They have different sizes and shapes. An example would be a tomato and a grape. Tomatoes are red, grapes are purple/green. Grapes are small, tomatoes (most of them) are large. This must be because the cells that make the tomatoes differ from the one that makes the grapes. Hope this helped/made sense :)
C) slate, a metamorphic rock
To connect skeletal muscles to bones.
The bald eagle and the black bear are tetrapods, which means that they both have four limbs along with the digits. This shows that they both are the descendants of the four-limbed ancestors. However, the limbs of the bear and the bald eagle have different functions. The forelimbs of both these organisms serves different purpose. Hence, their limbs are homologous organs. The homologous organs are those which have the same ancestry but the functions are different.
Yes they did. It is generally known that amphibians breathe through their skin.