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Item CA026004: Many of the same genes code for homologous traits (forelimbs) across different species.

Assume that some type of forelimbs were present in the common ancestor of birds, crocodiles, whales, pigs, and humans, and that those ancient forelimbs evolved into the arms, wings, and fins of animals that exist today. What would be true about the genes that code for forelimbs in these different animals that evolved from the forelimbs of the common ancestor?

  1. Many of the same genes would code for forelimbs in all of these animals.
  2. Completely different sets of genes would code for forelimbs in each of these animals.
  3. Information about the body structures of common ancestors of different species provides no information about similarities and differences in the genes of those species.
  4. Many of the same genes would code for arms in crocodiles and pigs, but these genes would be completely different from the genes that code for wings in birds or fins in whales.

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. Many of the same genes would code for forelimbs in all of these animals. 40% 30% 40% 41% 38% 39% 46%
B. Completely different sets of genes would code for forelimbs in each of these animals. 16% 26% 16% 15% 17% 16% 15%
C. Information about the body structures of common ancestors of different species provides no information about similarities and differences in the genes of those species. 14% 22% 14% 14% 14% 14% 15%
D. Many of the same genes would code for arms in crocodiles and pigs, but these genes would be completely different from the genes that code for wings in birds or fins in whales. 30% 22% 30% 29% 31% 30% 23%

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. Many of the same genes would code for forelimbs in all of these animals. 53% 50% 56% 58% 55% 56% 44%
B. Completely different sets of genes would code for forelimbs in each of these animals. 8% 17% 7% 11% 4% 7% 11%
C. Information about the body structures of common ancestors of different species provides no information about similarities and differences in the genes of those species. 15% 17% 11% 13% 12% 12% 11%
D. Many of the same genes would code for arms in crocodiles and pigs, but these genes would be completely different from the genes that code for wings in birds or fins in whales. 25% 17% 26% 18% 29% 25% 33%

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. Many of the same genes would code for forelimbs in all of these animals. 54% 67% 53% 51% 56% 53% 50%
B. Completely different sets of genes would code for forelimbs in each of these animals. 12% 0% 12% 13% 11% 13% 0%
C. Information about the body structures of common ancestors of different species provides no information about similarities and differences in the genes of those species. 8% 0% 8% 11% 5% 8% 0%
D. Many of the same genes would code for arms in crocodiles and pigs, but these genes would be completely different from the genes that code for wings in birds or fins in whales. 26% 33% 27% 25% 27% 26% 50%