Networks
1. What is a “network”? Be thorough in your explanation.
2. Explain how an ecosystem is a network.
 Use the network terms “nodes” and “edges” in your answer.
 Define what the different nodes are. Define what the different edges are.
3. Compare and contrast the cell phone network with an ecosystem network.
 For both networks, define what the nodes are and what the edges are.
 Use specific examples from each network to clarify your answer.
 For both networks, describe the effect that removing nodes or edges had
on the rest of the network.
4. Describe why scientists use computers to analyze networks. What do
computers allow us to do that cannot be done easily by hand? (address both
questions in your answer)
Halobacteria experiment
1. How does salinity affect the population growth of halobacteria?
 Support your answer using specific data from your experiment.
Overall Unit and Learner Analysis
Please take a moment to reflect on this unit.
a. Describe what you previously knew, before completing this unit, in
reference to the ecological, extremeophile, and network concepts.
b. Describe any misconceptions you may have had (i.e. you thought all
lakes had freshwater only). Try to offer possible reasons why you may
have previously thought this? (i.e. you have never seen a salt water
lake in person.)
c. Describe what you learned from this unit that has not already been
addressed in your answers above.
d. Please list any questions you have in reference to this unit that have
been left unanswered.
e. Describe what you think you could have done to make your learning
more complete?
Institute for Systems Biology & Bellevue School District
ANSWER KEY AND RUBRIC
Networks
What is a “network”? Be thorough in your explanation.
1pt = below standard, 2 pts = standard, 3 pts = exceeds standard
 collection or group of individual parts
 relationships between individual parts
 parts together form a system / act as a whole / have overall properties
different from the individual parts
Explain how an ecosystem is a network.
 Use the network terms “nodes” and “edges” in your answer.
 Define what the different nodes are. Define what the different edges are.
1-3pts = below standard, 4pts = standard, 5-6pts = exceeds standard
 nodes = populations or species
 edges = energy relationships


nodes = abiotic factors
edges = biotic-abiotic relationships


illustrates overall flow of energy and matter through ecosystem
changes in one part of system affect other parts of system / overall system
responds to change
Compare and contrast the cell phone network with an ecosystem network.
 For both networks, define what the nodes are and what the edges are.
 Use specific examples from each network to clarify your answer.
 For both networks, describe the effect that removing nodes or edges had
on the rest of the network.
1-5pts = below standard, 6pts = standard, 8pts = exceeds standard
Ecosystem:
 nodes = populations or species (or abiotic factors); edges = energy
relationships (or abiotic-biotic relationships)
 specific example of each
 removing node may prevent other organisms from getting energy
(only 1 point allowed from following 2)
o removing node may not prevent other organisms from getting energy,
depending upon number of connections with others / other pathways of
information flow
o removing node may increase competition for food because of fewer
possible energy pathways in ecosystem
Institute for Systems Biology & Bellevue School District
Cell phone:
 nodes = people / phones; edges = information / calling relationships
 specific example of each
 removing node or edge disrupts flow of information to others
 removing node or edge may not disrupt flow of information, depending upon
number of connections with others / other pathways of information flow
Describe why scientists use computers to analyze networks. What do computers
allow us to do that cannot be done easily by hand? (address both questions in
your answer)
1-2pts = below standard, 3pts = standard, 4-5pts = exceeds standard
 visualize all interactions
 trace connections
 remove nodes / edges
 activate nodes / edges
 analyze how changes in one part affect the other parts of the network
Halobacteria experiment
How does salinity affect the population growth of halobacteria?
 Support your answer using specific data from your experiment.
1pt = below standard, 2pts = standard, 3pts = exceeds standard
 increasing salinity increases the growth of halobacteria / higher salt
concentration causes more growth of halobacteria
 more growth at 3.8 and 4.3 molar salt solution than at 2.3, 2.8, 3.3 molar salt
solution
 optical density relates to population size of halobacteria / higher optical
density means more halobacteria
Overall Unit and Learner Analysis
This metacognitive exercise is meant to help develop the student’s critical
thinking skills. It is also meant to give the teacher insight into the way the student
thinks and to help evaluate the current and past directions of the curricular
materials. Accept thoughtful answers on a completion basis.
Institute for Systems Biology & Bellevue School District