Question

During chordate evolution, what is the sequence (from earliest to most recent) in which the following structures arose? 1. amniotic egg 2. paired fins 3. jaws 4. swim bladder 5. four-chambered heart

A) 2, 3, 4, 1, 5
B) 3, 2, 4, 1, 5
C) 3, 2, 1, 4, 5
D) 2, 1, 4, 3, 5
E) 2, 4, 3, 1, 5

Answer 1

The sequence of structures that arose during chordate evolution, from earliest to most recent, is paired fins, jaws, swim bladder, amniotic egg, and four-chambered heart which is option A) 2, 3, 4, 1, 5.

Step-by-step explanation:

You asked about the sequence in which certain structures arose during chordate evolution. To determine the order from earliest to most recent, we look at the evolutionary timeline and the key innovations in chordate development. Evidence suggests that paired fins (2) developed early on to help organisms maneuver in the water, followed by jaws (3), which allowed for a wider variety of feeding strategies and were a significant evolutionary step for gnathostomes. Afterward, we see the evolution of the swim bladder (4), which aided in buoyancy control for fishes. The amniotic egg (1) came later, allowing for reproduction on land, a major milestone for terrestrial vertebrates. Lastly, the four-chambered heart (5) evolved in birds and mammals, signifying a more advanced circulatory system. Thus, the correct sequence is 2, 3, 4, 1, 5, which corresponds to answer choice A).