B15 - Genetics And Evolution Flashcards
Gregor Mendel’s discovery
He found that some traits could be hidden within a generation, leading to the discovery of dominant and recessive alleles
He used different coloured pea plants to do this
Evolution
The gradual change of a species characteristics
Speciation
The formation of new species
The process of speciation
A population becomes geographically isolated from the original population (rivers)
They are now different environmental conditions in the new population
Mutations can occur causing variation
Natural selection occurs, whereby the best adapted individuals survive and reproduce
The new population eventually changes to the point where it can no longer inbreed with the old population
Charles Darwin’s theory of evolution
All species of living things have evolved from simple life forms that first developed
Why was Charles Darwin’s theory initially rejected?
Not enough fossil evidence
Inheritance and genes where not known at the time
Why is Charles Darwin’s theory now accepted?
Better technology
Characteristics were found to be passed down
Knowledge of antibiotic resistance
Jean-Baptiste Lamarck theory of evolution
He proposed that the way an organism behaved affected their features – if they used something a lot over time,
this feature would grow and develop
Fossil
The remains of an organisms that lived in the past found preserved in rock
Formation of fossils (frozen)
The organisms body is frozen to preserve its body
Formation of fossils (footprint)
A footprint fossil show the characteristics of the animal
Formation of fossils (skeletal)
The organism dies and gets covered by mud
The organs of the organism decay
The skeletal system of the organism is left
The mud surrounding the organism becomes a rock
The rock mineralises
Conditions for decaying
No oxygen
Heat
Why don’t we have a complete fossil record?
Early organisms had soft bodies (no skeletal system)
Fossils may have been destroyed
Fossils have not been found
Reasons for extinction
The animals could not adapt to their new surroundings or environment
