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Item CA024003: Many of the same genes code for homologous traits (forelimbs) across different species.

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

  1. Completely different sets of genes would code for forelimbs in these different animals.
  2. Many of the same genes would code for arms in crocodiles and pigs but these genes would be completely different than the genes that code for wings in birds or fins in whales
  3. Many of the same genes would code for forelimbs in all of these animals.
  4. There is no relationship between the traits of organisms and which genes for forelimbs the organisms have.

Pre-Test

Distribution of responses (prior to studying evolution in high school)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 558
6–8
n = 25
9–12
n = 498
Male
n = 243
Female
n = 274
English
n = 502
Other
n = 19
A. Completely different sets of genes would code for forelimbs in these different animals. 12% 12% 12% 14% 11% 13% 11%
B. Many of the same genes would code for arms in crocodiles and pigs but these genes would be completely different than the genes that code for wings in birds or fins in whales 40% 40% 39% 35% 43% 39% 42%
C. Many of the same genes would code for forelimbs in all of these animals. 44% 48% 45% 47% 44% 45% 37%
D. There is no relationship between the traits of organisms and which genes for forelimbs the organisms have. 3% 0% 3% 4% 3% 3% 11%

Post-Test (Control)

Distribution of responses (following typical high school instruction on evolution)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 294
6–8
n = 23
9–12
n = 247
Male
n = 109
Female
n = 171
English
n = 264
Other
n = 9
A. Completely different sets of genes would code for forelimbs in these different animals. 9% 17% 9% 8% 10% 9% 0%
B. Many of the same genes would code for arms in crocodiles and pigs but these genes would be completely different than the genes that code for wings in birds or fins in whales 24% 22% 23% 28% 22% 23% 56%
C. Many of the same genes would code for forelimbs in all of these animals. 65% 57% 66% 61% 66% 65% 44%
D. There is no relationship between the traits of organisms and which genes for forelimbs the organisms have. 2% 4% 2% 4% 2% 2% 0%

Post-Test (Treatment)

Distribution of responses (following completion of an evolution curriculum module)
Answer Choice
Overall
Grades
Gender
Primary Language
 
n = 281
6–8
n = 3
9–12
n = 257
Male
n = 132
Female
n = 140
English
n = 254
Other
n = 11
A. Completely different sets of genes would code for forelimbs in these different animals. 5% 0% 4% 6% 2% 4% 0%
B. Many of the same genes would code for arms in crocodiles and pigs but these genes would be completely different than the genes that code for wings in birds or fins in whales 32% 33% 32% 34% 32% 32% 45%
C. Many of the same genes would code for forelimbs in all of these animals. 61% 67% 62% 59% 64% 62% 55%
D. There is no relationship between the traits of organisms and which genes for forelimbs the organisms have. 2% 0% 2% 1% 2% 2% 0%