Real-World Lab
GUIDED INQUIRY
Pre-Lab: The Effect of Fertilizer on Algae
Problem How do excess nutrients affect the growth of algae?
Materials test tubes, test-tube rack, glass-marking pencil, dropper pipettes, algae culture, 25-mL graduated cylinder, spring water, plant food, cotton balls, grow light
Lab Manual Chapter 3 Lab
Skills Predict, Compare and Contrast, Infer
Connect to the 
In a healthy ecosystem, nutrients cycle among primary producers, consumers, and decomposers. The growth of primary producers is limited by the availability of nutrients. Humans can intentionally increase the amount of nutrients in an ecosystem. For example, farmers may add fertilizer to the soil in which they grow crops. But the addition of nutrients to an ecosystem is not always planned. For example, runoff from soil that contains fertilizer may flow into coastal waters or freshwater ponds. In this lab, you will observe what happens when algae that live in those waters are provided with excess nutrients.
Review What is a limiting nutrient?
Explain Why do farmers use fertilizers?
Classify What role do algae play in freshwater ecosystems?
Background Questions
Preview the procedure in the lab manual.
Design an Experiment What is the independent variable in this experiment?
Predict After four days, how will you be able to tell which test tube has more algae?
Control Variables Why will you grow Chlorella in spring water instead of pond water?
Visit Chapter 3 online to test yourself on chapter content and to find activities to help you learn.
Untamed Science Video Help the Untamed Science crew explore food relationships as they turn the ecological pyramid upside down.
Art in Motion View a short animation showing the different levels of organization.
Art Review Review your understanding of which organisms are producers and which are consumers with this drag-and-drop activity.
InterActive Art Build your understanding of the water cycle with this animation.
Data Analysis Collect and analyze some data so you can see how the data is used to monitor a site.
Tutor Tube Get some clarification on producers and consumers and learn how the flow of matter and energy is not what you may think!
Visual Analogies Compare a recycling center to decomposers in this activity. Compare nutrient limitation to a series of cogs in this activity.
Table of Contents
- Formulas and Equations
- Applying Formulas and Equations
- Mean, Median, and Mode
- Estimation
- Using Measurements in Calculations
- Effects of Measurement Errors
- Accuracy
- Precision
- Comparing Accuracy and Precision
- Significant Figures
- Calculating With Significant Figures
- Scientific Notation
- Calculating With Scientific Notation
- Dimensional Analysis
- Applying Dimensional Analysis