In early mammalian development:

Dahlia has an external female phenotype, but finds out later in life that she has XY chromosomes. An MRI reveals the presence of undescended testes. Which of the following is a genetic change that could have caused this phenotype? If needed, consult the model for gonadal sex determination in mammals below. A black arrow means that the activity of one member is enhanced by another (for example, Wnt4 enhances Beta-catenin activity). A red line with a perpendicular line at the end means that the activity of one member is inhibited by another (for example, Beta-catenin inhibits Sox9 activity). 

Is developmental biology equivalent to the study of embryos?

Q: Match each motor protein with its primary cytoskeletal track and function.  

Which of the following best describes the primary function of the ubiquitin–proteasome system?

Lucas is a post-doctoral researcher investigating the role of ALFA signaling in lung development. Alfa5 mRNA expression occurs in mouse lungs around day 15 of development. However, when previous researchers created a “knockout” Alfa5 mouse, it only survived until 9 days of development, prior to when lungs form. A heterozygous Alfa5 mouse exhibited completely normal development. Therefore, Lucas decided he wanted to reduce Alfa5 expression in another way, to find out what the impact of this would be on lung development. The signaling molecule “TOYOTA” is a known inhibitor of ALFA5. Therefore, Lucas engineered a mouse that makes MORE TOYOTA protein than normal, because this would presumably reduce the level of Alfa5 expression. This is an example of:

Consider the Sonic hedgehog (SHH) signaling pathway depicted below. What would happen to this pathway if, due to a mutation, the protein Smoothened was unable to travel into the primary cilium, even when SHH ligand is present?

Good model organisms often (check all that apply):

Match the life cycle stage description with its name:

Different cell types in a multicellular organism have different morphologies primarily because: