STUDENT INSTRUCTION AND ANSWER SHEET

Activity 3: Extreme Life Styles - What Are the Limits?

Read the following on-line written materials about life in extreme environments.

Be sure to examine the link labeled Punishing Environments at the beginning of the article and the link labeled Images of Extremophiles at the end of the article.

"Chapter #17: Microbial Diversity in Archaea" from Brock -Biology of Microorganisms by Madigan, Martiko and Parker:
http://cw.prenhall.com/bookbind/pubbooks/brock/chapter17/deluxe.html
This excerpt provides a brief synopsis of Chapter #17 on the ways different archaea exist in extreme environments.

"Inroduction to the Archaea" from UC Berkeley's Museum of Paleontology:
http://www.ucmp.berkeley.edu/archaea/archaea.html

Answer the following questions based on your readings from these sources.

A. What are the three primary branches of the tree of life?

B. In which branch(es) of the tree of life do we find plants and animals?

C. In which branch(es) do we find single celled organisms that lack a nucleus?

D. At how high of a temperature does life become too extreme for eukarya?

E. What is the name of the organism thought to live at the greatest temperature? At what temperature does it live? Where does it live?

F. What is thought to happen at temperatures above 150^oC that prevents all life forms from existing above this temperature?

G. List the different species that scientists have found living in the extremely cold Antarctic sea-ice.

H. How do organisms live without freezing in extremely cold environments?

I. At what temperature do Polaromonas vaculota grow best? At what temperature does life begin to become too warm for Polaromonas vaculota?

J. How do halophiles adjust their structure to cope with life in extremely salty conditions?

K. What range of values in pH does an acidophile prefer? What about an alkaliphile?

L. Do acidophiles have high acidity in their cells? Explain why or why not.

M. Create a list of the most extreme conditions that life has been found to exist in here on Earth. Include information about extreme temperatures, pH, elevation limits, light levels, radiation exposure, size, and oxygen availability. If possible try to list an example organism that lives at each extreme.

N. What is unique about the cell walls of archaea?

O. What would a halophile do to adapt to a change in the salinity of the solution in which it was living?

P. Which extremophiles use inorganic carbon in anaerobic respiration to produce organic carbon and the by product CH4?

Q. What is the electron acceptor utilized by all hyperthermophiles in metabolism?

R. Is the electron acceptor from question Q an energy source or a carbon source? Is it oxidized or reduced?