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what is evolution
the gradual change of species over time
describe the steps of natural selection (4)
organisms in a species show variation caused by a difference in genes
organisms with characteristics that are best adapted to their environment survive and reproduce - survival of the fittest
genes from successful organisms pass onto offspring so offspring are more likely to have advantageous characteristics
the process is repeated over many generations till a new species is developed
explain the evolution of peppered moths (5)
peppered moths that are usually white show variation caused by a mutation that makes them black
moths with the mutation are best adapted to their environment as trees turned black from soot so they were camouflaged
this means they were more likely to survive and reproduce - survival of the fittest
the gene from successful black moths pass onto offspring so offspring are more likely to have the advantageous characteristic
the process is repeated over many generations till black moths became more common
what are fossils
animal and plant remains that are preserved in rock
what is the fossil record
fossil layers that form a sequence and show how an organism has gradually changed over time
how are fossils formed (4)
the reptile dies and falls to the ground
the flesh rots leaving the skeleton to be covered in soil/clay/sand
skeleton mineralises and turns into rock
fossil emerges as rocks move and erosion takes place
what three pieces of evidence does the fossil record give us
fossils of simple organisms are found in older rock, showing simple life has evolved into complex life
plant fossils are in older rock, showing animals needed plants to survive
closely related organisms have evolved from a common ancestor
why are there gaps in the fossil record (2)
some organisms decompose too quick
fossils are destroyed e.g. by volcanoes
what other evidence for evolution is there (3)
rapid changes in a species like bacteria
species that don’t adapt go extinct
closely related species have similar DNA
what observation did darwin make
finches on different islands had different types of beaks
what conclusion did darwin make that he called natural selection
a bird with a suitable beak for the food on its island survives and passes on the beak to offspring until they all held this characteristic
why was darwin’s discovery controversial
it went against the idea that god created all life
why is darwin’s theory widely accepted nowadays
fossil record, dna studies and extinction are proof
what is classification
the process of sorting living organisms with similar characteristics into groups
what three reasons do scientists classify organisms for
to identify species
to predict characteristics
to find evolutionary links
what are the 7 taxonomic levels
kingdom
phylum
class
order
family
genus
species
what are the 5 kingdoms
animals, plants, fungi, prokaryotes, protoctista
what is a species
a group of organisms that can reproduce to produce fertile offspring
what is artificial classification
grouping organisms together based off of observable characteristics that don’t take evolutionary links into account
what is phylogeny
the study of evolutionary links
what is natural classification
using common ancestors to link organisms
how are phylogenic links made
by studying similarities in DNA between species. the more similar they are, the closer the species are related.
