history of life Flashcards
name the five kingdoms
bacteria ,protista, fungi, plantae and animalia
the 4 questions scientists tried to work out
- did this diverse range of living organisms develope on earth at the same time or did they develope in a sequence
- if they developed in a sequence ,when was this , and how did it take place
- if they develpoed in a sequence what was the sequence ? was it kingdom by kingdom
- what was the caurses of diversification
what dis scientists think of earth between 4-6 billion years ago
they thought that there was little to no oxygen on primitive earth
how did the absence of oxygen affect the earth
the absence of oxygen allowed the gasses present in the atmosphere at the time to form organic molecules such as fatty acids and protein which is the building blocks of living organisms
what is the first formed life forms
it is the prokaryotes ,like some present day bacteria
when di the prokaryotes develop
it developed about 3.5 billion years ago
what does anaerobic mean
it means that the prokaryotes did not require oxygen for their activities . they could release energy from their food supply without the use of oxygen
when did different bacteria’s begin to develop
between 3.5 and 2.5 billion years ago
name one of the bacteria that began to develop
blue -green bacteria (cyanobacteria )
what is the function of blue -green bacteria
the function is to manufacture food by the process of photosynthesis , during photosynthesis carbon dioxide is taken in and oxygen is released
what is aerobic
living organisms that depend on oxygen to release energy from their food
when did aerobic organisms develop
they developed as more oxygen was collected in earths atmosphere
what do scientists believe about the absence of oxygen
they believe that it led to the creation of life itself
what do scientists believe about the increase of oxygen
they believe that the increase of oxygen levels led to an increase in the diversity of living organisms
define ice age
ice age i long periods of time when the earth experienced extremely cold whether
what are the four ice ages that was identified since the time earth was formed
700 million years ago
320 million years ago
286 million years ago
the current ice age , which began slightly less than 3 million years ago
what are glaciers
large sheets of ice
what is glaciantion
the process of the formation of large sheets of ice
when are glaciers formed
during the ice age
what caused large scale of extinction of life forms
glaciation and the sudden cooling that it brought about
what is continental drift
the changing position if the continents
plate tectonics
upward movement of continental blocks
what was responsible for glaciation
continental drift and plate tectonics and the reduction of carbon dioxide in the atmosphere and changes in the earths orbit also played part
what is the main theory that scientists use to explain the formation of glaciers
continental drift
what is pangea
when all the continents were originally one big mass or a super continent
how many years ago did it break into two large masses
225-200 million years ago
what were the two large masses called and where were they found
Laurasia in the northern hemisphere and Gondwanaland in the southern hemisphere
Gondwanaland broke to form ……..
south America
Africa
Madagascar
Australia
India
antarctica
laurasia broke into
north america
europe
the middle east
asia
china
what does the continental drift say about antarctica
is says that antarctica was once closer to the equator with a temperature climate where there was lush , swampy vegetation
what evidence is there that antarctica was once closer to the equator
there was a discovery of coal deposits coming from fossils of tropical plants in antarctica
how did this antarctica theory cause the formation of glaciers
as this large mass drifted towards the south pole , it caused rapid cooling and formation of large masses of ice . the lower temperatures resulted in the mass extinction of many life forms
when did the first mass extinction occur
approximately 438 million years ago was associated with a long period of rapid glaciation
define biography
refers to a study of the past and present distribution of individual species
what do scientists use geographical structures and identical plants and animal species
they use it as proof that the two continents was once joined
give an example of the geographical evidence that was found
similarities between the species found in Madagascar and these found in the east coast of Africa suggest that these two land masses were once joined
explain the plate tectonic theory
the earth is made up of about a dozen large plates which fit together like a jig saw puzzle . the plates lie on the top of much hotter materials which allow the plates to move apart even to this day
what can plate movements cause
upward movements of large continetal blocks
over the past 15 million years how many meters on average have the continents risen
600 metres on average
what do scientists say about the upward movement of the continental blocks
they are responsible for the climate changes that have led to the extreme cold periods of ice ages
what do scientists believe about the volcanic activity
they say that the volcano was the main cause of the three greatest mass extinctions since all three occurred during times of very serious volcanic activity
how did volcanoes cause the death of life forms
volcanic eruptions threw up huge clouds of rocks and lava and these would have brought about the sudden death of life forms of the time
what are fossils
remains of ancient life forms preserved in rocks although fossils have been found in ice , tar and the dried sap of trees
what is the study of fossils called
paleontology
what are ammonites
they are coiled molluscs which swam and floated in the sea . they are marine
to which group does the ammonites belong
to the same group as the octopus
do ammonites still exist
no , they are extinct . they became extinct about 67 million years ago
what are trilobites
they are marine arthropods distantly related to lobsters and crabs
when did trilobites becomes extinct
250 million years ago
what are bivalves
they are marine molluscs which have two shells which are mirror images , hinged together at one end so that they can open and close like two
name a present day bivalve
scallops
name a marine mammal
whales
where have fossils of ammonites and bivalves been found
in the makhatini flats in northern kwa zulu natal
where have fossils of trilobites been found
in the karoo and the whale fossils where found in the sahara
what does the finding of these fossils in these places mean
the presence of marine fossils in the parts of the earth which thes fossils where found ( parts of the kwa zulu natal , parts of the karoo ,and parts of the sahara ) indicates that thes where once covered by one sea
