Figure 1 depicts the limbs of a human, lizard, cat, whale, bat, frog, and bird. The different bones in each limb are shaded and labeled using the human arm as a key. Figure 2 is a cladogram representing the evolutionary links between organisms.
Figure 1
From left to right, the illustration shows the forearm of a human, a lizard, a cat, a whale, a bat, a frog, and a bird. The human forearm is labeled from top to bottom, humerus, ulna, radius, and carpal. Each forearm bone is a different color. The finger bones are numbered, from left to right, 5, 4, 3, 2, 1, except the bird, which has three finger bones numbered, from left to right, 3, 2, 1. Whales have the shortest humerus, ulna, radius, and fifth finger bones compared to the other organisms shown. In Bats, the Humerus and Radius bones are very thin, and they do not have an ulna bone. Bat finger bones are elongated with pointed sharp ends. Frogs and bats have the shortest first finger bone. Bats and birds have the least number of carpal bones compared to the other organisms shown. Cat finger bones are packed closely together, whereas they are apart in the other organisms.
Figure 2
From bottom to top, the cladogram's origin is labeled 'Four limbs evolved'. This line branches into two main lines. The left main line splits into two and are labeled 'Bat' and 'mouse' respectively. The right branch of the main line splits into two and are labeled 'Bird' and 'Lizard' respectively.
Multiple Choice Question
Although birds and bats have a similar forearm, their wings are quite different. A bird wing is covered in feathers that are attached to the arm. A bat wing is made from skin that is attached to the arm and between each finger bone. The graphic shows the two wing types.
The left illustration shows a bat wing with an arrow labeled 'skin' pointing to the middle of the wing. The right illustration shows a bird wing with an arrow labeled 'feathers' pointing to the middle of the wing.
Which option best describes the evolution of these features of bats and birds?
A.
The forearms of birds and bats are similar in structure, so this feature did not come from a common ancestor. The wings of birds and bats are not similar in structure so this feature came from a common ancestor.
B.
The forearms of birds and bats are similar in structure, so this feature came from a common ancestor. The wings of birds and bats are not similar in structure so this feature did not come from a common ancestor.
C.
The forearms of birds and bats are similar in function, so this feature came from a common ancestor. The wings of birds and bats are not similar in function so this feature did not come from a common ancestor.
D.
The forearms of birds and bats are not similar in function, so this feature did not come from a common ancestor. The wings of birds and bats are similar in function so this feature came from a common ancestor.
1 answer
The correct answer is:
B. The forearms of birds and bats are similar in structure, so this feature came from a common ancestor. The wings of birds and bats are not similar in structure so this feature did not come from a common ancestor.
Explanation:
- The forearms of birds and bats share a similar bone structure (humerus, radius, and ulna), indicating they likely evolved from a common ancestor.
- However, the wings themselves are constructed differently: bird wings have feathers while bat wings consist of skin stretched between elongated finger bones. This indicates that the wings evolved independently and are examples of convergent evolution rather than being derived from a common ancestor.
