Evolution Flashcards
What is the theory of evolution?
All of today’s species have evolved from simple life forms that first started to develop over three billion years ago
What did Darwin know?
Organisms in species show wide variation in their characteristics (phenotypic variation) bc of differences in genes + organisms have to complete for limited resources
What did Darwin conclude from his findings?
Organisms with most suitable characteristics for environment = most successful competitors & most likely to survive aka ‘Survival of the fittest’
What are successful organism that survive most likely to do?
Most likely to reproduce and pass on genes to offspring
What are organisms that less well adapted less likely to do?
Less likely to survive & reproduce + to pass genes on to next generation
Name 3 things that supported Darwin’s hypotheses
- Discovery of genetics
- Bacteria are becoming more resistant to antibiotics
- Fossils of different ages (fossil record)
Explain how the discovery of genetics supported Darwin’s hypothese
Provided explanation of how organisms born with beneficial characteristics can pass them on
Explain how bacteria being resistant to antibiotics supported Darwin’s hypothese
Bacteria are able to evolve to become resistant to antibiotics → support evolution by natural selection
Explain how the fossil record supported Darwin’s hypothese
Shows how changes in organisms developed slowly over time
Name 3 reasons why not everyone agreed with Darwin’s theory
- Went against common religious beliefs
- Darwin couldn’t explain why new, useful characteristics appeared or how they passed on
- There wasn’t enough evidence to convince many scientists
What is speciation?
The development of a new species
When does speciation occur?
Happens when populations of same species become so different → can no longer successfully interbreed to produce fertile offspring
How does speciation occur?
- Isolation - populations of species are separated due to physical barrier
- As environment is different on each side, each population shows genetic variation bc have wide range of alleles due to natural selection operating differently on population
- In each population, individuals with characteristics that
make them better adapted to their environment = have better chance of survival (so breed successfully) - Alleles that control beneficial characteristics are passed on to next generation
- Populations becomes so different that successful interbreeding is no longer possible = are separate species
What is extinction?
When no individuals of a species remain
Name 5 possible reasons for extinction
- Environment changes too quickly
- Catastrophic event happens that kills them all
- New disease kills them all
- A new predator kills them all
- Can’t complete with another (new) species for food
What are fossils?
Remains of dead plants and animals
How can fossils form? Name 3 ways
- From gradual replacement by minerals
- From casts and impressions
- From preservation in places where no decay happens
Give an example of fossils that created from gradual replacement by minerals
E.g. skeletons that have been replaced by minerals to become rock
Give an example of fossils that created from casts and impressions
E.g. outline of paw prints, burrows, etc
Give an example of fossils that created from preservation in places where no decay happens
E.g. preserved in ice
Why is the fossil record incomplete?
Geological activity & because some organisms don’t leave fossils
What did Lamark argue?
That the changes that an organism acquires during its lifetime will be passed on to its offspring
Explain what Lamark thought
Thought that if a characteristic was used a lot by an organism = it would be more developed during its lifetime and organism’s offspring would inherit the acquired characteristic
Define genetic variation
Different characteristics as a result of mutation or reproduction
