Effect of fertilizer on bacteria (N8) - McREL

The picture below shows a pond ecosystem. Use this picture and what you know about the things in it to
answer the questions in this section.
1. What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
NAEP released item, grade 8

Question 1
Scoring Guide
Score & Description
Complete
Student response demonstrates an understanding <strong>of</strong> indirect effects in a system by correctly
predicting an increase in bacteria, and explaining that since there will be more algae, there will be
more bacteria decomposing the algae when the algae die and sink to the bottom <strong>of</strong> the pond.
Partial
Student response correctly predicts an increase in the number <strong>of</strong> bacteria, but fails to explain why,
or provides an incorrect explanation.
Unsatisfactory/Incorrect
Student response predicts an incorrect effect, and provides no reasonable explanation <strong>of</strong> the
processes at the bottom <strong>of</strong> the pond.
Complete - Student Response
1 What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
Scorer Comments:
Student response correctly predicts an increase in bacteria, and provides a clear explanation.
1 What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
Scorer Comments:
Student response correctly predicts an increase in bacteria, and explains that the increase in algae
NAEP released item, grade 8

would result in more dead organisms for the bacteria to eat.
Partial - Student Response
1 What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
Scorer Comments:
Student response correctly predicts an increase in bacteria, but provides an incorrect explanation
implying that the bacteria feed <strong>of</strong>f the <strong>fertilizer</strong>.
1 What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
Scorer Comments:
Student response correctly predicts an increase in bacteria, but provides an incorrect explanation
stating that bacteria is a plant and is thus fertilized.
Unsatisfactory/Incorrect - Student Response
1 What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
Scorer Comments:
Student response makes an incorrect prediction.
NAEP released item, grade 8

1 What effect would the <strong>fertilizer</strong> have on the bacteria in the mud at the bottom <strong>of</strong> the pond after one
month Why do you think the <strong>fertilizer</strong> would affect the bacteria this way
Scorer Comments:
Student response makes an incorrect prediction.
NAEP released item, grade 8

Score
2000 National Performance Results
Unsatisfactory/incorrect 69%
Partial 21%
Complete 0%
Omitted 8%
Off task 2%
Percentage <strong>of</strong> Students
Note:
• These results are for public and nonpublic school students.
• Percentages may not add to 100 due to rounding.
The Fields <strong>of</strong> Science: Life Sciences (Sub content classification: Ecology)
Knowing and Doing Science : Conceptual Understanding
The Fields <strong>of</strong> Science
Life Sciences
This question measures basic knowledge and understanding <strong>of</strong> the following:
Knowing and Doing Science
Conceptual Understanding
Conceptual understanding includes the body <strong>of</strong> scientific knowledge that students draw upon when
conducting a scientific investigation or engaging in practical reasoning. Essential scientific concepts
involve a variety <strong>of</strong> information, including facts and events the student learns from both science
instruction and experiences with natural environment; and scientific concepts, principles, laws, and
theories that scientists use to explain and predict observations <strong>of</strong> the natural world.
NAEP released item, grade 8