Item EM054006: Spur length varies within a population of columbine flowers. (Recognize a statement that describes the variability shown in a bar graph.)
The columbine is a flowering plant with long projections called "spurs" that contain nectar. Nectar is a sweet tasting liquid that attracts insects and animals. The organisms that feed on the nectar are called pollinators, because they move pollen from male to female flowers during this feeding process. The graph below shows spur length in a sample from a columbine population.
Left: Diagram of a columbine flower and a pollinator feeding on nectar in a spur. Right: Graph of spur length in a sample from a columbine population.
Which of the following claims about spur length does this graph support?
- Spur length is changing over time.
- Spur length varies among individuals in the population.
- Spur length is undergoing natural selection in the population.
- Spur length is the same throughout the population
Pre-Test
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. | Spur length is changing over time. | 15% | 20% | 15% | 15% | 16% | 16% | 16% |
| B. | Spur length varies among individuals in the population. | 63% | 52% | 63% | 64% | 61% | 63% | 63% |
| C. | Spur length is undergoing natural selection in the population. | 20% | 24% | 19% | 18% | 22% | 20% | 16% |
| D. | Spur length is the same throughout the population | 2% | 4% | 2% | 3% | 1% | 2% | 5% |
Post-Test (Control)
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. | Spur length is changing over time. | 16% | 30% | 16% | 13% | 19% | 16% | 33% |
| B. | Spur length varies among individuals in the population. | 64% | 61% | 65% | 65% | 63% | 64% | 44% |
| C. | Spur length is undergoing natural selection in the population. | 16% | 9% | 16% | 17% | 16% | 16% | 22% |
| D. | Spur length is the same throughout the population | 3% | 0% | 3% | 6% | 2% | 3% | 0% |
Post-Test (Treatment)
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. | Spur length is changing over time. | 7% | 0% | 7% | 8% | 6% | 7% | 0% |
| B. | Spur length varies among individuals in the population. | 73% | 100% | 72% | 73% | 71% | 74% | 55% |
| C. | Spur length is undergoing natural selection in the population. | 19% | 0% | 19% | 18% | 20% | 18% | 45% |
| D. | Spur length is the same throughout the population | 1% | 0% | 1% | 0% | 2% | 1% | 0% |