Segments of DNA that contain the code for specific proteins are called genes
Answer:
Cycles in predator/prey populations.
Explanation:
Climate change, decrease of keystone species and the introduction of new species all contribute to instability of the ecosystem.
The first vertebrates appeared in the Paleozoic Era, specifically the Cambrian period. The vertebrates were <span>jawless fish with backbones made out of cartilages. It was thought that the first fishes evolved during this period. The correct answer to this question is letter "A. Cambrian". I hope this helps.</span>
