Let's analyze each statement one by one based on the given data for Paramecium contractile vacuole contractions at different salt concentrations.
The data is as follows:
- Very high: 2 contractions per minute
- High: 8 contractions per minute
- Medium: 15 contractions per minute
- Low: 22 contractions per minute
- Very low: 30 contractions per minute
Now, let's consider each statement:
1. The graph has five bars of equal height.
- This statement is incorrect because the number of contractions per minute differs significantly based on the concentration of salt. The heights of the bars are not equal.
2. The bars range from tallest for very high concentration to shortest for very low concentration.
- This statement is incorrect. In the given data, the highest number of contractions per minute (30) is associated with the very low salt concentration and the lowest number of contractions per minute (2) is associated with the very high salt concentration. The bars would range from the shortest for very high concentration to the tallest for very low concentration.
3. The bar for very low concentration is twice the height of the bar for medium concentration.
- To check this, we can compare the number of contractions:
[tex]\[
\text{Ratio} = \frac{\text{Contractions at very low concentration}}{\text{Contractions at medium concentration}} = \frac{30}{15} = 2
\][/tex]
This statement is correctly describing the data.
4. The bar for very high concentration is five times the height of the bar for very low concentration.
- To verify this, we again compare the number of contractions:
[tex]\[
\text{Ratio} = \frac{\text{Contractions at very high concentration}}{\text{Contractions at very low concentration}} = \frac{2}{30} \approx 0.0667
\][/tex]
This statement is incorrect as the contractions for very high concentration are much smaller in comparison to very low concentration; it is actually around 0.067 times the height of the very low concentration bar.
Thus, the statement that correctly describes the bars on a bar graph representing the data is:
The bar for very low concentration is twice the height of the bar for medium concentration.
