B6.3 The development of understanding of genetics and evolution Flashcards
Who is credited with the theory of natural selection?
Charles Darwin.
How did he come to develop his theory?
The result of observations on a round the world expedition, backed by years of experimentation and discussion and linked to developing knowledge of geology and fossils.
Who contributed to the theory of evolution but is often forgotten?
Alfred Russel Wallace.
State the three steps in the theory of evolution by natural selection.
“1. Individual organisms within a particular species show a wide range of variation for a characteristic
- Individuals with characteristics most suited to the environment are more likely to survive to breed successfully
- The characteristics that have enabled these individuals to survive are then passed on to the next generation”
How was Darwin’s theory published and when?
In a book, “On the Origin of Species”, published in 1859.
State three reasons why Darwin’s ideas were only slowly accepted.
“1. The theory challenged the idea that God made all the animals and plants that live on Earth
- There was insufficient evidence at the time the theory was published to convince many scientists
- The mechanism of inheritance and variation was not known until 50 years after the theory was published”
What theory did Jean-Baptiste Lamarck propose?
The idea that changes that occur in an organism during its lifetime can be inherited.
Are his ideas now accepted in the scientific community?
Only in very rare cases do scientists believe this is the case.
Whose studies lent most evidence to the idea of speciation (the formation of a new species from a common ancestor)?
Alfred Russel Wallace.
What is a species?
A group of organisms that have similar physical, biochemical and behavioural features, can breed to create fertile offspring and do not usually breed with individuals of another species.
Give the six steps in the process of speciation.
“1. Geographical isolation (e.g. a flood divides an island in two)
- Different selection pressures/conditions in the new environments
- Genetic variation (due to mutations) within the groups
- Best adapted individuals to the new conditions survive, reproduce and pass on these alleles
- No interbreeding over time, groups become more different to each other
- After a large amount of time, unable to interbreed successfully. They are now separate species.”
Why are few fossils of early life found?
Most early life were soft-bodied and so left little trace behind.
What does the lack of fossils of early life on Earth mean about the theories scientists have on the beginning of life on Earth?
We can’t be certain about them as there is little evidence.
Why are fossils useful?
Can be used to determine how much or how little organisms have changed as life developed on Earth.
In evolutionary diagrams, what do junctions between the lines represent?
A common ancestor of two species
