Chapter 18: Origin & History of Life Flashcards
(26 cards)
4 stages of life origin?
Organic molecules → polymers → membranes → self-replication.
Protocell structure?
Lipid membrane around molecules.
Chemical vs biological evolution?
Chemical = molecules forming. Biological = cells evolving.
Relative vs absolute dating?
Relative = fossil order. Absolute = actual age.
Endosymbiotic theory?
Mitochondria/chloroplasts came from engulfed bacteria.
When did multicellular life appear?
About 600 million years ago.
Earth’s periods in order?
Precambrian → Paleozoic → Mesozoic → Cenozoic.
What is plate tectonics?
Earth’s crust moves, causes drift.
What is continental drift?
Continents shift over time.
Mass extinctions—causes?
Volcanoes, meteor strikes, climate change.
What is LUCA?
Last Universal Common Ancestor; the first common ancestor of all life.
Shared origin of all cells.
What are biomolecules?
Molecules needed for life, such as carbohydrates and proteins.
Examples include DNA, protein, fat.
What is abiogenesis?
The process of life arising from non-living matter.
Example: Molecules forming cells.
What is the primordial soup hypothesis?
The theory that life began in the early Earth’s oceans.
Example: Molecules formed in water pools.
What is the iron-sulfur world hypothesis?
The idea that life formed at underwater volcanoes.
Example: Reactions near hydrothermal vents.
What is the protein-first hypothesis?
The theory that proteins formed before DNA or RNA.
Example: Enzymes were the first life step.
What is the RNA-first hypothesis?
The concept that RNA was the first genetic material.
Example: RNA stored and copied information.
What is relative dating?
Determining fossil age by comparing layers.
Example: This fossil is older than that one.
What is absolute dating?
Determining fossil age with exact years.
Example: Carbon dating shows fossil is 5,000 years old.
What is radiocarbon dating?
A method that uses carbon-14 to date fossils.
Example: Used on bones and wood.
What are index fossils?
Fossils of known age used to date rocks.
Example: Trilobites from the Paleozoic era.
What is the geologic timescale?
A timeline of Earth’s history divided into time periods.
Example: Mesozoic = age of reptiles.
What is mass extinction?
A rapid loss of many species.
Example: Dinosaur extinction event.
What is plate tectonics?
The theory that Earth’s crust moves in plates.
Example: Earthquakes and mountains.
