Earth's History Flashcards
How old is Earth?
Earth is approximately 4.5 billion years old
What is macroevolution?
Macroevolution is evolution seen over a large time scale
Describe the atmosphere of early earth
Early earth had a reducing atmosphere devoid of oxygen. The following molecules were found:
- CO2
- CH4
- NH3
- H2S
- H2
As earth cooled, much of the H2 escaped into space and the water vapor that was present condensed into oceans
What is the Miller-Urey experiment?
The Miller-Urey experiment:
- Created laboratory conditions of early earth
- Mixture of H2, NH3, CH4, and water were placed in a reactive chamber. A spark hit this mixture to simulate lightning.
- Within several days, many amino acids and organic compounds were found
NB for DAT: The experiment showed that abiotic synthesis of organic materials is possible. Nucleotides were not produced.
What are the two key properties needed for life to exist?
Life needs two key properties:
- Metabolism
- Replication Mechanism
What are protobionts?
Protobionts are accumulations of organic material (molecule aggregates)
- Many appeared to have a membrane like structure surrounding it. This may have allowed the formation of a separate internal environment to have been created
- Lab experiments show that these protobionts can spontaneously form from abiotically produced organic molecules
What are liposomes?
Liposomes are a combination of organic material and lipids
- The liposome has an aqueous core surrounded by a lipid bilayer
- These can form simple metabolic reactions
- These can form spontaneously from abiotically created organic materials
What are ribozymes?
Ribozymes are RNA enzymes that:
- Can catalyze specific biochemical reactions
- Can act in a similar fashion as protein enzymes
- Able to replicate themselves
- First genetic material
What is the flow for the creation of life?
Inorganic molecules -> Organic Molecules -> Protobionts -> Prokaryotes -> Eukaryotes
What is the fossil record?
The fossil record is the sequence in which fossils have accumulated in the sedimentary rock layers (strata)
- It shows a series of organisms through time
- Its biased towards the most abundant animals.
What is radiometric dating?
Radiometric dating is the dating of rocks and fossils using radioactive decay
- C-14 for bones
- U-238 for rocks
What is the geologic record?
The geologic record is the division of our planets history into time periods.
What are the three main time periods of the geologic record?
The three main time periods of the geologic record are:
- Cenozoic: Most recent. Age of the mammals
- Mesozoic: Age of the reptiles
- Paleozoic: Fish first appeared, land plants followed, animals moved to land too.
These time periods are further subdivided. The only one to know is the jurassic period, which occurred during the Mesozoic Era.
What distinct event happened during the end of the Paleozoic era?
During the end of the Paleozoic era, a mass extinction event occurred that wiped out about 90% of all marine animal species. The exact cause is hotly debated
What is significant about the jurrasic period?
During the jurassic period of the mesozoic era, dinosaurs became the dominant terrestrial vertebrate. It occupied this position for 135 million years.
