Which of the following statements would not be consistent with the theory for the endosymbiotic origin of mitochondria and chloroplasts?

Question

A.  Mitochondria and chloroplasts have their own DNA enclosed within a nuclear envelope.
B.  The composition of the outer membrane of chloroplasts and mitochondria is similar to the plasma membrane of eukaryotic cells.
C.  The composition of the inner membrane of chloroplasts and mitochondria is similar to the plasma membrane of prokaryotic cells.
D.  Mitochondria and chloroplasts have some enzymes unique to them.
E.  Genes encoded within mitochondria and chloroplasts indicate a closer relationship to prokaryotes than do most nuclear genes.


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 the origin of mitochondria and chloroplasts? How does it relate to the question?
 
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

A.  Mitochondria and chloroplasts have their own DNA enclosed within a nuclear envelope.

Clarify Question
· What is the key concept addressed by the question?
            · Three of the options are evidence that mitochondria and chloroplasts became organelles through endosymbiosis. You need to find the option that does not provide evidence of endosymbiosis.
· What type of thinking is required?
        o This question is an “evaluate” question. You need to judge which of the options provides the poorest evidence.
 
Gather Content
· What do you already know about the origin of mitochondria and chloroplasts? How does it relate to the question?
        o Mitochondria and chloroplasts were once free-living bacteria. They were engulfed by a larger cell and became endosymbionts. Over a very long period of time, they lost the ability to be free-living and became organelles. What traits do mitochondria and chloroplasts share with bacteria?
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The endosymbiosis theory states that mitochondria and chloroplasts were once bacteria that were engulfed by a larger, eukaryotic cell. Which option is inconsistent with that theory? Which option does not suggest that mitochondria and chloroplasts were once free-living bacteria?
 
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 which statement would not be possible if mitochondria and chloroplasts evolved from endosymbiotic bacteria. Bacteria do not have nuclear envelopes (neither do mitochondria or chloroplasts).
        o If you got the correct answer, great job!
        o If you got an incorrect answer, where did you get stuck?
            · The options were very wordy. Did you have trouble comparing them? Try rewriting them or drawing pictures to help you quickly see what each option is saying. That will help you compare them.