Brief-Constructed Response
Energy in Ecosystems
Teacher Guide
Objectives assessed: The student will be able to:
• Describe predator/prey, parasite/host, and producer/consumer relationships as they occur in
food webs within marine ecosystems
• Describe producer/consumer relationships as they occur in food webs within freshwater
ecosystems
Students will need about 15–20 minutes to complete this brief constructed response.
1.
Organisms in the ocean interact with each other all the time. Describe an example of a
predator/prey, a parasite/host, and a producer/consumer relationship that happen in the
marine ecosystem.
Correct response(s):
Sample Correct Response: Part I Organisms are always interacting with each other. In the
marine ecosystem, there are many examples of these interactions. As an example of
producer/consumer relationships, diatoms are the major producer in the ocean. They make
oxygen for most of the planet. These algae are eaten by organisms as small as zooplankton
to those as large as the great whales. Marine producers are the bottom of the food chain. In
predator/prey relationships, predators are those that hunt other organisms, which are
considered their prey. The most feared predator in the ocean is the great white shark. It
feeds upon smaller fish, squid, seals, small whales, and basically whatever it can find. It is
an eating machine. Parasite/host relationships also exist in the oceans. Many fish can be
infected with tapeworms. The tapeworms enter the fish when their eggs are swallowed. The
tapeworms hatch after passing through the digestive system of the fish and landing in the
intestine. Here, the tapeworm will grow by absorbing the nutrients that the fish should be
getting. Ultimately, if the fish cannot get rid of the tapeworm, it will die.
Response scoring tool:
Content
Score
Response identifies; correct relationships of predator/prey, parasite/host,
3
and producer/consumer that exist in the oceans; examples of predator
prey include sharks/smaller fish; examples of parasite/host include
tapeworm/fish; examples of producer/consumer include
diatoms/zooplankton.
Response correctly identifies; two of three relationships (predator/prey,
2
parasite/host, producer/consumer) and provides examples for those.
Response correctly identifies; one of the three relationships.
1
No response, or response not appropriate to the question.
0
Brief-Constructed Response: Energy in Ecosystems
© 2010 Discovery Education
Page 1 of 2
Brief-Constructed Response
Energy in Ecosystems
Teacher Guide
2.
Freshwater organisms have many of the same relationships as those in the ocean. Describe
an example of a predator/prey, a parasite/host, and a producer/consumer relationship that happen
in a freshwater ecosystem.
Sample Correct Response: Part II Freshwater ecosystems have the same types of
relationships as those found in the oceans. The producer/consumer relationship is
exemplified by the mallard duck and the pondweed it eats. The pondweed is the producer,
making its energy from the Sun. The duck is the consumer, eating the producer. The
parasite/host relationship in the freshwater ecosystem can be the same as that of the
oceans, the tapeworm and fish. The tapeworm enters the fish and grows within the
intestines, absorbing the nutrients from the fish, ultimately killing it. The predator/prey
relationship is shown with the river otter and the freshwater mussels it eats. The otter is a
carnivore, and the mussels are filter-feeders.
Response scoring tool:
Content
Score
Response identifies; correct relationships of predator/prey, parasite/host,
3
and producer/consumer that exist in the oceans; examples of predator
prey include river otters/freshwater mussels; examples of parasite/host
include tapeworm/fish; examples of producer/consumer include
pondweed/ducks.
Response correctly identifies; two of three relationships (predator/prey,
2
parasite/host, producer/consumer) and provides examples for those.
Response correctly identifies; one of the three relationships.
1
No response, or response not appropriate to the question.
0
Teacher Notes:
Brief-Constructed Response: Energy in Ecosystems
© 2010 Discovery Education
Page 2 of 2