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
Why would the limb structures of a frog and a human be so similar in shape and organization compared to the limb structures of a whale and bat?
A.
Both frogs and humans use their limbs in similar ways when gripping objects.
B.
Both frogs and humans evolved at the same time.
C.
Both frogs and ancestral humans moved on land using all of their limbs.
D.
Both frogs and humans derived from the same ancestors.
1 answer
The correct answer is:
D. Both frogs and humans derived from the same ancestors.
This answer reflects the concept of common descent in evolutionary biology, where similarities in limb structures among different species can be traced back to shared ancestral forms. While frogs and humans may use their limbs differently, their structural similarities suggest they have a common evolutionary origin.
