What was Lamarck’s idea on evolution? ( 2 marks)
Jean-Baptiste Lamarck suggested a theory called ‘the inheritance of acquired characteristics’. His theory stated that characteristics which develop during an organism’s lifetime can be passed on to the next generation.
Explain how evolution occurs through natural selection? (4 marks)
Organisms within species may show variation because mutation(s) occur in individuals. This results in the individuals with characteristics most suited to the environment being more likely to survive, reproduce/breed and pass on their genes to their offspring in the next generation.
Explain why Darwin’s theory of evolution was not accepted at first.(2 marks)
- The theory undermined the idea that God made all the animals and plants that live on Earth. - There was insufficient evidence at the time. - The mechanism of inheritance / variation was not yet known at the time.
What does the theory of evolution state? (2 marks)
Present day organisms have evolved from simpler organisms over long periods of time or millions / billions of years
The dodo lived on a small island in the middle of the Indian Ocean. Its ancestors were pigeon-like birds which flew to the island millions of years ago. There were no predators on the island. There was a lot of fruit on the ground. This fruit became the main diet of the birds. Gradually, the birds became much heavier, lost their ability to fly and evolved into the dodo. Suggest an explanation for the evolution of the pigeon-like ancestor into the flightless dodo. (4 marks)
- mutation / variation - produces smaller wings / fatter body - wings no longer an advantage since no predators - wings no longer an advantage since food on ground - fatter body can store more energy when fruit scarce - successful birds breed / pass on genes
Flamingos feed on organisms that live in mud at the bottom of lakes. Leopards prey on flamingos. Flamingos find it difficult to fly if their feathers get wet. Flamingos have evolved very long legs. How would each of the following theories explain the evolution of these long legs? (a) Using Darwin’s theory (3 marks)
- Variation / range of leg sizes / due to mutation - ones with longer legs could feed n deeper water / get more food or - long legged ones less likely to get feathers wet or - long-legged ones could escape from leopards Those with the selective advantage survive / breed / pass on genes
Flamingos feed on organisms that live in mud at the bottom of lakes. Leopards prey on flamingos. Flamingos find it difficult to fly if their feathers get wet. Flamingos have evolved very long legs. How would each of the following theories explain the evolution of these long legs? b)Using Lamark’s theory (2 marks)
- Flamingos stretched their legs as they had an inner need(to be able to feed in deeper water/ keep feathers dry / escape from leopards) - Longer legs / acquired characteristic inherited by offspring
What is meant by natural selection? (2 marks)
- survival of fittest - amplification of fittest ie has adaptations to survive (selective advatange) - go on to breed or genes / characteristics passed on to next generation
What is this?
An evolutionary tree
