A Level Biology Practice Exam 2025 – All-in-One Study Guide to Excel in Your A Levels!

Organisms display similarities due to convergent evolution primarily by evolving similar traits in response to comparable selection pressures. This concept highlights how organisms from different evolutionary backgrounds can develop similar adaptations when faced with similar environmental challenges. For instance, both dolphins (mammals) and sharks (fish) have streamlined bodies and fins, which allow them to move efficiently in water, despite their different ancestral origins.

Identical DNA sequences are indicative of close evolutionary relationships, often seen in organisms that share a common ancestor, which is not the case here. Sharing a common ancestor would suggest divergent evolution, not convergence. Adapting to entirely different environments typically leads to distinct traits rather than the similarities seen in convergent evolution. Therefore, it is the response to comparable selection pressures that is key to understanding the similarities in traits observed in organisms that have not shared a recent common ancestor.