If asked to find the cause of regular fluctuations in a population's size not associated with seasonal environmental variation, you would probably first seek evidence for: 

#Question id: 1232

#Unit 4. Cell Communication and Cell Signaling

Which of the following mutations might confer a competitive advantage to an athlete by raising his or her hematocrit?

a. excess production of erythropoietin                       

b. decreased production of erythropoietin

c. EpoR that cannot bind STAT5                  

d. EpoR that cannot bind SHP1

e. EpoR that cannot bind JAK2

#Question id: 1233

#Unit 4. Cell Communication and Cell Signaling

Transphosphorylation (cross-phosphorylation) of receptor tyrosine kinases

a. inhibits catalytic activity.

b. promotes transphosphorylation of additional tyrosine residues.

c. triggers release of the ligand.

d. generates binding sites for signaling molecules.

#Question id: 1234

#Unit 4. Cell Communication and Cell Signaling

Which of the following mutations would likely have a similar cancer-promoting effect as the RasD mutation?

a. mutation in Grb2 so that it cannot bind Sos

b. mutation in Sos so that it binds Ras independent of Grb2

c. mutation in GAP so that it cannot bind Ras

d. mutation in EGF receptor so that it binds GRB2 independent of EGF

#Question id: 1235

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the EGF signal:

a. transphosphorylation of the EGF receptor

b. dissociation of GDP from Ras                   

c. dissociation of Ras from Sos         

d. binding of GRB2 to the EGF receptor      

e. binding of GTP to Ras  

#Question id: 1236

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the TNF-α signal

a. phosphorylation of I-κB                 

b. binding of E3 ubiquitin ligase to I-κB       

c. polyubiquitination of I-κB             

d. nuclear localization of NF-κB       

e. activation of TAK1 kinase

#Question id: 1237

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the Notch/Delta signaling pathway:

a. cleavage of Notch by TACE                                  

b. binding of Delta to Notch

c. translocation of Notch segment to the nucleus      

d. interaction of Notch with transcription factors     

e. cleavage of Notch by Presenilin 1