What is one main difference between the cell wall and the cell membrane?
a the cell wall is more fragile than the cell membrane.
b cell walls are only found surrounding animal cells.
c the cell wall is more rigid than the cell membrane.
d cell membranes are only found surrounding plant cells.

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .