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Item CA040003: Scientists can use similarities in the embryos of two animal species to help determine how closely they are related.

Scientists use various methods to determine how closely two species are related. One method is to compare the physical features of the two species and another is to compare their DNA. Can scientists also use similarities in the embryos of two animal species to help determine how closely they are related?

  1. No, comparing embryos of organisms does not help in determining how closely two animal species are related. Scientists can obtain the same information by comparing features of the adult organisms.
  2. No, comparing embryos of organisms does not help in determining how closely two animal species are related. The embryos change too much as they grow into adult organisms.
  3. Yes, comparing embryos is a useful way of determining how closely two animal species are related. There may be important similarities in the features of the embryos, even when adults of the species look very different.
  4. Yes, it is sometimes useful to compare embryos, but only when the adult organisms are very similar.

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. No, comparing embryos of organisms does not help in determining how closely two animal species are related. Scientists can obtain the same information by comparing features of the adult organisms. 4% 4% 4% 4% 5% 4% 15%
B. No, comparing embryos of organisms does not help in determining how closely two animal species are related. The embryos change too much as they grow into adult organisms. 17% 22% 16% 17% 16% 17% 8%
C. Yes, comparing embryos is a useful way of determining how closely two animal species are related. There may be important similarities in the features of the embryos, even when adults of the species look very different. 67% 65% 67% 67% 67% 67% 62%
D. Yes, it is sometimes useful to compare embryos, but only when the adult organisms are very similar. 12% 9% 12% 13% 12% 12% 15%

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. No, comparing embryos of organisms does not help in determining how closely two animal species are related. Scientists can obtain the same information by comparing features of the adult organisms. 5% 6% 5% 6% 4% 5% 0%
B. No, comparing embryos of organisms does not help in determining how closely two animal species are related. The embryos change too much as they grow into adult organisms. 15% 17% 14% 16% 16% 14% 22%
C. Yes, comparing embryos is a useful way of determining how closely two animal species are related. There may be important similarities in the features of the embryos, even when adults of the species look very different. 74% 67% 74% 74% 72% 74% 67%
D. Yes, it is sometimes useful to compare embryos, but only when the adult organisms are very similar. 6% 11% 7% 5% 9% 7% 11%

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. No, comparing embryos of organisms does not help in determining how closely two animal species are related. Scientists can obtain the same information by comparing features of the adult organisms. 3% 0% 3% 2% 3% 2% 13%
B. No, comparing embryos of organisms does not help in determining how closely two animal species are related. The embryos change too much as they grow into adult organisms. 9% 0% 10% 7% 12% 9% 38%
C. Yes, comparing embryos is a useful way of determining how closely two animal species are related. There may be important similarities in the features of the embryos, even when adults of the species look very different. 83% 100% 83% 83% 83% 83% 50%
D. Yes, it is sometimes useful to compare embryos, but only when the adult organisms are very similar. 5% 0% 5% 7% 3% 5% 0%