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Item CA023003: 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 pigs, crocodiles, whales, and birds, and that those ancient forelimbs evolved into the arms, fins, and wings 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. Exactly the same genes would code for forelimbs in all of these animals.
  2. Many of the same genes would code for forelimbs in all of these animals.
  3. Many of the same genes would code for arms in pigs and crocodiles, but these genes would be completely different from the genes that code for wings in birds or fins in whales.
  4. Completely different sets of genes would code for forelimbs in these different kinds of animals.

Pre-Test

Distribution of responses (prior to studying evolution in high school)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 580
6–8
n = 25
9–12
n = 514
Male
n = 254
Female
n = 286
English
n = 526
Other
n = 13
A. Exactly the same genes would code for forelimbs in all of these animals. 8% 8% 7% 10% 5% 7% 8%
B. Many of the same genes would code for forelimbs in all of these animals. 47% 48% 46% 46% 47% 46% 23%
C. Many of the same genes would code for arms in pigs and crocodiles, but these genes would be completely different from the genes that code for wings in birds or fins in whales. 33% 24% 34% 31% 36% 33% 54%
D. Completely different sets of genes would code for forelimbs in these different kinds of animals. 13% 20% 13% 13% 12% 13% 15%

Post-Test (Control)

Distribution of responses (following typical high school instruction on evolution)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 255
6–8
n = 15
9–12
n = 195
Male
n = 97
Female
n = 119
English
n = 205
Other
n = 6
A. Exactly the same genes would code for forelimbs in all of these animals. 7% 13% 7% 6% 8% 7% 17%
B. Many of the same genes would code for forelimbs in all of these animals. 60% 40% 59% 61% 56% 60% 17%
C. Many of the same genes would code for arms in pigs and crocodiles, but these genes would be completely different from the genes that code for wings in birds or fins in whales. 25% 33% 25% 26% 24% 24% 67%
D. Completely different sets of genes would code for forelimbs in these different kinds of animals. 8% 13% 9% 7% 11% 9% 0%

Post-Test (Treatment)

Distribution of responses (following completion of an evolution curriculum module)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 301
6–8
n = 8
9–12
n = 274
Male
n = 134
Female
n = 150
English
n = 274
Other
n = 9
A. Exactly the same genes would code for forelimbs in all of these animals. 5% 13% 5% 7% 5% 5% 11%
B. Many of the same genes would code for forelimbs in all of these animals. 53% 38% 52% 55% 52% 52% 56%
C. Many of the same genes would code for arms in pigs and crocodiles, but these genes would be completely different from the genes that code for wings in birds or fins in whales. 35% 38% 36% 31% 37% 36% 22%
D. Completely different sets of genes would code for forelimbs in these different kinds of animals. 6% 13% 7% 7% 6% 7% 11%