Analyze data
A drug that stops cells in mitosis
- Unit 4
- 4 points
- About 10 minutes
You can use a calculator on this question, just like on exam day.
A short question with data in a table or graph. You describe what the data show, use the data to judge a hypothesis, and explain how the results connect to biology you know. On the exam: Question 6 of 6 in Section II; about 10 minutes suggested.
The question and its sources
Researchers studied a drug that prevents spindle microtubules from forming. They treated onion root tips with the drug for 6 hours and left other root tips untreated. They then counted the cells in each stage of the cell cycle in six root tips per treatment. Cells with condensed chromosomes that had not separated were counted as metaphase.
Table 1. Percent of root tip cells in each stage, mean ± 2SE
| Stage | Untreated | Drug-treated |
|---|---|---|
| Interphase | 86.0 ± 2.0 | 70.2 ± 2.4 |
| Prophase | 6.4 ± 1.0 | 7.0 ± 1.1 |
| Metaphase | 3.0 ± 0.8 | 22.4 ± 2.2 |
| Anaphase | 2.4 ± 0.6 | 0.2 ± 0.2 |
| Telophase | 2.2 ± 0.6 | 0.2 ± 0.2 |
Source: Hypothetical data
Suggested time: 10 minutes
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Part (a)
1 pointBased on Table 1, describe the effect of the drug on the percent of cells in anaphase.
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Part (b)
1 pointUsing Table 1, calculate the percent of drug-treated cells that are in any stage of mitosis.
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Part (c)
1 pointA student claims that the drug prevents cells from entering mitosis. Use the data to evaluate the student's claim.
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Part (d)
1 pointExplain why the drug causes cells to build up in metaphase.
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