Fossils of Thrinaxodon, a species that lived during the Triassic period, have been found in both South Africa and Antarctica. Thrinaxodon had a reptile-like skeleton and laid eggs, but small depressions on the front of its skull suggest it had whiskers and, therefore, fur. Thrinaxodon may have been warm-blooded. The fossils of Thrinaxodon are consistent with the hypothesis that ________.

#Question id: 1127

#Unit 4. Cell Communication and Cell Signaling

Which of the following steps does not occur after acetylcholine binds to the muscarinic acetylcholine receptor in heart muscle cells?

#Question id: 1128

#Unit 4. Cell Communication and Cell Signaling

During the epinephrine stimulated conversion of glycogen to glucose 1-phosphate, which of the following steps involves protein phosphorylation?

a. inactivation of glycogen synthase               b. activation of protein kinase A

c. activation of adenylyl cyclise                      d. activation of glycogen phosphorylase

#Question id: 1129

#Unit 4. Cell Communication and Cell Signaling

Which of the following plays a role in the relaxation of smooth muscle cells by nitric oxide?

a. cGMP          b. protein kinase A      c. protein kinase G      d. guanylyl cyclise

#Question id: 1130

#Unit 4. Cell Communication and Cell Signaling

In muscle cells, glycogen phosphorylase kinase is activated by

a. Ca2+.           b. diacylglycerol.   c. nitric oxide.       d. protein kinase A.    

#Question id: 1131

#Unit 4. Cell Communication and Cell Signaling

Which of the following function(s) as an inhibitor of TGFβ signal transduction?

a. R-Smad       b. I-Smad        c. Co-Smad     d. Ski   e. SnoN

#Question id: 1132

#Unit 4. Cell Communication and Cell Signaling

Which of the following become(s) active as a kinase when an activation lip residue is phosphorylated?

a. EpoR                       b. JAK             c. STAT           d. Ras              e. MAPK