1. Which ofthe following is true of the evolution of cell membranes?

a) Aspopulations of organisms evolve, different properties of their cellmembranes are selected for or against.

c) Cellmembranes have stopped evolving now that they are fluidmosaics.

d) Theevolution of cell membranes is driven by the evolution ofglycoproteins and glycolipids.

e) Anindividual organism selects its preferred type of cell membrane forparticular functions.

2. One in hibitor of cGMP is Viagra. It provides a signal that leads to dilation of blood vessels and increase of blood in the penis,facilitating erection. cGMP is inhibited, therefore the signal isprolonged. The original signal that is now inhibited wouldhave:

a)phosphorylated GDP.

b)hydrolyzed GTP to GDP.

c) removedGMP from the cell.

d)hydrolyzed cGMP to GMP.