Petrels (a flying and diving seabird) are thought to be one of the closest living relatives to penguins. What type of genes would be most likely to exhibit different expression patterns between these species?

Question

A.  Genes controlling skeletal development.
B.  Genes regulating the digestive tract.
C.  Genes regulating salt water tolerance.
D.  Genes controlling organ development.

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 gene expression patterns?  
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.  Genes controlling skeletal development.


Clarify Question
· What is the key concept addressed by the question?
        o This question addresses gene expression.
· 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 Gene expression patterns refer to how a gene is transcribed: where (in the body), when (during development) and at what level.

Gather Content
· What do you already know about gene expression patterns?
        o Gene expression refers to the amount of gene product produced in different times and places in the developing animal.
        o Gene expression is the key to understanding why different organisms end up looking different.
        o The best explanation for why a mouse develops into a mouse and not a human is that the same or similar genes are expressed at different times, in different tissues, and in different amounts and combinations.
 
Consider Possibilities · Consider the different answer options. Which can you rule out?
        o Is there likely to be a big difference in expression for genes regulating the digestive tract? Probably not since they have a similar diet– both petrels and penguins eat fish and other sea life.
        o Is there likely to be a big difference in expression for genes regulating salt water tolerance? Not likely, since both live in the marine environment.
        o Is there likely to be a big difference in expression for genes controlling organ development? No, there is no reason to think the organs are particularly specialized between the birds.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Is there likely to be a big difference in expression for genes controlling skeletal development? Yes. The wings, legs, and other bones of a penguin have become very different from the flying ancestor similar to a petrel.
 
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 type of genes were most likely to have different expression patterns in a penguin versus a petrel.  
        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 skeleton is one of the most different features between a petrel and a penguin?