Evolution

Question 1

What were Lamarck’s theory’s two key idead

Answer 1

• a characteristic which is used more and more by an organism becomes bigger and stronger, and one that is not used eventually disappears
• any feature of an organism that is improved through use is passed to its offspring

Question 2

How can Lamarck’s ideas be proved wrong

Answer 2

simple organisms still exist, which according to him would’ve disappeared as all organisms become complex

Question 3

What did Lamarck’s theory about giraffes

Answer 3

• necks elongated as ancestors stretched their necks to reach higher branches to eat
• this became a useful characteristic and was passed on to future generations, increasing the length of their necks over time
• however we now know mutations caused variation in neck length and then we use Darwin’s ideas to support this

Question 4

Describe Darwin’s theory of natural selection

Answer 4

• Individual organisms within a particular species show a wide range of variation for a characteristic
• individuals with characteristics most suited to the environments are more likely to survive and breed successfully
• the characteristics that have enabled these individuals to survive are then passed on to the next generation

Question 5

What idea did Darwin’s theories challenge

Answer 5

that God made all the animals and plants on Earth

Question 6

Other than challenging creationism, why did ‘On the Origin of Species’ spark controversy in Victorian Society

Answer 6

there was insufficient evidence when 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

Question 7

what was Wallace’s theory called

Answer 7

Speciation

Question 8

what is a species

Answer 8

a group of organisms able to interbreed and produce fertile offspring

Question 9

4 ways new species can arise

Answer 9

1) genetic variation - each population has a wide range of alleles that can control their characteristics
2) natural selection - the alleles which help an organism to survive are selected in each population
3) speciation - the populations become extremely varied and successful interbreeding cannot happen anymore
4) isolation

Question 10

what is isolation

Answer 10

• 2 populations of a species become geographically separated because of the environment
• isolation can prevent interbreeding and the combination of genes within a species
• different mutations can take place in the isolated groups and create different phenotypes within a particular location
• over time speicies may evolve to be different to each other, and they will not be able to interbreed