Item CA018003: Cats and dogs became two different species when two groups in the ancestral species population became separated and could no longer breed with each other. Over time, the descendants of one group became cats and descendants of the other group became dogs.
Cats and dogs are descended from the same ancestor species. Which scenario best describes how this happened?
- One group of individuals in the ancestral species population bred with a different, more cat-like species, while another group bred with a different, more dog-like species.
- Two groups in the ancestral species population became separated from each other and could no longer breed with each other. Over many generations, the descendants of one group became cats and descendants of the other group became dogs.
- There were two different groups in the ancestral species population that could interbreed with each other. Over many generations, one group changed into cats and the other group changed into dogs.
- There were two groups in the ancestral species population that interbred with each other. Then they stopped breeding with each other, they became two different species, cats and dogs.
Pre-Test
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 572 |
6–8 n = 18 |
9–12 n = 502 |
Male n = 245 |
Female n = 283 |
English n = 511 |
Other n = 18 |
||
| A. | One group of individuals in the ancestral species population bred with a different, more cat-like species, while another group bred with a different, more dog-like species. | 33% | 22% | 33% | 30% | 35% | 33% | 33% |
| B. | Two groups in the ancestral species population became separated from each other and could no longer breed with each other. Over many generations, the descendants of one group became cats and descendants of the other group became dogs. | 39% | 39% | 39% | 43% | 35% | 39% | 39% |
| C. | There were two different groups in the ancestral species population that could interbreed with each other. Over many generations, one group changed into cats and the other group changed into dogs. | 18% | 33% | 17% | 18% | 18% | 18% | 17% |
| D. | There were two groups in the ancestral species population that interbred with each other. Then they stopped breeding with each other, they became two different species, cats and dogs. | 11% | 6% | 11% | 9% | 12% | 11% | 11% |
Post-Test (Control)
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 274 |
6–8 n = 14 |
9–12 n = 230 |
Male n = 119 |
Female n = 130 |
English n = 237 |
Other n = 9 |
||
| A. | One group of individuals in the ancestral species population bred with a different, more cat-like species, while another group bred with a different, more dog-like species. | 16% | 21% | 17% | 17% | 17% | 18% | 0% |
| B. | Two groups in the ancestral species population became separated from each other and could no longer breed with each other. Over many generations, the descendants of one group became cats and descendants of the other group became dogs. | 62% | 57% | 62% | 60% | 62% | 60% | 78% |
| C. | There were two different groups in the ancestral species population that could interbreed with each other. Over many generations, one group changed into cats and the other group changed into dogs. | 15% | 0% | 15% | 18% | 12% | 15% | 11% |
| D. | There were two groups in the ancestral species population that interbred with each other. Then they stopped breeding with each other, they became two different species, cats and dogs. | 7% | 21% | 6% | 5% | 9% | 7% | 11% |
Post-Test (Treatment)
Answer Choice |
Overall |
Grades |
Gender |
Primary Language |
||||
|---|---|---|---|---|---|---|---|---|
| n = 278 |
6–8 n = 4 |
9–12 n = 248 |
Male n = 130 |
Female n = 131 |
English n = 251 |
Other n = 5 |
||
| A. | One group of individuals in the ancestral species population bred with a different, more cat-like species, while another group bred with a different, more dog-like species. | 15% | 25% | 15% | 15% | 15% | 15% | 20% |
| B. | Two groups in the ancestral species population became separated from each other and could no longer breed with each other. Over many generations, the descendants of one group became cats and descendants of the other group became dogs. | 67% | 75% | 65% | 64% | 69% | 67% | 40% |
| C. | There were two different groups in the ancestral species population that could interbreed with each other. Over many generations, one group changed into cats and the other group changed into dogs. | 10% | 0% | 11% | 12% | 8% | 10% | 20% |
| D. | There were two groups in the ancestral species population that interbred with each other. Then they stopped breeding with each other, they became two different species, cats and dogs. | 8% | 0% | 8% | 10% | 8% | 8% | 20% |