Comparative Anatomy

INTRODUCTION: We have learned this year that DNA controls our genes which controls how we are formed, i.e. out traits. This means that organisms with similarly built structures, even though theyperform different tasks, must have some common DNA which controls the formation of that structure. Structures that are built the same but which may have different functions are called homologousstructures. HOMOLOGOUS STRUCTURES LINK
1. Here is a picture of the bones of the forelimb (front leg if you wish) of a human a cat, a whale and a bat. What is the main function of each forelimb?
* Ahuman uses its forelimb to grasp things, to push, to pull, to eat, and to write. A cat uses it to protect themselves such as scratching and to jump and hold into things. A whale uses its forelimb topropel or push itself in the water. A batb uses it to fly.
2. The first bone near the shoulder is called the humerus. How many does each animal have?
* All the animals have one humorous bonenear the shoulder.
3. The next two bones are called the radius and ulna. How many does each animal have? Notice the numerous “wrist” bones. Count the fingers or digits. How many digits does eachanimal have?
* Each animal has one radius, one ulna, and five digits or fingers.
4. Refer back to the video you watched at the beginning. I speaks about divergent evolution. Explain the termdivergent evolution using the phrase common ancestor. What does divergent evolution tell us?
* Divergent evolution tells us that animals that have homologous structure have similar bonestructures because they have evolved from a common ancestor millions of years ago.
5. LETS TEST EVOLUTON AGAIN; Hypothesis If bats, cats, whales and humans are all mammals and have a common ancestor,then if I check out their body parts, like a forelimb (front leg) I predict that I should see some similar pattern. Does evolution stand up to this testable hypothesis?
* Evolution supports this...