Exercises: Analyzing and Graphing Data

Which SI unit would a scientist use to measure each of the following: (a) the mass of a seed, (b) the length of a leaf, (c) the volume of a liquid in a graduated cylinder, (d) the temperature of a water bath?

A student measures the height of a bean plant every 2 days. State which type of graph (bar graph or line graph) is best for showing how the height changes over time, and explain why. Then say which variable goes on the x-axis and which on the y-axis.

Emma recorded the mass of five seeds in grams: 0.42, 0.45, 0.40, 0.47, 0.41. Calculate the mean (average) mass of the seeds. Write your answer with the correct unit.

The table shows the number of bubbles of oxygen produced per minute by an aquatic plant at different distances from a lamp.

1. a) Describe the pattern in the data.
2. b) Identify the independent and dependent variables.
3. c) Calculate how much the bubble rate decreased from 10 cm to 40 cm, as a percent of the rate at 10 cm. Round to the nearest whole percent.

Jayden measures the time for a tablet to dissolve in water at different temperatures. He runs each temperature three times.

1. a) Calculate the mean dissolving time at each temperature.
2. b) Describe the relationship between temperature and dissolving time.
3. c) Explain why running three trials is better than running one.

Olivia counts the number of yeast cells in a sample every hour. A line graph of her data shows that the number of cells stays about the same for the first 2 hours, then rises steeply from hour 2 to hour 6, and then levels off. Her lab partner points out that the hour 4 measurement was taken with a different microscope.

1. a) Suggest one reason the population might level off after hour 6.
2. b) Identify a possible source of error in her data and explain how it could affect the results.
3. c) Describe one way to reduce that error.

A class tests how the concentration of salt in water affects the percent of brine shrimp eggs that hatch. Each group used 100 eggs per container.

1. a) Describe the relationship between salt concentration and hatching, including the approximate concentration that appears best.
2. b) Calculate the rate of change in hatching (eggs per g/L) between 10 and 20 g/L and between 40 and 50 g/L.
3. c) Explain why a conclusion that "more salt always increases hatching" is not supported.
4. d) Identify two limitations of the data and propose one improvement.

Marcus compares two fertilizers. He measures plant height (cm) after 21 days in five plants for each group.

1. a) Calculate the mean height for each group and the range for each group.
2. b) Marcus says Fertilizer Y is just as good as Fertilizer X because the means are similar. Use the means and ranges to evaluate his claim.
3. c) Write a claim-evidence-reasoning (CER) statement about which treatment most reliably increased growth.