When a ligand attaches to a receptor, which of the following occurs first? (consider a ligand to be a hormone or a cell messenger)
a) there is a change in shape of the ligand which causes the signaling cascade
b) there is a change in shape of the receptor which triggers the stopping of the signaling cascade
c) there is a change in shape of the receptor which triggers the beginning of the signaling cascade
d) there is a change in shape of the receptor which causes the ligand to be released

Which of the following is a period in the paleozoic era? devonian cambrian permian all of the above

The carrier molecules of the electron transport system are located in the

The table presents the average day and night temperatures in five cities. it also reveals whether a city receives substantial rainfall (wet climate) or little rainfall (dry climate). which city’s rocks are likeliest to experience frost wedging, and why? a) city a because the consistently subzero temperature would prevent water from melting b) city b because it is a wet region and the temperature fluctuates around the freezing point c) city c because it receives plenty of rain fall and the weather is moderately cool d) city d because the hot and dry weather would cause rocks to absorb water