Which two experiments best demonstrate that the gene AP3 is important for flower development? (Choose two)

Question

_____ When a wild type AP3 transgene is expressed in an AP3 mutant, the plant produces normal flowers.
_____ When AP3 is deleted, the plant produces deformed flowers.
_____  When the genes PI and AP3 are both deleted, the plant produces deformed flowers.
_____  When a wild type AP3 transgene is overexpressed, the plant produces normal flowers.
_____  When a wild type AP3 transgene is overexpressed, the plant produces deformed flowers.
_____  When AP3 is duplicated, the plant produces deformed flowers.

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 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

__X__  When a wild type AP3 transgene is expressed in an AP3 mutant, the plant produces normal flowers.
__X__  When AP3 is deleted, the plant produces deformed flowers.
_____  When the genes PI and AP3 are both deleted, the plant produces deformed flowers.
_____  When a wild type AP3 transgene is overexpressed, the plant produces normal flowers.
_____  When a wild type AP3 transgene is overexpressed, the plant produces deformed flowers.
_____  When AP3 is duplicated, the plant produces deformed flowers.


Clarify Question
· What is the key concept addressed by the question?
        o This question addresses flower development genes.
· What type of thinking is required?
        o This question is asking you to weigh and judge, or evaluate, evidence to choose the best of the possible answers.
· What key words does the question contain and what do they mean?
        o The gene AP3 is one of the plant MADS-box genes that is important in flower development.
 
Gather Content
· What do you already know about the flower development genes?
        o The flower development gene AP3 evolved its function by a series of two gene duplication and divergence events.
        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.
        o In the text, we saw how gene replacement experiments were used to determine that changes in the C-terminus of the protein are responsible for AP3’s new role in petal formation. The PI C-terminus could partially support stamen development, but not petal development.
 
Consider Possibilities
· Consider the different answer options. Which can you rule out?
        o Would a good experiment be that when the genes PI and AP3 are both deleted, the plant produces deformed flowers? No, because we don’t know which gene was responsible for the phenotype.
        o Would a good experiment be that when a wild type AP3 transgene is overexpressed, the plant produces normal flowers? No, because this would be the expected result (in a wild type plant).
        o Would a good experiment be that when a wild type AP3 transgene is overexpressed, the plant produces deformed flowers? This is not the best experiment, because even a gene unrelated to flower development could mess things up when overexpressed (in abnormally high levels, or wrong place, or both).
        o Would a good experiment be that when AP3 is duplicated, the plant produces deformed flowers? No. Again, this is not the best experiment because overexpression phenotypes may not always reflect the normal function of the gene.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Would a good experiment be that when AP3 is deleted, the plant produces deformed flowers? Yes, this tells us that AP3 is necessary for normal flower development.
        o Would a good experiment be that when a wild type AP3 transgene is expressed in an AP3 mutant, the plant produces normal flowers? Yes, this tells us that replacing just wild type AP3 is sufficient to restore the development of flowers.
        o These two experiments together tell us that AP3 is both necessary and sufficient for normal flower development (in the context of an otherwise normal genome).
 
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 which two experiments are best to demonstrate that the AP3 gene is necessary for flower development.
        o The question required you to weigh and judge, or evaluate, evidence to choose the best of the possible answers.
        o Did you recognize that the key experiments are to take AP3 away, and then to put it back?