance.
3. Roots take in the new nitrogen substance.
Response B
N2 is in the air and goes into the soil. The Bacteria in the soil makes it (nitrogen)
so the N2 can go into the tree.
Response C
bacteria in the soil changes nitrogen into a different form
Response D
The nitrogen cycle is when N2 goes into the plants through the roots through
bacteria when animals die and decompose their (animals) body decomposes into
the soil, as well as the waste from animals that goes from ammonia to nitrogen.
Response E
The nitrogen is in the air and nitrogen is changed or fixed by lighting or bacteria
in soil and it (nitrogen) goes through the roots of the tree and that is how air is
changed into a form usable by the tree.
State of Washington
10/21/2014
The Moths and the Trees
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Response F
For the tree to have nitrogen, nitrogen gets fixated by a single celled organism
into the soil and the roots of the tree absorbs the nitrogen from the soil.
Response G
the nitrogen fixing bacteria in soil changes the N2 from the atmosphere it
(nitrogen) goes into the roots of the plant.
Response H
it (nitrogen) gets fixed by special bactieria when the plant or animal decays then
they (plant or animal) get broken down then become part of the ground later the
bactiria fix it (nitrogen) then the tree take it (nitrogen) in through their (tree)
roots.
State of Washington
10/21/2014
The Moths and the Trees
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