theory of evolution

Question 1

what is darwin’s theory?

Answer 1

theory of evolution by natural selection

Question 2

what lead to darwin’s theory?

Answer 2

observations on a round the world expedition, backed by years of experimentation and discussion and linked to developing knowledge of geology and fossils

Question 3

what 3 things did his theory state?

Answer 3

• 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.

Question 4

where did darwin publish his ideas?

Answer 4

in his book On the Origin of Species (1859)

Question 5

were his ideas accepted?

Answer 5

no there was a lot of controversy

Question 6

why was his theory only gradually accepted?

Answer 6

• 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.

Question 7

what was larmack’s theory?

Answer 7

changes that occur in an organism during its lifetime can be inherited

Question 8

describe larmack’s theory in relation to giraffes

Answer 8

• Giraffes started with short necks adapted to lower vegetation.
• They stretched their necks to reach higher branches for food, resulting in longer necks during an individual’s lifetime.
• This acquired longer neck trait was passed to offspring, and successive generations have longer necks for reaching higher branches.

Question 9

why was larmack’s theory proven incorrect?

Answer 9

by genetics - we know that characteristics acquired by an organism during its lifetime do not affect the DNA sequence of the organism, and therefore cannot be passed down from one generation to the next

Question 10

describe darwin’s theory in relation to giraffes

Answer 10

• Some giraffes had longer necks than others, due to variation within the species.
• Giraffes with longer necks were better adapted to their environment, as they could eat leaves from taller trees.
• Giraffes with longer necks had a higher chance of surviving and reproducing, and passed on the trait of long necks to their offspring.
• Over many generations, this process produced modern giraffes, with very long necks.

Question 11

describe how brown snakes evolve to become green snakes

Answer 11

• there are lots of different colours of snakes controlled by alleles
• being green means they are best suited to grassy / green
  environments, so can be camouflaged
• those that are camouflaged best will be able to catch more food
• those that are camouflaged best will be able to avoid being
  eaten
• survivors’ offspring will inherit the genes / alleles / mutation for
  the shade of green colouration