AGAMOUS is a gene that has been implicated in the regulation of stamen formation in Arabidopsis flowers. If this is true, a mutant with a functional AP3 gene but a nonfunctional AGAMOUS gene would

Question

A.  produce petals but not stamens.
B.  produce stamens but not petals.
C.  produce petals and stamens.
D.  not produce stamens or petals.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?
 
Gather Content
· What do you already know about the evolution of flower development genes?
 
Consider Possibilities · Consider the different answer options. Which can you rule out?
 
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.  produce petals but not stamens.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses flowering gene evolution.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
· What key words does the question contain and what do they mean?
        o Stamens are the male portion of a flower. They carry pollen on the anthers on the ends of the filaments.
        o Arabidopsis is the best-studied genetic model plant. It is a eudicot.
        o The AP3 and AGAMOUS genes are MADS box genes involved in flower development.
 
Gather Content
· What do you already know about the evolution of flower development genes?
        o The flower development gene AP3 evolved its function by a series of two gene duplication and divergence events.
        o A gene duplication can facilitate evolution because it provides a backup gene that can mutate without being lethal to the organism.
        o In eudicots, AP3 retains its role in stamen development, and has a new role in petal formation as well. AP3 mutant plants do not produce either petals or stamens.
 
Consider Possibilities · Consider the different answer options. Which can you rule out?
        o Would an AGAMOUS-, AP3+ plant produce stamens but not petals? No. As the question says, AGAMOUS is required for stamens, but not petals.
        o Would an AGAMOUS-, AP3+ plant produce petals and stamens? No. AGAMOUS is required for stamens, so they cannot form without AGAMOUS.
        o Would an AGAMOUS-, AP3+ plant not produce stamens or petals? No. AGAMOUS is required for stamens, but not petals. Only stamens will fail to form.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would an AGAMOUS-, AP3+ plant produce petals but not stamens? Yes. As the question says, AGAMOUS is required for stamens, but not petals. Since AP3 is wild type, there is no reason petals will not form. However, if AGAMOUS and AP3 are both required for stamens, functional AP3 alone cannot do the job without AGAMOUS too.
        o Actually, an AGAMOUS mutant produces extra petals in the inner whorls!
 
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 what would happen if AGAMOUS was mutant but AP3 was functional.
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that when two genes both are required for the development of a feature, disruption of either gene alone will disrupt development?