Biology Y9/10 Evolution, Speciation and Classification Flashcards
(28 cards)
what is variation
differences in characteristics between individuals within a population/species or between species
types of variation
- genetic variation
- environmental variation
- combination
examples of genetic variation
- eye colour
- sex
- blood group
examples of environmental variation
- accent
- veganism
- scarring
examples of combination variation
- mass
- skin colour
- flexibility
- fingerprints
what is evolution
the change in inherited characteristics in a population over time
what causes evolution
random mutations
what did all living things evolve from and when
simple life forms more than 3 billion years ago
how does natural selection occur
- variation is present within a population
- characteristics better suited to the environment are more likely to survive and reproduce
- alleles for advantageous characteristics are passed on to the next generation
potential advantages of natural selection
- can eat new foods
- resistance to new diseases
- run faster
- deter predators (e.g. producing chemicals)
- more sensitive hearing
what is artificial selection/selective breeding
the process by which humans breed plants or animals for desired genetic characteristics
what are desired characteristics in plants and animals for humans
- disease resistance for crops
- more milk/meat from animals
- better temperament
- larger/unusual flowers
how does selective breeding work
- select desired characteristics
- choose parents with those characteristics
- breed them
- select offspring with the desired characteristics
- breed them
- repeat until the whole population has the characteristics
advantages of artificial selection
- increased profit from increased yield
- fast
disadvantages of artificial selection
- can lead to inbreeding - more prone to diseases or inherited defects
what did Jean-Baptiste Lamarck believe
charactertistics could be acquired during an organism’s life in response to their environment, and could later be inherited
what was Charles Darwin’s theory
the theory of evolution by natural selection
why was Charles Darwin’s theory initially controversial
- challenged religious beliefs
- scientists tought there was insufficient evidence
- we didn’t know about genes + inheritance
what was Alfred Russell Wallace’s theory
the theory of evolution by naural selection (independently of Darwin)
how does speciation occur
- a population has natural genetic variation
- part of the population becomes isolated
- mutations occure randomly and spontaneously
- natural selection occurs independently, depending onthe environment
- genetic variation increses so that they can no longer interbreed
what are fossils
the remains of organisms from millions of years ago, fond in rocks
how can fossils form
- from parts of organisms that have not decayed because conditions needed were absent
- when parts of the organisms are replaced by minerals as they decay
- as preserved traces of organisms (e.g. footprints)
what do fossils show
how organisms have changed over time
how can we represent how organisms are related
with evolutionary trees
