Based on evolutionary relationships, which of the following is considered the more likely ancestor to eukaryotic cells?

• A. Archaea
• B. Bacteria
• C. Cyanobacteria
• D. Fungi

Answer: (A)

Verified step by step guidance

1. Understand the question: The problem is asking which group is considered the most likely ancestor to eukaryotic cells based on evolutionary relationships. This requires knowledge of the evolutionary tree of life and the characteristics of the groups listed.
2. Review the characteristics of each group: Archaea are prokaryotic organisms that share some similarities with eukaryotes, such as certain genetic and metabolic pathways. Bacteria are also prokaryotic but differ significantly from eukaryotes in their cellular structure. Cyanobacteria are a type of bacteria known for photosynthesis. Fungi are eukaryotic organisms and cannot be ancestors to eukaryotic cells because they are already part of the eukaryotic domain.
3. Recall the evolutionary relationship: Eukaryotic cells are thought to have evolved through a process called endosymbiosis, where an ancestral prokaryotic cell engulfed other prokaryotic cells, leading to the development of organelles like mitochondria and chloroplasts. The host cell in this process is believed to have been an archaeal cell.
4. Connect the evidence: Molecular and genetic studies have shown that eukaryotic cells share more similarities in their genetic machinery (e.g., DNA replication, transcription, and translation) with Archaea than with Bacteria or Cyanobacteria. This supports the idea that Archaea are the more likely ancestors.
5. Conclude the reasoning: Based on the evolutionary evidence and the shared characteristics between Archaea and eukaryotes, the correct answer is Archaea.