Practice question · Multiple choice
The Last Universal Common Ancestor (LUCA) marks a genealogical bottleneck rather than the inception of biology. What follows from this distinction for our understanding of early evolution?
Hints
- What does the 'last' in LUCA imply about biological history that preceded it?
- Does a genealogical node indicate the very start of life, or merely the point of shared modern ancestry?
Show the answer
D. Independent lineages existed earlier but left no modern descendants
Why
Confusing LUCA with the origin of life ignores extinct pre-LUCA lineages. Molecular relics like ribozymes and the shared genetic code were already established by the time LUCA lived, rather than developing after divergence.
Practise The Origin of Life and the RNA World
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More questions on The Origin of Life and the RNA World
- Why does the RNA world hypothesis resolve the chicken-and-egg problem of DNA and protein?
- Place these stages of early molecular evolution in the order the RNA world hypothesis proposes.
- A hypothetical genetic code uses 4 bases and codons of length 2. How many distinct codons does it have?
- Which observations support the idea that RNA preceded DNA and protein?
- The genetic code is essentially the same in bacteria, plants and animals.
- Sort each molecule by the role the RNA world hypothesis assigns it in modern cells.