Many G protein-coupled receptors contain seven transmembrane α-helical domains. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior surface or on the cytosolic surface of the membrane. The loop on the cytosolic side between helices 5 and 6 is usually substantially longer than the others. Where would a coupled G protein most likely interact with this receptor?

#Question id: 9617

#Unit 9. Diversity of Life Forms

The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed 3-chambered hearts (2 atria, 1 ventricle). Birds and mammals, however, are alike in having 4-chambered hearts (2 atria, 2 ventricles). The 4-chambered hearts of birds and mammals are best described as

#Question id: 9618

#Unit 9. Diversity of Life Forms

Generally, within a lineage, the largest number of shared derived characters should be found among two organisms that are members of the same

#Question id: 9619

#Unit 9. Diversity of Life Forms

A common ancestor for both species C and E could be at position number 

#Question id: 9620

#Unit 9. Diversity of Life Forms

The two extant species that are most closely related to each other are

#Question id: 9621

#Unit 9. Diversity of Life Forms

If this evolutionary tree is an accurate depiction of relatedness, then which of the following should be correct?

1. The entire tree is based on maximum parsimony.

2. If all species depicted here make up a taxon, this taxon is monophyletic.

3. The last common ancestor of species B and C occurred more recently than the last common ancestor of species D and E.

4. Species A is the direct ancestor of both species B and species C.

5. The species present at position 3 is ancestral to C, D, and E

#Question id: 9622

#Unit 9. Diversity of Life Forms

Which of the following numbers represents a polyphyletic taxon?