#Question id: 11012
#Unit 7. System Physiology – Animal
If the Purkinje fibers, situated distal to the A-V junction, become the pacemaker of the heart, what is the expected heart rate?
#Question id: 8296
#Unit 9. Diversity of Life Forms
Giardia intestinalis can cause disease in several different mammalian species, including humans. Giardia organisms (G. intestinalis) that infect humans are similar morphologically to those that infect other mammals, thus they have been considered a single species. However, G. intestinalis has been divided into different subgroups based on their host and a few other characteristics. In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species. The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G. intestinalis and a few other morphologically distinct species of Giardia. The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species.
According to the phylogenetic tree in the figure above, G. intestinalis constitutes a ________ group.
#Question id: 4618
#Unit 11. Evolution and Behavior
Which of the following observations helped Darwin shape his concept of descent with modification?
#Question id: 3455
#Unit 11. Evolution and Behavior
A duck egg is removed from its mother’s nest and incubated by a barnyard hen. The duckling hatches out in the presence of the barnyard hen and stays in her nest. After a couple of days, the duckling is presented with a choice between its biological mother and the hen that incubated it. The duckling approaches and follows the hen. This set of observations demonstrates the phenomenon of
#Question id: 1288
#Unit 4. Cell Communication and Cell Signaling
Which extracellular matrix component is expressed in a cell-specific manner and binds to the tripeptide sequence Arg-Gly-Asp?