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Massachusetts Comprehensive Assessment System

2015, High School Biology

  Question 45: Open-Response  
Marine iguanas, Amblyrhynchus cristatus, live on the Galápagos Islands. Scientists think these marine iguanas evolved from iguanas that dispersed to the islands from the South American mainland, about 900 km away.
  1. Explain why geographic isolation on the Galápagos Islands favored the evolution of a new iguana species.
Marine iguanas are herbivores. They dive into the cold ocean to find algae to eat. When the iguanas are not feeding, they rest on the lava rocks near the island shores to warm their bodies. Compared to land iguanas, marine iguanas have darker body coloring, flatter tails, shorter snouts, and longer, curved claws.
  1. Choose one of the adaptive body features of marine iguanas listed above and describe how this feature is beneficial to marine iguanas in their environment.
  1. According to natural selection, describe how marine iguanas would have evolved the feature you identified in part (b).

Scoring Guide and Sample Student Work
Select a score point in the table below to view the sample student response.

ScoreDescription
4 The response demonstrates a thorough understanding of evolution through natural selection. The response clearly explains why geographic isolation on the Galápagos Islands favored the evolution of a new iguana species, provides a valid description of how a chosen adaptive feature benefits marine iguanas, and clearly describes how marine iguanas would have evolved the feature.
4
3 The response demonstrates a general understanding of evolution through natural selection.
2 The response demonstrates a limited understanding of evolution through natural selection.
1 The response demonstrates a minimal understanding of evolution through natural selection.
0 The response is incorrect or contains some correct work that is irrelevant to the skill or concept being measured.

Note: There are 2 sample student responses for Score Point 4.

High School Biology

Question 12: Ecology
Question 23: Biochemistry and Cell Biology
Question 32: Anatomy and Physiology
Question 44: Genetics
Question 45: Evolution and Biodiversity

Return to the MCAS 2015 Student Work Directory



Last Updated: September 23, 2014
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