If a Drosophila mother is mutant for dorsal, her embryos would
A. develop normally.
B. have a delay in the development of dorsal/ventral polarity.
C. lack dorsal structures.
D. lack ventral structures.
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 dorsal?
Consider Possibilities · What other information is related to the question? Which information is most useful?
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?
D. lack ventral structures.
Clarify Question
· What is the key concept addressed by the question?
o This question addresses dorsal.
· 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 Drosophila melanogaster is the species of fruit fly used in genetics research.
o The gene dorsal specifies ventral development in the Drosophila embryo.
Gather Content
· What do you already know about dorsal?
o The dorsal–ventral axis is established by actions of the dorsal gene product.
o Maternal transcripts of the dorsal gene are put into the oocyte, but the dorsal mRNA does not become asymmetrically localized.
o Following fertilization, a signaling molecule is differentially activated on the ventral surface of the embryo.
o Activation of this pathway results in the selected transport of the Dorsal protein (which is everywhere) into ventral nuclei, forming a gradient along the D/V axis.
o The Dorsal protein levels are highest in the nuclei of ventral cells.
Consider Possibilities · What other information is related to the question? Which information is most useful?
o Note that many Drosophila genes are named for the mutant phenotype that results from a loss of function in that gene.
o A lack of dorsal function produces dorsalized embryos with no ventral structures.
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o Will a lack of dorsal result in a lack of ventral structures? Yes, because the role of dorsal is to specify ventral structures.
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 result from a maternal mutation in the gene dorsal.
o The question required you to take what you already know and apply it to this unfamiliar situation.
o Did you recognize that despite the name, dorsal actually specifies ventral development?
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Unlike sweet, salty, sour, or umami, the "bitter" category of tastants includes wide structural variety of detected molecules. Multiple receptors are required to sense the different bitter tastants. What do they have in common? Bitter taste is thought to have evolved as a warning system for toxic compounds. A. They will not easily digest turnips and broccoli. B. They will have to eat more turnips and broccoli to get the same flavor. C. They will dislike turnips and broccoli. D. They will become allergic to turnips and broccoli. 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 taste receptors? 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?
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