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

Click an item in the list or group of pictures at the bottom of the problem and, holding the button down, drag it into the correct position in the answer box. release your mouse button when the item is place. if you change your mind, drag the item to the trashcan. click the trashcan to clear all your answers. label the following topographic map. click on a label below the map to select it, and then click on the appropriate box on the map to place the label. (increments for contour lines is 50 ft).

Consider the skeleton. which skeletal system is represented by the shaded portion of the skeleton? spongy skeleton compact skeleton axial skeleton appendicular skeleton

Which must be kept in mind when determining if an explanation is correct? check all that apply.which must be kept in mind when determining if an explanation is correct? check all that apply.