evolution, fossils, speciation & classification (paper 2) TOPIC 6 Flashcards
what is evolution
a change in the inherited characteristics of a population over time through the process of natural selection, which may relate in the formation of a new species
what is the theory of evolution by natural selection
all species of living things have evolved from simpl life forms that first developed more than three billion years ago
why does evolution actually happen
natural selection of varients that give rise to phenotypes best suited to their environment
when has a new species formed
when two populations of one species become so different in phenotype that they can no longer interbreen to produce FERTILE offspring
who invented the theory of evolution
charles darwin
when do scientists think early life forms developed on earth
more than 3 billion years ago
what did people believe about life on earth before evolution
that God created everything
other than darwin, who else had a theory of evolution
Lamarck
describe Lamarck’s theory of evolution
every type of animal evolved from worms and the change to other orgaisms was casued by the inheritance of acquired characteristics - giraffes used their neck a lot so it grew longer
what were the problems with Lamarck’s theory
- not enough evidence
- people didn’t like the idea of desccending frfom worms
- could see it wasnt true in humans
where did darwin discover evolution through natural selection
on the galapagous islands from the variety of finches from island to island
what process did darwin suggest
natural selection
explain darwin’s theory of natural selection
- individula organisms within a species show a wide ranger of variation for a characteristic
- mutation gives rise to new variants
- individuals with characteristic most suited are more likely to survive and breed successfully
- these characteristics are passed onto the next generation
- this occurs over many generations
what was darwin’s book called
On the Origin of Species (1859)
why was the theory of evolution by natural selection only gradually accepted
- theory challenged idea that God made life on earth
- insufficent evidence at the time
- mechanism of inheritance and variation was not know until 50 years after the theory was published
how has bacteria evolved
become antibiotic resistant
how have bacteria had time to evolve
because bacteria reproduce at a very fast rate
how does antibiotic resistant bacteria occur
- there is variation in the population of bacteria
- mutations occur naturally and spontaneously
- mutations occur in the bacteria
- this produces new stains of bacteria
- some strains are resistant to anitbiotics
how has bacteria become resistant to antibiotics
- overuse of antibiotics
- patients not completing course of medicine = can mutate
- argicultural use of bacteria in animals even when not ill
why is it important to reduce the rate of development of antibiotic resistant stains
the development of new anitbiotics is expensive and slow and unlikely to keep up with hte emergence of new resistant strains
what are fossils
remains of plants and animals from millions of years ago
who created the theory of speciation
Alfred Wallace
what is speciation
the development of new species when populations of the same species become so different that they can no longer successfully interbreed to produce fetile offspring
what two factors lead to speciation
- isolation
- natural selection
describe the process of speciation
- any population contains a wide range of alleles
- in each population alleles are advantegous to help the organism survive (natural selection)
- sometimes part of a population is isolated because of new environmental conditions
- alleles will be selected for each of the populations in the new environments
- this increases variation more between the population
- evutally the populations become so different they cannot reproduce successfully and are two different species
how might a population become isolated
- new mountain range
- new river
- area of land becomes an island
- earthquake splits land
- volcanoes porduce new land
how old are fossils
millions of years old
where are fossils found
in rocks
what are the three ways fossils can have formed
- from parts of organisms tha thave not decayed becuase one or more conditions needed were absent
- when parts of the organism are replaced by minerals as they decay (mineralisation)
- as preserved traces of footprints (footprints, burrows, roots)
what is mineralisation
when parts of the organism are replaced by minerals as they decay
why are there only few traces of early life forms
because they were soft-bodied which means that what traces that were, have been destroyed by geological activity
why are there gaps in the fossil records
- many of the earliest life forms were soft bodied and therefore left very few traces
- most fossils have been destroyed by geological activity
- most oragnisms that die do not fossilise
- not all of them have been found yet
why can scientists not be sure about how life began on earth
because there are too many gaps in fossil records as he earliest life forms were soft-bodied and left few traces
what can we learn from fossils
how much or how little different organisms have changed as life developed on earth
define extinction
the permanent loss of all the members of a species
what might extinction be caused by
- changed to the environment
- new predators
- new diseases
- new more successful competitors
- a single catastrophic event
what is mass extinction
the loss of many species at the same time
what is classification
organisation of living things into groups according to their similararities
suggest why biologists classify organisms
- make it easier to study them
- make sense of the living world
- understand how different groups of organisms are related
- recognise the biodiversity on earth
- gives scientists a common language
who proposed the idea of clasification
carl linnaus
what are the groups of classification
- domain
- kingdom
- phylum
- class
- order
- family
- genus
- species
(do keep penis’ clean or forget good sex)
in the binomial system how many words are the names given to each organism
2
describe the formations of the names in the binomial system
- 1st name = genus = capital letter
- 2nd name = species = lower case
- write in italics
in 1970s what idea did Carl Woese introduce
a higher level called a domain
how many types of domains are there
3
what are the three domains
- archaea
- bacteria
- eukaryota
what type of things are in the archaea domain
early forms of bacteria that include ectremophiles, organisms that can live in extreme conditions; this contains one kingdom, the archaebacteria
what type of things are in the bacteria domain
these are the true bacteria and cyanobacteria, bacteria-like organisms that can photosynthesise; this contains one kingdom, the eubacteria
what type of things are in the eukaryota domain
these are all have cells that contain a nucleus enclosing the genetic material; there are four kingdoms - the protista, fungi, plants and animals
how many kingdoms are there
6
name the kingdoms
- protista
- fungi
- plants
- animals
- archaebacteria
- eubacteria
what are evolution trees
a method used by scientists to show how they believe organisms are related
what do evolution trees show
- common accestors
- relationships between species
