A high concentration of chlorophyll imbedded in the plasma membrane fold of a newly discovered species of bacteria suggests a:

Question

A.  Chemolithoautotrophic metabolism
B.  Chemoheterotrophic metabolism
C.  Photoautotrophic metabolism
D.  Photoheterotrophic metabolism

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
 
Gather Content
· What do you already know about bacterial metabolism? How does it relate to the question?
· What other information is related to the question? Which information is most useful?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
 

Answer 1

C.  Photoautotrophic metabolism

Clarify Question
· What is the key concept addressed by the question?
        o You have discovered a new bacterium in a lake. Looking at it under the microscope, you notice a lot of green chlorophyll molecules embedded in folds in its plasma membrane. How does this bacterium get energy?
· What type of thinking is required?
        o This question is an “apply” question. You need to apply your knowledge of bacterial metabolism to a new situation.
 
Gather Content
· What do you already know about bacterial metabolism? How does it relate to the question?
        o In general, bacteria can either produce their own energy or get energy by consuming other organisms. Autotrophic organisms produce their own energy (auto = self). Heterotrophic organisms get energy by consuming others (hetero = other).
        o Bacteria such as cyanobacteria get energy from sunlight by doing photosynthesis. Are these bacteria autotrophs or heterotrophs?
        o Bacteria such as rhizobia, which live in legume roots, get energy by oxidizing nitrogen. These bacteria are categorized as chemolithotrophs. There are a variety of chemolithotrophs, and they can oxidize nitrogen, sulfur, or hydrogen. Some live at the bottom of the ocean next to volcanic vents. Are these bacteria autotrophs or heterotrophs?
· What other information is related to the question? Which information is most useful?
        o Chlorophyll is a green pigment found in a variety of organisms, including many green plants. What is it used for?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o This question can actually be broken into two parts. First, determine whether the organisms is a chemolithotroph or a phototroph. Then determine whether the organisms is an autotroph or a heterotroph. Use this information to pick between the four options.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to determine the type of metabolism used by a bacterium that has a lot of chlorophyll in its membrane.
        o If you got the correct answer, great job!
        o If you got an incorrect answer, where did you get stuck?
            · Did you figure out that chlorophyll is used for photosynthesis? Green plants have it in their chloroplasts and cyanobacteria have it embedded in their plasma membranes. Your new bacterium probably does photosynthesis to get energy. A few bacteria, such as purple sulfur bacteria, are photoheterotrophs, but the presence of a lot of chlorophyll makes it more likely that your bacterium is a photoautotroph.