(Note the phylogeny is drawn with diagonal branches rather than the rectangular branches seen in the text.) If the stop codon in the Brassica plant CAL gene appeared in the cauliflower lineage after broccoli and cauliflower had diverged from each other, it would be expected that

Question

A.  both broccoli and cauliflower flowers would be arrested as buds.

B.  both broccoli and cauliflower would develop flowers normally.

C.  broccoli would develop flowers normally, and cauliflower flowers would be arrested as buds.

D.  cauliflower would develop flowers normally, and broccoli flowers would be arrested as buds.





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 CAL gene?

 

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

C.  broccoli would develop flowers normally, and cauliflower flowers would be arrested as buds.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses the CAL gene.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
· What key words does the question contain and what do they mean?
        o The Brassica plant family includes the familiar vegetables broccoli, cauliflower, cabbage, kale, brussels sprouts, and others.
        o The CAL gene is involved in flower development.
 
Gather Content
· What do you already know about the CAL gene?
        o The CAL gene is involved in flower development.
        o The gene was first studied in Arabidopsis, where a mutation interferes with flower development, creating tiny “cauliflower”-looking bunches of undeveloped flower meristem.
        o It was then found that the CAL gene is, in fact, mutated with a STOP codon in both broccoli and cauliflower.
 
Consider Possibilities · Consider the different answer options. Which can you rule out?
        o If broccoli had a wild type CAL gene, and cauliflower had a mutant one, would both broccoli and cauliflower flowers be arrested as buds? No, because the wild type gene in broccoli would promote normal flower development.
        o If broccoli had a wild type CAL gene, and cauliflower had a mutant one, would both broccoli and cauliflower develop flowers normally? No, because the mutant gene in cauliflower could not promote normal flower development.
        o If broccoli had a wild type CAL gene, and cauliflower had a mutant one, would cauliflower develop flowers normally, and broccoli flowers be arrested as buds? No, the opposite, because the wild type gene promotes normal flower development.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o If broccoli had a wild type CAL gene, and cauliflower had a mutant one, would broccoli develop flowers normally, and cauliflower flowers be arrested as buds? Yes, that’s right. The wild type gene would promote normal flower development in broccoli, and the mutant gene in cauliflower would not.
 
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 phenotype you would expect if broccoli carried a non-mutated CAL gene.
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that both broccoli and cauliflower share the feature of excessive flower meristem development, and they share the same mutation in the CAL gene?
        o Did you realize that if broccoli didn’t have the mutation, it would be expected to have normal flower development?