Organisms are classified into three domains: Archaea, Bacteria, and Eukarya.
Scientists compared several molecular and cellular features across these three domains to determine their evolutionary relationships.
The table shows a comparison of some features of the three domains:
| Feature | Archaea | Bacteria | Eukarya |
|---|---|---|---|
| Histones associated with DNA | Present in some species | Absent | Present |
| Introns in genes | Present in some species | Absent | Present |
| Sensitivity to streptomycin/chloramphenicol | No | Yes | No |
| Chromosome structure | Circular | Circular | Linear |
| Membrane lipid hydrocarbon chain | Branched | Unbranched | Unbranched |
Explain what conclusions can be drawn from the table about which domains are most closely related.
State the roles of histones and ribosomes in cells.
22 exam-style questions on OCR A A Level Biology Classification and evolution. Each one has a worked solution and a mark scheme showing where the marks go.