Carl Woese's three-domain system of classification revised the traditional kingdom model based on molecular and genetic analysis.
a.[2]
Which two of the following taxonomic groups are classified as domains in Woese’s system? Tick (✓\checkmark✓) two boxes.
- Animalia
- Bacteria
- Archaea
- Protoctista
- Plantae
b.[2]
Fossils provide direct evidence of how ancient life forms have changed over millions of years.
Define the term fossil.
c.[1]
The fossil shown in the diagram above is a trilobite, an ancient marine arthropod with a hard exoskeleton. How was this type of fossil formed? Tick (✓\checkmark✓) one box.
- The soft internal organs decayed and left a carbon imprint on the seabed.
- The hard exoskeleton was preserved intact by being trapped in tree resin (amber).
- Mineral ions replaced the hard parts of the exoskeleton over millions of years.
d.[2]
Trilobites flourished in the oceans for over 250 million years before going extinct. State two factors that could cause a species to go extinct.