Log In | Register

Item CA011002: If the DNA of Species X and Species Y is more similar than the DNA of Species X and Species Z, then Species X and Species Y have a more recent common ancestor than Species X and Species Z.

If the DNA of Species X and Species Y is more similar than the DNA of Species X and Species Z, what is a reasonable conclusion about the common ancestors of these three groups?

  1. Species X and Species Y have a common ancestor, but Species X and Species Z do not.
  2. Species X and Species Z have a more recent common ancestor than Species X and Species Y.
  3. Species X and Species Y have a more recent common ancestor than Species X and Species Z.
  4. Similarities in DNA do not provide information about whether two groups share a common ancestor.

Pre-Test

Distribution of responses (prior to studying evolution in high school)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 559
6–8
n = 23
9–12
n = 499
Male
n = 221
Female
n = 300
English
n = 516
Other
n = 13
A. Species X and Species Y have a common ancestor, but Species X and Species Z do not. 23% 22% 24% 26% 21% 24% 23%
B. Species X and Species Z have a more recent common ancestor than Species X and Species Y. 8% 4% 8% 7% 8% 9% 0%
C. Species X and Species Y have a more recent common ancestor than Species X and Species Z. 63% 65% 62% 60% 65% 62% 77%
D. Similarities in DNA do not provide information about whether two groups share a common ancestor. 5% 9% 6% 7% 5% 6% 0%

Post-Test (Control)

Distribution of responses (following typical high school instruction on evolution)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 281
6–8
n = 18
9–12
n = 229
Male
n = 109
Female
n = 135
English
n = 243
Other
n = 9
A. Species X and Species Y have a common ancestor, but Species X and Species Z do not. 17% 22% 16% 15% 19% 16% 22%
B. Species X and Species Z have a more recent common ancestor than Species X and Species Y. 8% 11% 7% 11% 4% 7% 0%
C. Species X and Species Y have a more recent common ancestor than Species X and Species Z. 72% 67% 74% 74% 73% 73% 78%
D. Similarities in DNA do not provide information about whether two groups share a common ancestor. 4% 0% 3% 0% 4% 3% 0%

Post-Test (Treatment)

Distribution of responses (following completion of an evolution curriculum module)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 305
6–8
n = 3
9–12
n = 280
Male
n = 139
Female
n = 150
English
n = 276
Other
n = 8
A. Species X and Species Y have a common ancestor, but Species X and Species Z do not. 8% 0% 9% 11% 6% 8% 25%
B. Species X and Species Z have a more recent common ancestor than Species X and Species Y. 8% 0% 9% 8% 9% 8% 13%
C. Species X and Species Y have a more recent common ancestor than Species X and Species Z. 81% 100% 79% 81% 80% 80% 50%
D. Similarities in DNA do not provide information about whether two groups share a common ancestor. 3% 0% 3% 1% 5% 3% 13%