B14 - Variation and evolution

Question 1

What is variation

Answer 1

Differences in the characteristics in a population

Question 2

What causes variation

Answer 2

Differences in:
the genes that have inherited (genetic causes)
the conditions in which they have developed (environmental causes)
a combination of genes and the environment

Question 3

What does sexual reproduction produce

Answer 3

Different combinations of alleles and therefore variation, but only mutations create new alleles

Question 4

What do mutations do

Answer 4

Mutations happen continuously
Rarely they will lead to a new phenotype
If the new phenotype is suited to the environment it can lead to a rapid change in the species

Question 5

What is evolution

Answer 5

It is the gradual change in the inherited characteristics of a population over time
This can lead to a new species

Question 6

What is the theory of evolution

Answer 6

It is called natural selection
Created by Charles Darwin
It states that all species have evolved from simple life forms that first developed more than 3 billion years ago

Question 7

What has evolution by natural selection caused

Answer 7

Organisms produce lots of offspring
Individual offspring will show a wide range of variations and a new mutations can result in a new phenotype
All organisms in the population will compete e.g. food, shelter, mates
Individuals with characteristics most suited to the environment are more likely to survive to breed successfully
The alleles that have allowed these organisms to survive are then passed onto their offspring
Over long periods of time the characteristics of population change