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Goal 3 Concepts Of Biology

Expectation 3.4 The student will explain the mechanism of evolutionary change.

Indicator 3.4.2 The student will estimate degrees of relatedness among organisms or species.

Assessment Limits:

  • classification (recognize relationships among organisms; distinguish between prokaryotes and eukaryotes)
  • anatomical similarities (evolutionary relationships; homologous structures)
  • similarities of DNA base and/or amino acid sequence (including results from gel electrophoresis)

Brief Constructed Response (BCR) Item - Released in 2005

Scientists are studying how four species of deer are related. The scientists believe that Species 1 is the common ancestor. The four species have some traits in common. They also have traits that are unique to their species.

Scientists used the process of gel electrophoresis to study the relatedness of the four deer species. The results of their gel electrophoresis study are shown below.

Describe how three species of deer evolved from the common ancestor. In your response, be sure to

  • identify which species is most closely related to the common ancestor; explain your answer using the results of their gel electrophoresis
     
  • identify and describe the process that leads to the development of different species
     
  • explain what factors affect this process in the deer species
     
Type your answer in the answer box below.

The following 4 Sample Student Responses represent a range of score points.

Sample Student Response #1

image of student response

Score for Sample Student Response #1: Rubric Score 1

Annotation: This response shows some understanding of the question. The student correctly identifies the deer species most closely related to the common ancestor (species number 3) and provides a minimal description of how the gel was used to determine species relatedness (2 + 4 are so differents from common ancestor). While the brief description of how the gel electrophoresis process works supports the first part of the question, neither the process nor the factors affecting this process are addressed.


Sample Student Response #2

image of student response

Score for Sample Student Response #2: Rubric Score 3

Annotation: This response demonstrates a good understanding of the question. The student provides generally complete details, particularly about the natural selection process. The discussion of the only identified factor, geographic isolation, is somewhat weak, and the description of gel evidence is general (has the closest gel electrophoresis pattern). However, the student does show synthesis in connecting beneficial traits (that allow one to survive in a certain enviroment) with reproduction (after generations of passing on and improving upon the traits). The accurate use of scientific terminology (natural selection; traits) strengthens the response.


Sample Student Response #3

image of student response

Score for Sample Student Response #3: Rubric Score 2

Annotation: This response shows a basic understanding of the question. The student identifies the most closely related species (species 3) and provides a brief explanation of the gel evidence (gel elecrophor data shows the most similarities). Natural selection is identified as the process and described, beginning with genetic mutations and including survival and reproduction of the most-fit individuals (who can adapt to their environments). A factor that affects this process is identified (predation) and appropriately incorporated into the discussion. The supporting details are adequate.


Sample Student Response #4

image of student response

Score for Sample Student Response #4: Rubric Score 4

Annotation: This response shows a full and complete understanding of the question. The supporting details throughout this response are pertinent and complete, and the discussion of the gel evidence is thorough (the common ancestor and species 3 match up on more traits than any of the other species. While species 2 has two traits in common and species 4 has three traits in common, species 3 has five). The response completely describes natural selection. (Individuals with these necessary traits mate and produce offspring that also have those traits and can, therefore, survive. As time goes on, groups of one species in different environments develop the traits necessary to survive in their habitat by natural selection and are different from the species from which they originated.) Several factors that affect this process are identified and briefly explained. (As different groups of one species move to a new habitat, new adaptations and traits are required to survive there; habitat and environment affect the traits that are kept or die off by natural selection, removing them from the common ancestor.)


Additional Resources

Anchor Papers used in scoring

Brief Constructed Response (BCR) Rubric
Print: Scoring Rubric (pdf)
Score 4

There is evidence in this response that the student has a full and complete understanding of the question or problem.

  • Pertinent and complete supporting details demonstrate an integration of ideas.
  • The use of accurate scientific terminology enhances the response.
  • An effective application of the concept to a practical problem or real-world situation reveals an insight into scientific principles.*
  • The response reflects a complete synthesis of information.
Score 3

There is evidence in this response that the student has a good understanding of the question or problem.

  • The supporting details are generally complete.
  • The use of accurate scientific terminology strengthens the response.
  • The concept has been applied to a practical problem or real-world situation.*
  • The response reflects some synthesis of information.
Score 2

There is evidence in this response that the student has a basic understanding of the question or problem.

  • The supporting details are adequate.
  • The use of accurate scientific terminology may be present in the response.
  • The application of the concept to a practical problem or real-world situation is inadequate.*
  • The response provides little or no synthesis of information.
Score 1

There is evidence in this response that the student has some understanding of the question or problem.

  • The supporting details are only minimally effective.
  • The use of accurate scientific terminology is not present in the response.
  • The application, if attempted, is irrelevant.*
  • The response addresses the question.
Score 0

There is evidence that the student has no understanding of the question or problem.

  • The response is completely incorrect or irrelevant or there is no response.

* On the High School Assessment, the application of a concept to a practical problem or real-world situation will be scored when it is required in the response and requested in the item stem.

Updated 2002
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