the origin of species Flashcards
what was earth like 4 billion yearsa go
repeated bombardment brings water and destruction
strong young sun, high radiation at the surface
describe the deep sea 3.8 billion years ago
deep sea clefts in rock, two layers of water (acid and alkaline) meet each other
where did we get the energy (negative entropy) to form the first replicating molecles
the flow of protons may have provided the energy to fuel the first replicating molecules due to the proton gradient around the alkaline hydrothermal vents
which came first, rna or dna
RNA
how was rna used by life in the beginnning
as genetic material and as an enzyme
why was the rna world slow to come about
rna was slow to reproduce and was less able to act upon the environment back then
what came before and after rna
complex organic molecules produced by random chemistry to rna to proteins to DNA
what is the purpose of a cell for dna
to protect the dna molecules and keep them in close contact for reaction
where could life (rn reproducing) have arose (2)
in the tiny pores in rocks around vents
or in lipid protobionts which could reproduce by dividing
what conditions do we need for life
cool temperatures so as not to disintegrate molecules
gravity
water (as a solvent to bring molecules into contact)
protection from radiation
what caused the great oxidation event
cyanobacteria photosynthesised and produced oxygen which was consumed by methanogenic bacteria
however most of these methanogens died out due to changes in trace metals of the sea
what is theory for eukaryogenesis
an archaebacterium engulfed a heterotrophic eubacterium which eventually became mitochondria
how were chloroplasts formed
a second even where an autotrophic eubacteria was engulfed by a eukaryotic plant ancestor
what are opisthokonts
a broad group of eukaryotes that include both fungi and animals
how old are ediacarian biota
570mya
describe a spriggina
annelid worm or arthropod. kind of like a leaf
describe a dickinsonia
animal in origin, ate bacteria
describe a rangeomorph
branched, fern like, an animal
describe an erniettomorph
were modular/ quilted
when was the Cambrian explosion
540 to 515 million years ago
what does the burgess shale contain
preserved soft body fossils
why did the Cambrian explosion happen 4
physiological change
geographical change geochemical change
biological change
why would physiological change lead to the Cambrian explosion
increased the level of dissolved oxygen in the sea which meant a more active lifestyle
why would geographical change lead to the Cambrian explosion
new seas, new niches. the changing seas moved continents and shallower seas created new niches
why would geochemical change lead to the Cambrian explosion
increased availability of chemicals in the water due to glaciation. sea level changes led to abundance of tracemetals to make exoskeletons
why would biological change lead to the Cambrian explosion
increase in zooplankton led to new predators, increasing selection pressure
disappearance of dinosaurs led to
new niches (ecological species) for mammals and birds
the mass extinction at the end of the Permian 250mya allowed for (3)
diapsids which become dinosaurs
cartilaginous fishes
therapsids, our ancestor x
what may have caused the mass extinction at the end of the Permian 250mya
massive rapid climate change eg volcano, tectonic plates, asteroids
