History of Life on Earth Flashcards
Where did life arise on Earth?
hypothermal vents in the oceans
When did life arise on Earth?
4 billion years ago
How did life arise on Earth
volcanic eruptions contributed ammonia, methane, hydrogen, and water vapour to atmosphere. the water vapour condenses to oceans. UV radiation or lightening led to the formation of small organic molecules in the ocean
proton gradients that exist in the hypothermal vents as a source of energy
all of this led to LUCA. You go from having protocells to having a bunch of things that are kinda cells. bu only one of them is the LUCA
The miller Urey experiment
Stimulated earths early atmosphere and oceans.
In the presence of electricity they observed the formation of amino acids
nucleotides can spontaneously link together to form nucleic acids. the earliest molecules self assembled from small building blocks
How did protocells form?
lipids can self organize and form vesicles. the constant environment inside vesicles may have facilitated the formation of protocols
these protocols likely contain RNA as genetic material. Under the early conditions on earth, DNA probably formed from the RNA
Primordial soup
a theory that describes the conditions on early Earth that led to the evolution of life.
RNA can also act as an
enzyme
in the ancient world, ran also acted as an enzyme
origin of life
- Volcanic eruptions
- protocells
Oldest fossils
Photosynthesis evolves
Eukaryotic cells evolve
multicellular organisms
abundant fossils of aquatic life
first land plants
first land animals
insects
first mammals
dinosaurs
first birds
first flowering plants
rise of mammals
humans
What are the notable events in the precambrian era?
formation of earth
first oceans
origin of life
origin of photosynthesis
first colonial cyanobacteria
first eukaryotes
first photosynthetic eukaryotes
first multicellular eukaryotes
first fossils of multicellular animals
This all happened billions of years ago
the Phanerozoic era follows the precambrian era
What era were the dinosaurs alive in?
the mesozoic era
What is geology?
a science that deals with the history of the earth and its life, especially as recorded in the rocks
A major source of information about species of the past is from fossils. When is an organism most likely ot become a fossil? And how exactly are fossils used to date species?
An organism is most likely to become a fossil if its dead body is deposited in an environment that lacks oxygen.
Fossils are present in a layer of rock. Geologists can study the rock and determine its age. Therefore, they can estimate the age of the fossil
How do we determine the age of a rock layer?
Radioactivity provides a way to date rocks. Radioactive isotopes decay in a predictable pattern over long periods of time
Isotopes differ in the number of
neutrons
What is half-life?
The time it takes for half of a radioactive isotope to decay
Each radioisotope has a characteristic half life. Based on the amount of radioactive isotope remaining in the rock, we can determine how long the radioactive element has existed in the rock
Another way of determining the age of the fossil is not related to studying the rock. What is this alternate method?
using carbon isotopes and looking at the actual organism not the rock
The ratio of C-14 to C-12 is relatively constant in the environment and living organisms. In dead organisms, decaying C-14 is no longer replenished and ratio of C-14 to C-12 decreases over time
What are the four big physical things that have changed over time if we look at the planet as a whole?
- O2 levels
- Sea levels
- Climate
- Continental drift(location and number)
What causes major physical changes on earth?
- Volcanic eruptions
- Meteorite impacts
Atmospheric oxygen concentrations have changed over time. When did the first spike in oxygen occur? What events followed after that?
First photosynthetic cyanobacteria prompted the first spike in the amount of oxygen
Events following:
- First aerobic bacteria
- first eukaryotes
- first multicellular eukaryotes
- first chordates
- invasion of alnd
- giant flying insects
- first flowering plants
Dip in sea level often coincides with
a period of increased glaciation
periods of Cold and dry climate correlated with
ice age
Changes in climate affect
the survival of various types of species. These changes are associated with mass extinctions
True or false: mass extinction have only occurred twice in the history of the earth
False
Many of the groups of muilticellular organisms alive today first appeared during the __________(1), an evolution radiation that occurred during the time of the giant ___________(2) known as donna.
(1) cambrian explosion
(2) Gondwana
reptiles arose in the permian period, during the existence of the giant continent known as
Pangea
This permian period(and the entire paleozoic era) ended with massive volcanic eruptions. Explain two ways in which these eruptions led to a mass extinction event.
conditions for life deteriorated
- ash and gases blocked sunlight and cooled the plantet
- the decay of forest led to a rapid drop of oxygen levels
- most of Pangea was also in the souther pole of the earth
In the time of the dinosaurs, were the contents similar to those we have now?
No, supercontinents existed. Specifically Laurasia and Gondwana
evidence: similar species in tow different continents tells us that at one point they were geographically closer to each other and evolved together before continent split
What caused the extinction of the dinosaurs?
meteorite
dust and debris preventing sunlight and chilling the earth
prevents photosynthesis from occurring–> drop in O2
When continental plates collide, they sometimes cause volcanic eruptions or the formation of
mountains
Didd the formation of the earth happen billions or millions of years ago?
Billions
Didd the first life on earth happen billions or millions of years ago?
Billions
Didd the Cambrian explosion happen billions or millions of years ago?
Millions
did the time of the dinosaurs happen billions or millions of years ago?
Millions
Mass extinctions occurred in what periods?
Ordovician, Devonian, Permian, Triassic, and Cretaceous periods.
what is an ice age?
massive glaciers spread across the continent
Anthropocene
a geological epoch starting in the mid 20th century in which Earth has been radically altered by human impacts(due to climate change, availability of habitat)
