Investigate Methanogens

August 27, 2002

Web posted at: 4:17 PM EDT (2017 GMT)

Overview: Using conditions similar to those that would appear on Mars, scientists have been able to grow microorganisms known as methanogens. The experiment confirms the belief among some that life could thrive on Mars. Have your students investigate methanogens and other archaebacteria and compare their characteristics to those of eubacteria. Ask students to speculate as to why scientists believe archaebacteria are typical life-forms on other planets.

Have students read the story "Air test suggests possible life on Mars," and answer the following questions:

1. Who is Tim Kral? What are methanogens? Describe the conditions under which Kral and his colleagues recently grew methanogens. What conditions were the researchers trying to simulate? What have scientists learned from recent successful missions to Mars? Besides water, what else would be necessary for life to exist on Mars?

2. How did Kral and his colleagues document the growth of the microorganisms in their experiment? How do methanogens get their energy? How does the experiment conducted by Kral and his team support the belief that life could exist on Mars?

3. In the story, we learn that, "Even if Mars does not have life, Kral speculates that methanogens brought along by colonizers could take root." If humans were to colonize Mars, how might the importation of methanogens benefit them? What do you think is meant by the term "terraforming"? Tim Kral cites "potential ethical and environmental problems" with terraforming. What do you think some of those ethical and environmental problems might be? How might human intervention in a planet's ecosystem be beneficial? How might such intervention be harmful? Should humans "terraform" other planets? Discuss.

4. Inform students that, according to Holt, Rinehart and Winston's Modern Biology, methanogens are archaebacteria, along with extreme halophiles and thermoacidophiles. Direct students to their texts and other resources to research the characteristics of these archaebacteria, including the way they harvest energy, and the environments in which they naturally thrive. Share students' findings and compare this information to what students know about eubacteria (the more common bacteria with which students are probably more familiar). Remind students that methanogens and other archaebacteria are anaerobic. Why is this a significant fact to scientists who are studying the possibility of life on other planets? Why do students think that scientists consider archaebacteria to be a good model of life-forms that may exist on other planets? Discuss.