Your friend examines an ivy vine growing on the side of a campus building and says, “Look – some of the branches on this plant have a different morphology. The leaf shapes and patterning are different, and there are flowers on some branches but not others. There must have been a mutation!” You respond,

Question

A.  “I think you’re right. Maybe there was a mutation in the LEAFY (LFY) gene, and the loss of LFY has promoted flowering and had pleiotropic effects on leaf morphology.”
B.  “No, those branches have just undergone phase change. Now they’re in the adult form, and have become competent to respond to flowering signals.”
C.  “I think you’re right. Maybe the embryonic flower (emf) gene is being overexpressed, and that’s causing flowers to form.”
D.  “No, those morphological changes are just evidence that this plant’s environment has changed during its lifetime.”

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 flowers? What other information is related to the question?

Choose Answer
Given what you now know, what information 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

B.  “No, those branches have just undergone phase change. Now they’re in the adult form, and have become competent to respond to flowering signals.”

Clarify Question
What is the key concept addressed by the question?
        · This question is asking you to explain why one plant can have different morphologies and flowering patterns in different regions.
What type of thinking is required?
        · Evaluate level:
            o This question is asking you to evaluate the reason that a single plant can exhibit different morphologies simultaneously.

Gather Content
What do you already know about flowers? What other information is related to the question?
        · Immature plants cannot produce flowers.
        · Phase change marks the time at which a plant has matured and can produce flowers.
        · Phase change may be obvious morphologically, but that is not always the case.
        · The LEAFY gene promotes flower formation.
        · The emf gene causes flowers to form abundantly.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · The presence of flowers on the plant indicates that the plant has gone through phase change and is not immature. Since flowers are present in some but not all parts of the vine, it is unlikely that the emf gene is being overexpressed.

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?
· Evaluate level:
        o Answering this question correctly depended on your ability to evaluate the reason that a plant can have different morphologies in different branches. If you got an incorrect answer, did you remember that morphology can differ as a result of phase change, or the criteria to compare different morphologies includes the concept of phase change? Did you have trouble weighing the merits of variable morphology to determine the correct answer?