Class 11 Quiz

1. This picture illustrates the evolution of whale. 55 million years ago, Mesonychid was a mammal that lived on land. Its four limbs allowed it to walk and hunt for prey. Ambulocetus evolved from Mesonychid. The structure of its head is flatter and its mouth was longer and sharper. The limbs of Ambulocetus adapted to amphibian environment that it was able to go to near land area yet still hunt in the water. The eyes of Ambulocetus were on the sides so that they can see better in the water. Rodhocetus evolved from Ambulocetus. The body structure of Rodhocetus was more streamlined, allowing it to swim in water. Its tail was divided into two parts to balance the body while swimming. The limbs changed to fins because fingers were not needed in water. Finally, Basilosaurus evolved from Rodhocetus. The structure of the body was more streamlined. All four of the fins grew smaller. The tail was longer so it can swim faster.

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3. All three of the organisms have wings that enable them to fly. However, bats have finger structure in the wings, while birds only have one single limb in the wing and dragon fly almost none. The limbs of birds are more stronger than bats and dragonfly so that they can stand on their feet. The neck of bird is long so it allows the bird to pick up its prey and food from the ground. The bat has a short neck and the dragonfly does not have a long one either. The long tail of dragonfly allows it to balance its body while the bat and the bird don't need long tails.

4. The sequences of Cytochrome C of different organisms demonstrate the relationship between them. The fewer differences between two organisms, the more closer they are to the common ancestor because DNA mutations take place over time. The less time available for mutations to happen, the closer two organisms are to their more recent common ancestor. Between human and Rhesus monkey, there was only 1 difference in amino acid number. Therefore, human and Rhesus monkey are very closely related.

5. Homology provides the relationship between a pair of structures or genes that have the common ancestor. For example, modern toothed whale and rodhocetus have the same tail structures. Furthermore, Tiktaalik share some common traits with fish, such as streamlined body structure.