#Question id: 28213
#Unit 5. Developmental Biology
Specification of different mesodermal cell types in the frog Xenopus laevis by activin, a paracrine factor of the TGF-beta family. Which of the following observation is correct at the high concentration of activin?
#Question id: 15987
#Unit 12. Applied Biology
#Question id: 19876
#Unit 13. Methods in Biology
#Question id: 4987
#Unit 11. Evolution and Behavior
A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island, and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species each of which eats only a certain type of food. None of the species can fly, for their flight wings are absent, and their balancing organs (i.e., halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap.In each fly species, the entire body segment that gave rise to the original flight wings is missing. The mutation(s) that led to the flightless condition could have
#Question id: 28692
#Unit 2. Cellular Organization