Flashcards
evolution
Cards in this deck (38)
- 1Evolutionthe scientific explanation for the mechanisms that drive species to change over time.
- 2fossil recordthe total number of fossils that have been discovered, as well as to the information derived from them
- 3The modern evolutionary synthesiscombines evidence from the fossil record with our relatively modern knowledge of how genes are inherited and how changes to genes arise to give a complete
picture of the mechanisms of evolution. - 4Continental Driftthe movement of the crustal plates that make up our landmasses. Over the eons, these plates have drifted apart, separating the organisms living on them.
Pangaea became Laurasia and Gondwanaland which then broke into the continents as we know them today. - 5FossilsFossils are any preserved evidence of organisms that once existed on Earth
Whole body of the organism
Evidence of its activity
Burrows
Tracks
Faeces (coprolite) - 6Palaeontologythe study of past life
- 7Conditions for fossilisationThe conditions at the bottom of the ocean, lakes or rivers are good for fossil formation. The sediments build up, drying occurs and sedimentary rock will form containing the fossil. You need:
Hard objects (teeth, bone, shells, wood)
To be covered quickly by a sediment
Low or no oxygen, and alkaline soils - 84 main types of fossiloriginal fossils
replacement fossils
carbon film fossils
indirect fossils - 9Original fossilWhen a part of the organism is preserved, with its chemical composition being much the same as it was when it was alive.
Example: Sea creatures that had hard shells (molluscs – scallops, clams mussels)
Vertebrates due to their bony skeleton and teeth - 10Replacement fossilsWhen a part of the organisms is chemically changed into another mineral.
Calcium carbonate converts into silica or silicon dioxide
The silica can then convert into opal
Trees that are turned into a stone like silica (petrified) is another example. - 11Carbon film fossils / Carbon trace fossilsWhen the dead organism decays and leaves a thin black deposit of carbon.
Plant fossils are the most common exampleThe shape and finer details of the organism can be preserved in this manner.
Coal is formed by this same process – although the shape and details of the organism is not retained - 12Indirect fossilsPreserved remains of the imprint of the body footprints, tracks, burrows and dung.
Common in aquatic fossils – molluscs, arthropods.
Casts occur when the organism in the rock decomposes, the space is filled with sediment that forms rock and forms a positive image or 3D model - 135 Preserving environmentsPermafrost
Amber
Tar
Peat
Dry Air - 14Permafrostin the Artic circle where the land is permanently frozen
Bacteria and fungi which are involved in decomposition, cannot survive. So the whole organism can be preserved - 15Ambersolid plant sap or gum
Small organisms (spiders, invertebrates, small vertebrates) get caught in the sticky sap from trees
Decomposition is stopped and the organism is perfectly preserved. - 16Tarwhere oil seeps out of the ground and onto the surface
Traps animals, prevents decomposition and allows for preservation
The best examples are the mammoths, bison and sabre-toothed cats - 17Peatpartially decomposed remains of plants and is found in swamps or bogs
No oxygen and bacteria can survive in peat so preservation of soft tissue is possible.
The acidic environment of the soil makes the bones very soft.
Great example – Tollund man - 18Dry AirDry Air
Bacteria and Fungi cannot live under very dry air conditions
The soft tissue dehydrates and then fossilises and forms a ‘mummy’
The mummy then forms a mould in sediments - 19GradualismThis suggests that evolution has occurred at a steady pace.
It accounts for sudden changes in the pace suggested by the appearance of fossils as due to environmental changes that didn’t allow many fossils to be laid down (or made it more possible) - 20Punctuated equilibriumThis suggests that the rate of evolution has changed. It suggests that evolution has proceeded at a rate determined by the environment which have caused new species to replace old.
- 21Absolute datesthe use of techniques that can assign a numerical age to a fossil or rock.
eg Radiometric dating - takes advantage of known rates of atomic decay
Electron spin resonance - electrons trapped in a material gain magnetic force over time.
Luminescence techniques - measure light emitted from a material - 22Relative dates (Comparative dating)an idea of how old a rock is in relation to surrounding rocks, since we know that sedimentary rock is formed by gradual deposition of sediments.
Lower rock is assumed to be older than rock that is higher. The rock may have tilted or even rotated, so this method requires careful observation. - 23Principle of superpositionLayers at the top are younger than the layers at the bottom
- 24Correlation of rock strataMatching of layers of rock from different areas
- 25Index fossilswidespread & present for limited time on Earth
- 26Fluorine Relative DatingMovement of fluoride ions in the water, in the soil, into the bone
All fossils in a particular deposit should contain the same amount of fluoride
The older the fossil the more fluoride it contains - 27Nitrogen Relative datingSimilar to fluorine, Nitrogen accumulates in a bone.
After death, this Nitrogen decays. Absolute dating not possible as many factors affect the rate at which it decays.
Such things as moisture temperature and other chemicals in the soil. - 28Absolute dating Potassium-Argon DatingDecay of radioactive potassium to form calcium & argon
Decay takes place at a slow rate
Determining amounts of K-40 and Ar-40 can determine age of rock
Limited
Can only date rocks older than 200,000 to 300,000 - 29Radiocarbon DatingGreen plants use CO2 one atom in every million million (1012) is C-14
Plant then eaten by animal becomes part of animal
Death – intake of C-14 stops but decay of C-14 continues at fixed rate - 30Tree Ring DatingConcentric rings on the surface of a cut tree
Each ring is one year
Rings width varies according to favourable conditions
Marker rings correlated with timber from ancient human structures - 31BiogeographyThe geographical distribution of species provides evidence that now isolated locations were once close.
The differences between species in different locations can give an indication of how much time has passed since they were co-located. - 32Divergent evolutionDivergence occurs as groups of organisms change over time, accumulating enough changes that they become different species. This usually happens when groups of a single species disperse to different environments which then become isolated, preventing individuals from moving between the groups.
- 33Convergent evolutionWhen different species evolve similar adaptations in response to similar environmental demands or opportunities, but don’t come from a common ancestor, this is convergent evolution.
An example of convergent evolution is the adaptation of ant-eating structures in ant-eating species. - 34analogous structuresstructures that have independently evolved to serve the same purpose but do not have the same structure. These may arise by convergent evolution.
- 35Embryologyis the comparative study of vertebrate embryos, which share similarities across a large range of species even with relatively distant common ancestors.
- 36Homologous structuresfeatures that were present in common ancestors and have evolved to perform different functions in descendent species.
- 37Vestigial structuresVestigial structures are homologous structures that no longer have a function in the descendent species.
An example is the human appendix.
the caecum that is found in the digestive tract of herbivorous primates.
The tiny pelvis and femur in whales.
Vestigial eyes of burrowing animals. - 38Biochemical EvidenceAll organisms have certain biochemicals in common.
All use DNA, ATP, and many identical or nearly identical enzymes.
Organisms use the same triplet code and the same 20 amino acids in proteins.
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- 00 bio Flashcards on evolution, created by aimee g on 13/07/2016.
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