Evidence that cell signaling evolved early in the history of life comes from __________.

• A. comparative studies of mitochondrial DNA
• B. comparative studies of ribosomal RNA
• C. the fossil record
• D. the study of protein receptors embedded in the nuclear membrane
• E. the similarity of cell-signaling mechanisms in organisms that have a very distant common ancestor

Answer: (E)

Verified step by step guidance

1. Understand that cell signaling is a fundamental process that allows cells to communicate with each other, which is crucial for the functioning of multicellular organisms.
2. Recognize that the question is asking for evidence of the early evolution of cell signaling mechanisms.
3. Consider that if cell signaling mechanisms are similar across a wide range of organisms, it suggests that these mechanisms were present in a common ancestor and have been conserved through evolution.
4. Note that the similarity of cell-signaling mechanisms in organisms with a very distant common ancestor indicates that these mechanisms evolved early and have been maintained due to their essential role in cellular communication.
5. Conclude that the correct evidence for the early evolution of cell signaling is the similarity of these mechanisms in diverse organisms, rather than specific studies of DNA, RNA, fossils, or nuclear membrane proteins.