Long answer question Flashcards
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What is one of the major “stepping stones” for life?
Transition from RNA to DNA
What is important about the switch from RNA to DNA?
more complicated cell structures and specialisation allowing greater adaption and self-replication.
What was a beneficial characteristic of some early forms of RNA?
Ability to catalyse and self replicate
What is one accepted hypothesis for the origins of life put forward by Miller and Urey? (1952)
“pre-biotic soup” with life originating around ocean edge getting needed energy from lightning strike
What apparatus did Miller and Urey use in their experiment?
Heat source over water
Flows past gas inlet of CH4, NH3
Passes into chamber with electrodes for spark
Cooled
What was produced in the Miller and Urey?
proteins structures necessary for forming life
When did the great oxidation event occur?
2.1 billion years ago start of the Proterozoic (American society for microbiology)
What is the driving factor of the GOE thought to be?
Cyanobacteria
When have cyanobacteria been present since?
~2.7 Ga (Leslie Orgel, 1994)
What was the cause for a lag between the presence of cyanobacteria and the GOE?
Adsorption of oxygen by Iron
What allowed for a build up of oxygen in the oceans and eventually diffuse into the atmosphere?
Abundance of cyanobacteria producing oxygen overcoming the sequestration rate
What did increased oxygen in the atmosphere mean for surface conditions?
Made more hospitable for terrestrialisation
What was the effect of the GOE on Earths atmopshere?
pre-event= mainly nitrogen and methane
Post-event= Methane replaced by Oxygen (N78 O21)
What is one of the key effects of having oxygen in the atmosphere for surface conditions?
Helped with production of ozone (O3) absorbing UV rays and reducing solar intensity on surface eventually producing ozone layer
When was the ozone layer formed?
600 Ma (University of Albany)
What is terrestrilisation?
The colonisation of land via freshwater habitats by plants and animals
What did Roman-Palacios et al, 2022 say about terrestrilisation?
Most terrestrial species have freshwater ancestors
When did terrestrialisation occur?
Middle Ordovician with cyanobacteria being the first but thought limited to moist environments (Wellman, 2010)
What is the first example of a land plant?
Rhyniophytes (Late Silurian to Devonian)
What does rhyniophytes look like?
curved thin stem with saucer on top (3 cm tall)
At what point do examples of the modern tree start to appear?
Late Devonian
What is the first example of modern tree development?
Progynosperms (middle to late Devonian)
What should a sketch of Progynosperms look like?
Tree with trunk and branches with dark leaf canopy 10m tall
Due to the development of larger tree species from the lower to upper Devonian what happened to substrate penetration?
transition from shallow penetration to deeper penetration as larger plants need a greater stabilising area and uptake for water and nutrients
What sketch can visualise the change in substrate penetration?
Algeo and Scheckler 1998
Sketch- minimal penetration to some vertical elongate to hexagon to deep extensive (with trunk above)
What is the effect of more extensive root systems?
greater weathering surface increasing pedogenesis
How are roots and carbon sequestration linked?
Roots increase weathering
Increased weathering of silica rich rocks which takes C from atmo and puts it as Calcium carbonate into water and soil
What was another result of increased pedogenesis?
increased sediment flow in fluvial systems
What was the effect of increased sediment and nutrient flow in fluvial systems?
Eutrophication
What is Eutrophication according to Nixon 2012?
an increase in organic matter in a system
What is the effect of eutrophication on earth systems?
evidnece that eutrophication lead to anoxia with bacteria using up oxygen decomposing matter
What past evidence is there for the effect of eutrophication?
OAEs - ocean anoxia events such as Kellwasser in the late Devonian
What is he evidence for OAEs?
black shales which indicate bottom water anoxia
What is an example of the effect of anoxia on distribution of species?
Belemnites deep to surface then spread
What is a benefit of photosynthesising plants on land?
Carbon sequestration into biosphere
How does the development of land habitats make areas more hospitable?
Sucession and colonisation cycle making abiotic less extreme
What does Berners Geocarb III show (1991)?
dramatic drop in atmo co2 linked to plant land colonisation
What is the culmination of tree developemnt?
Aborescene which was a period of mass wood production
What is the main thing from Cambrian explosion?
major phyla
What evolution dominated early Cambrian?
calcium carbonate shells and biomineralization
What is the significance of biomineralisation?
carbon sink (limestone)
How was diversity affected by Cambrian explosion?
huge jump - benthic to pelagic
What was the substrate revolution? (Bottjer et al, 2001)
from edicaran to soupier substrate allowing for bilaterian burrows
How is the burgess shale konservat lagerstatte evidence of cambrian diversification? (Royal Ontario Museum)
anomalocaris which was apex predator originally thought to be 2 seperate species
What proxy can be used to look at predation? (sperling 2013)
Link between uranium oxygen and predation
More oxygen more predation
What is an opposing idea to Sperlings oxygen predation?
Geobiology issue 7 volume 1
Oceanic ventallation
stratified cyano to ventilated eukaryotic
What is one of the earliest example of biomineralisation?
Cloudina (Ediacaran)
What us cloudina like?
tube like funnel external skeleton of metazoan
How does biomineralization affect the atmo and hydro reservoirs of carbon?
oceans absorb 25% of atmo carbon (UN climate) so if biomineralisers remove C from water more can be absorbed
How did plant colonisation of land affect the landscape?
braided rivers with little vegetation
Meandering with dense vegetation due to increased stability
What is the introduction for the earth history long answer?
Life has evolved through the history of Earth. As a result of evolutionary change there has also been an environmental change brought about by evolution organisms have affected the conditions of the environment with noticeable impacts on the atmosphere, hydrosphere, and terrestrial realm.
What is the conclusion for the earth history long answer?
The evolution of life on Earth has had a very influential effect on the environment and conditions on a global scale. The presence and change of life have affected both the physical landscape and the composition of both the oceans and atmosphere through time. Without the presence of life conditions on Earth would be different from those at present.
What order am I talking about ideas in my long answer?
Intro
Miller Urey
RNA/DNA
Photosynthesis (cyano)
Oxygen in atmo/ GOE
Trees/Roots
Habitats due to trees
Eutrophication (belemnites, OAEs)
Cambrian explosion
Substrate revolution
Biomineralisation
Conclusion
How can the substrate revolution put forward by Bottjer et al 2000 be visualised?
By Mangano and Buatois (2014)
Show translation from eidacaran predominantly surface with none in substrate or column
To Cambrian stage 3 lots of vertical and horizontal burrows and anomalocaris
