I did this experiment below with 6% molasses, 12%, and 25% molasses solution and I don't know If I should do a bar or line graph.
Yeast Populations
Student Materials
Yeast is a single-cell fungus that produces carbon dioxide as a byproduct of cellular respiration. The release of carbon dioxide causes bread dough to rise. Because the yeasts are small and reproduce rapidly, yeast organisms are useful for studying various factors such as food availability, temperature change and a shift in pH that may influence the rate at which a population grows. The optimum temperature for yeast metabolism and yeast reproduction is between 30 and 35 degrees Celsius depending on the species and providing there is an adequate food supply. These cells produce carbon dioxide gas as a waste product and the amount of carbon dioxide is an indication of yeast growth.
Your Task
You and your lab partner will grow yeast in a molasses solution (food for the yeast) and investigate how one factor influences the change in yeast growth as measured by the amount of carbon dioxide produced.
Suggested materials:
teacher prepared yeast suspension test tube rack
teacher prepared 25% molasses solution pH paper
several 1 ml graduated dropping pipettes clean test tubes (18 mm x 150 mm)
100 ml graduated cylinder clean test tubes (25 mm x 150 mm)
metric ruler safety goggles
weak acid/base (provided at teacher’s discretion) lab aprons
incubator electronic balance (optional)
Designing and Conducting Your Experiment
1. In your words, state the problem you are going to investigate. Write a hypothesis using an “If … then … because …” statement that describes what you expect to find and why. Include a clear identification of the independent and dependent variables that will be studied.
2. Design an experiment to solve the problem. Your experimental design should match the statement of the problem and should be clearly described so that someone else could easily replicate your experiment. Include a control if appropriate and state which variables need to be held constant.
General procedure for growing yeast populations:
1. Place 35 mL of 25% molasses solution into a small test tube.
2. Stir the yeast suspension and then place 1 mL of the yeast suspension into the same test tube.
3. Place the test tube in the rack.
4. Wash and rinse your hands. Place your palm over the end of the small test tube and invert it five times.
5. Carefully slide a larger tube down over the smaller tube. Quickly invert the tubes so the mouth of the large tube is up.
6. Using a metric ruler measure the height of the air bubble (mm or cm) in the smaller tube and record. Place in the test tube rack.
7. Incubate these samples for 24 hours at 30 degrees Celsius.
8. Measure the bubble and record the change in the size due to carbon dioxide gas production on your data table. (Subtract the initial gas bubble size from the total bubble size. After you measure the bubble you may carefully empty the gas from the small test tube and reset it. Remember you will need this data to calculate the total volume of carbon dioxide each day over five days.)
9. Repeat steps 6-8 for five days.
3. Review your design with your teacher before you begin your experiment.
4. Conduct your experiment. While conducting your experiment, take notes and organize your data into tables.
Safety note: Students must wear approved safety goggles and follow all safety instructions.
When you have finished, your teacher will give you instructions for cleanup procedures, including proper disposal of all materials.
Based on the information provided, you conducted an experiment to investigate how different concentrations of molasses solution affect yeast growth, as measured by the amount of carbon dioxide produced. Now, you are trying to decide whether to represent your data using a bar graph or a line graph.
To determine which type of graph is more appropriate, consider the nature of your data and the information you want to convey.
In this case, you are measuring the change in the size of the carbon dioxide bubble over time, specifically for five consecutive days. This data represents continuous and sequential measurements of one dependent variable (carbon dioxide production) over time.
When you have continuous data or want to show trends and patterns over time, a line graph is generally more suitable. Line graphs display quantitative data on both the x-axis (time in this case) and the y-axis (carbon dioxide production). The line connecting the data points indicates the changes and trends in the variable over time.
On the other hand, bar graphs are useful when you have non-continuous or discrete data. They display distinct categories or groups on the x-axis (such as different concentrations of molasses solution) and the corresponding values on the y-axis (carbon dioxide production). Bar graphs are effective for comparing and contrasting different groups or categories.
Based on the nature of your experiment and data, I recommend using a line graph to represent your results. This will clearly show the trends and change in carbon dioxide production over the five days for each concentration of molasses solution. Each concentration can be represented by a different line on the graph, allowing for easy comparison and analysis of the data.
Remember to label the x-axis as "Time (in days)" and the y-axis as "Carbon Dioxide Production (in mm or cm)". Additionally, include a title for the graph that reflects the purpose of the experiment and the variables being studied.
I hope this explanation helps you decide on the appropriate graph to represent your data. Good luck with your experiment!