chapters 25,26,27,28 Flashcards
What are the four stages of chemical evolution leading to life?
1) Abiotic synthesis of organic molecules, 2) Abiotic synthesis of polymers, 3) Formation of protobionts, 4) Self-replicating RNA
Why is RNA considered the first genetic material?
RNA can store genetic info and act as a catalyst (ribozyme), allowing self-replication.
What is radiometric dating?
A method to determine absolute age using the ratio of radioactive isotopes to their decay products.
How do index fossils help determine relative age?
They are widespread, short-lived species used to correlate rock layers and estimate relative age.
What was Earth like before 2 billion years ago?
Hostile environment, prokaryotic life only, oxygen began accumulating due to photosynthesis.
Name one life form from each era since 600 MYA.
Paleozoic – trilobites; Mesozoic – dinosaurs; Cenozoic – mammals.
What caused the Permian extinction?
Volcanic eruptions → global warming → ocean anoxia → ~96% marine life extinct.
What caused the Cretaceous extinction?
Likely asteroid impact → dust blocked sun → mass extinction (including dinosaurs).
What is the Snowball Earth hypothesis?
Earth was largely frozen during the late Proterozoic, limiting diversity and distribution.
Why is the Cambrian Explosion significant?
It marks a rapid diversification of animal body plans and major phyla.
How does continental drift promote speciation?
Geographic isolation leads to divergent evolution.
What is adaptive radiation?
Rapid evolution of many diverse species from a common ancestor in a new environment.
Give an example of adaptive radiation.
Galápagos finches evolved varied beaks to exploit different food sources.
Define heterochrony.
Evolutionary change in the rate or timing of developmental events.
Define paedomorphosis.
Retention of juvenile traits in the adult form.
What are evolutionary novelties?
New structures or functions that provide advantages (e.g., wings, eyes).
What are Hox genes?
Master regulatory genes controlling body plan development in animals.
What is phylogeny?
The evolutionary history of a species or group.
What is systematics?
The science of classifying organisms and reconstructing evolutionary relationships.
List the taxonomic levels from most to least inclusive.
Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species
Define clade.
A group including an ancestor and all its descendants (monophyletic group).
What is the difference between homologous and analogous traits?
Homologous: same ancestry, may have different function; Analogous: same function, evolved independently.
What is the function of the sex pilus?
Transfers DNA between bacteria during conjugation.
What is the nucleoid?
Region in prokaryotes containing the chromosome.
