Bio Exam 1 Tutorial 2

Tutorial 1 Bio Exam 1
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How old is Earth and how do we know?
4.55-4.56 billion years old. We know this because astronomers have done radiometric dating techniques on pristine meteorites
how old is the universe and how do we know?
the universe is 13.7 billion years old and we know this because astronomers have measured trajectories of the stars around us which are ever expanding
What chemicals were in early Earth's atmosphere and why was this beneficial to forming life?
Methane, ammonia, water vapor, and hydrogen. this was beneficial for life because the early atmosphere was highly reducing, meaning more electrons could be taken on and form more complex molecules
why would oxygen make life impossible in the beginning?
life could not arise from inorganic compunds if oxygen was present in the beginning because it would oxidize the inorganic material
What is the primordial soup model?
This model suggests that the origin of life arose from the right ratio of chemicals mixed together in a sort of "soup"
What was the Miller-Urey experiment?
This experiment simulated early earth by isolating hydrogen, ammonia, methane, and water vapor, and subjected it to an electrical charge. The result was a series of organic compounds, proving the primordial soup theory to be correct.
What were the first cells on Earth like?
autotrophs that gained energy from inorganic compounds like sulfur and iron compounds.

describe plate tectonics and their implications.
the fact that the Earth's crust is broken into pieces. the crashing/touching/rubbing of plates causes mountains, volcanoes, etc. to form. it also causes continental drift.
what is pangea and how many years ago did it exist?
Pangea was Earth's supercontinent that existed 250 million years ago. about 180 million years ago it began to break apart
what is the evidence for the existence of Pangea?

South America and African coastlines fit together
similar plant and animal fossils were found on the matching coastlines of SA and Africa
fossils of tropical plants found in Antarctica.
What are the four great eras of the geological time scale? (oldest to newest)
Precambrian, paleozoic (origin of most modern animal phyla), mesozoic, cenozoic (we are in the quaternary period of the cenozoic era)
What is relative dating?
when sedimentary rock forms, layers pile on top of layers. a layer is called a stratum. fossils are embedded in these stratum, and older fossils are embedded in deeper stratum. people estimate the relative date of a fossil based on the location of the layer where the fossil is found.
What is an isotope?
the same atom with a different number of neutrons.
describe radiometric dating.
radioactive isotopes decay into more stable elements at predictable rates. scientists use half life (the amount of time it takes for half of the unstable parent atoms to decay into stable daughter atoms) to date rocks and fossils
Describe radiocarbon dating. How many years have to go by before is it no longer accurate?
Carbon-14 decays into Nitrogen-14. Results are no longer valid after 50,000 years.
What is dendrochronology?
absolute dating technique. One ring is produced on a tree each year. by matching tree growth ring patterns with dead wood laying in the vicinity, a tree growth ring catalog has been created that spans back 9,000 years.
How many species have we documented on earth?

1.8 million documented species
What are the three domains of life and which ones are prokaryotic
bacteria, archaea, and eukaryotes. Bacteria and archaea are prokaryotic.
How many species to we estimate to exist on earth
between 10-100 million

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