A Researcher Inactivates Lefty1,a Gene Expressed in the Anterior Visceral

question 2

Multiple Choice

A researcher inactivates Lefty1,a gene expressed in the anterior visceral endoderm of the mouse.What effect would inactivation of this gene have on the gastrula-stage embryo?

• A) The epiblast becomes abnormally thickened throughout its cranial-caudal extent.
• B) The primitive streak fails to form.
• C) The endoderm fails to form.
• D) The neural plate fails to form.
• E) Extra primitive streaks form.

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Definitions:

Hypothetical Syllogism

A logical argument that has two premises followed by a conclusion, each of which is a conditional statement.

Categorical

Pertaining to categorization or the division of something into distinct categories.

Quantity Words

Words that express amounts of items or describe the extent of something, such as "many," "few," "several," etc.

Hypothetical Conclusion

A conclusion that is based on a conditional statement, depending largely on a "if-then" scenario.