History of life Flashcards
indirect methods of dating
- relative dating
- paleomagnetic dating
- fauna compositions
- dendrochronological
direct methods of dating
- radiometric dating ( absolute method)
- based on the tempo of radioactive decay
- ratio of different isotopes
relative dating
using the rock layers below and above fossils as an indication of age
paleomagnetic dating
magnetic components in rock are arranged in a certain orientation due to earths magnetic piles, tempo at which poles change can be compared with the orientation
fauna composition
fossils found in between layers of volcanic rock
dendrochronological
age of trees can be determined by its annual tongs which can be used to make deductions about what happened in its past including climate conditions
archaea bacteria
the most primitive form of life, unicellular prokaryotic (no nucleus)
habitat archaea bacteria are found in
- hot volcanic areas
- warm water spouts in deep sea
- areas of little/no oxygen
- high salinity water
eubacteria
developed from archaea bacteria
lynn margulis
-developed the theory of origin
-archaea bacteria hijacked the eubacteria
-eubacteria became part of cell becoming the mitochondria providing energy while getting food and shelter from the hijacker
parasitic relationship
a single cell organism resides within another cell
endosymbiosis
A symbiotic relationship where one organism lives inside the other
fossils
- remains of organisms that lived previously and were conserved, did not decompose and their whole/parts of remained intact
how are fossils formed
- organism dies where it can be covered with sediment
- anaerobic conditions prevent decomposition
- quickly covered with sediment
- hard body parts are slowly replaced by minerals
- or the body dissolved leaving only an impression of the natural form
- cavity of mould can be filled with minerals
- whole organisms can be kept intact eg amber
body fossils
fossilisation of whole organisms or body part
form fossils
sediment hardens around the organism and the organism dissolves
mould fossils
cavity is filled with minerals
trace fossils
marks made by an animal as it walked over sediment that later hardened
unchanged fossils
perfectly preserved organisms
why are fossils important
- trends in biodiversity
- evolutionary relationships
- formation of sediments
- exploration of economically important minerals
causes of mass extinction ( intrinsic factors)
- ice ages
- continental drift
- volcanic activity
- killer disease
ice ages
- atmospheric cooling
- formation of glaciers: drop in ocean levels
-higher salt concentration - less O2 available
continental drift
- separation of continents - different environments and not able to adapt quick enough
- plate movements cause cooling of temperatures (resulting in formation of glaciers and ice ages)
- changes in available habitat
- increased volcanic activity
volcanic activity
- clouds of volcanic matter block out sun rays, lack of light and solar radiation causing rapid cooling
- trapping water in ice caps
- photosynthesis could not take place collapsing in food webs
- sulphur dioxide increased acid rain
- carbon dioxide caused greenhouse effects and global warming increased
killer disease
- climate change can affect presence and spread disease
- viral/bacterial infections can kill large no. of organisms
extraterrestrial
- meteorites and asteroids
- physical damage
- tsunamis
- volcanic eruptions
intrinsic factors that have been caused by extrinsic factors
physical damage
- dust sand and gases
- block sky light affect food chains
- sulphuric acid rain poisons plants and aquatic organisms
- low temperatures make it hard for cold blooded animals
5 main mass extinctions
(earliest to latest)
1 - Cretaceous
2 - Triassic
3 - Permian (largest)
4 - Devonian
5 - orodovician
