Biology- Variation And Evolution Flashcards
1
Q
What is variation
A
The differences in the characteristics of an individual
2
Q
What is variation caused by
A
- the genes that individuals have inherited
- the conditions the individual has developed in
- a combination of the two
3
Q
How are new alleles created
A
Mutations
4
Q
What are mutations
A
- the permanent changes of the DNA in a cell
- they occur continuously in an organism at a low rate
- they often have no effect on the phenotype
- they’re often harmful but sometimes can be useful
5
Q
What is evolution
A
The gradual change in the inherited characteristics of a population over time
6
Q
What is the theory that is most supported by science
A
The theory of natural selection
7
Q
Who was this theory created by
A
Charles Darwin
8
Q
What is natural selection
A
It states that all species evolved from simple life forms that first developed over 3 billion years ago
9
Q
Why does it occur
A
- within a particular species, more individuals are born than can survive
- due to the difference in their genes, the individuals may show variations in their phenotypes
- individuals with phenotypes most suited to their surroundings are more likely to survive
- these individuals breed and these genes are passed on to their offspring
10
Q
How are fossils formed
A
- from the hard parts of the organism that hasn’t decomposed as easily
- as preserved traces of organisms (footprints)
- when parts of the organism are replaced by other materials
- if the organism was trapped in a place decay cannot take place (amber, peat bogs)
11
Q
Why are there gaps in the fossil records
A
- many early forms of life were soft bodied therefore they decayed completely
- traces may have been destroyed by geological activity
