• A. Biodiesel from Microalgae

• 1. Scientists have been exploring the use of protists to produce biodiesel.

• 2. Biodiesel is a(n) fuel made mostly from living organisms.

Biodiesel from Microalgae

• B. Designing a Controlled Experiment

• 1. A type of scientific investigation that tests how one variable affects another variable is called a(n) controlled experiment.

• 2. In a controlled experiment, the control group contains the same factors as the experimental group, but the independent variable does not change.

Designing a Controlled Experiment

Lesson 3-2

• The dependent variable is the factor measured or observed during an experiment.

• The independent variable is the factor that you want to test. It is changed by the investigator to observe how it affects a dependent variable.

Designing a Controlled Experiment (cont.)

• C. Biodiesel

• 1. Rudolph Diesel invented the diesel engine.

• 2. Replacing food crops with fuel crops is not a good solution because there is a shortage of food in many parts of the world.

(cont.)

Lesson 3-2Designing a Controlled Experiment (cont.)

How do independent and dependent variables differ?

Lesson 3-4

• D. Aquatic Species Program

• 1. The Aquatic Species Program (ASP) initially studied possible ways that microalgae could capture excess carbon dioxide in the air.

• 2. ASP project leaders noticed that some microalgae strains produced large amounts of oil.

Aquatic Species Program

Lesson 3-5

• E. Which Microalgae?

• 1. Microscopic organisms that live in marine or freshwater environmentsare called microalgae.

• 2. During photosynthesis, microalgae produce oils that can be converted into biodiesel.

Which Microalgae?

Lesson 3-6

• F. Oil Production in Microalgae

• 1. Starving microalgae of nutrients, such as nitrogen, increases the amount ofoil they produced.

• 2. Starving the microalgae also caused their size to decrease, resulting in no overall increase in oil production.

Oil Production in Microalgae

Lesson 3-6• G. Outdoor Testing v. Bioreactors

• 1. Growing microalgae in open ponds can be challenging but might be less expensive than other methods.

• 2. Some researchers are now growing algae under controlled conditions in closed glass containers called bioreactors.

Outdoor Testing v. Bioreactors

Lesson 3-6•H. Why So Many Hypotheses?

•1. Dr. Richard Sayre, a biofuel researcher, said that all the ASP research was based on forming hypothesis.

•2. According to Dr. Sayre, to get research support, a scientist has to develop a(n) question and propose some strategies.

Why So Many Hypotheses?

Lesson 3-6• Increasing Oil Yield

•1. Microalgae uselight energy, water, and carbon dioxide to make sugar.

•2. Scientists from a biofuel company wondered whether microalgae oil yields could be increased by distributing light to all microalgae.

Increasing Oil Yield

Lesson 3-6• J. Bringing Light to Microalgae

• 1. Researchers and engineers used light rods to feed artificial light tomicroalgae in a(n) bioreactor.

• 2. Paddlewheels continuously rotate microalgae to the surface so theorganisms are exposed to more light.

Bringing Light to Microalgae

Lesson 3-6Bringing Light to Microalgae (cont.)

K. Why Grow Microalgae?1. Power plants that burn fossil fuels release carbon dioxide into theatmosphere, which contributes to global warming.2. Microalgae use carbon dioxide during photosynthesis and producesugar, which can then be converted to oil.

Lesson 3-6

Lesson 3-6• L. Are microalgae the future?

• 1. The costs of growing microalgae are currently too high to competewith petroleum -based diesel.

• 2. Microalgae-based biodiesel might one day become an affordablereality in the United States.

Are microalgae the future?