Transferring Euglena into a dark environment results in the loss of photosynthetic pigment. What conclusion does this support?

Question

A.  Euglenoids are obligate photoautotrophs.
B.  Light triggers heterotrophy.
C.  Euglenoids are closely related to plants.
D.  Euglenoids are neither plant-like or animal-like protists.

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 Euglena? 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

D.  Euglenoids are neither plant-like or animal-like protists.

Clarify Question
· What is the key concept addressed by the question?
        o This question is asking you to determine which statement is supported by the results of an experiment where Euglena was moved from light to dark.
· What type of thinking is required?
        o This is an “evaluate” question, so you need to look at each option and evaluate whether the results of your experiment support your conclusion. Remember, you moved Euglena from the light into the dark and saw the photosynthetic pigment disappear.
 
Gather Content
· What do you already know about Euglena? How does it relate to the question?
        o What sort of photosynthetic pigments have you learned about? One is chlorophyll, which is essential for photosynthesis. The very first step of photosynthesis involves chlorophyll absorbing energy from sunlight, so it is a very useful pigment. On the other hand, maintaining chlorophyll uses up energy. If a plant does photosynthesis intermittently, during non-photosynthetic periods it has to use up valuable sugars maintaining its chlorophyll.
· What other information is related to the question? Which information is most useful?
        o What are photoautotrophs? How are they different from heterotrophs?
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o You can go about answering this question in a couple ways:
            · You have four hypotheses. What experiment would you conduct to test each one? How well does the experiment described in the question’s stem match those methods?
            · You have observed that Euglena has photosynthetic pigment when growing in the light, but digests this pigment when growing in the dark. Which conclusion best explains what is going on?
        o Be careful when evaluating each option. Some of the statements themselves can be correct without being the correct answer. The correct answer is supported by the results of your experiment.
 
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 evaluate which statement was supported by the results discussed in the stem of the question. Answering the question depended on your ability to evaluate each of the statements.
        o If you got the correct answer, well done!
        o If you got an incorrect answer, where did the process break down? Did you pick “Light triggers heterotrophy”? Remember, you moved Euglena to the dark, triggering heterotrophy. This statement would be correct if you said “Dark triggers heterotrophy.”