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Massachusetts Comprehensive Assessment System

2016, Grade 8 Science and Technology/Engineering

  Question 21: Open-Response  
In cats, a single gene codes for hair length. The form of the gene for short hair (H) is dominant to the form of the gene for long hair (h).
  1. Identify the structures where the gene for hair length is stored in the nucleus of a cell.
  2. What percentage of a mother cat’s genetic information is inherited by her offspring?
A cat that has long hair (hh) is crossed with a cat that has short hair (Hh). The Punnett square below represents this cross.
Diagram shows a Punnett square consisting of four cells. Above the top left cell is uppercase H. Above the top right cell is lowercase h. To the left of the top left cell is lowercase h. To the left of the bottom left cell is lowercase h. Top left cell has uppercase H lowercase h. Top right cell has lowercase h lowercase h. Bottom left cell has uppercase H lowercase h. Bottom right cell has lowercase h lowercase h.
  1. Use the Punnett square to determine the probability that an offspring of these two cats will have long hair.
  2. Explain how you determined your answer to part (c).

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 that organisms have genes or instructions that are stored in chromosomes, and that these instructions are inherited from one generation to another. The response correctly identifies the structure where the gene for hair length is stored in the nucleus and the percentage of the mother’s genetic information inherited by her offspring. The response also correctly determines and clearly explains the probability of the offspring of the two cats having long hair.
4
3 The response demonstrates a general understanding that organisms have genes or instructions that are stored in chromosomes, and that these instructions are inherited from one generation to another.
2 The response demonstrates a limited understanding that organisms have genes or instructions that are stored in chromosomes, and that these instructions are inherited from one generation to another.
1 The response demonstrates a minimal understanding that organisms have genes or instructions that are stored in chromosomes, and that these instructions are inherited from one generation to another.
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.

Grade 8 Science and Technology/Engineering

Question 11: Physical Sciences
Question 21: Life Science

Return to the MCAS 2016 Student Work Directory



Last Updated: August 14, 2017
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