Natural Selection 1- Revision
- Created by: Ammarah123
- Created on: 17-02-18 21:01
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- Natural Selection and Genetic Modification
- Natural Selection and Evidence for Evolution
- Natural Selection- "Survival of the Fittest"
- Bacteria provide Evidence for Evolution
- 1) Bacteria can create new alleles which can change the bacteria's characteristics
- eg. a bacterium could be less affected by a specific antibiotic (a drug designed to kill bacteria or prevent them from reproducing)
- 2) For the bacterium, the ability to resist this antibiotic is a big advantage. In a host who's been treated to get rid of the infection, a resistant bacteria is able to survive than a non- resistant bacterium
- And so it lives longer and reproduces many more times
- 3) Leads to the allele for antibiotic resistance being passed on to lots of different offspring- it's just natural selection
- This is how it spreads and becomes more common in a population of bacteria over time
- 4) Antibiotic resistance provides evidence for evolution because it makes the bacteria better adapted to an environment in which antibiotics are present
- As a result, antibiotic resistance becomes more common in the population over time
- 1) Bacteria can create new alleles which can change the bacteria's characteristics
- Fossils Provide More Evidence for Evolution
- Fossil- Trace of any animal or plant that lived a long time ago. The deeper the rock, the older the fossil
- Provides evidence for evolution as it shows how species have changed and developed over billions of years
- Fossil Evidence for Human Evolution
- 'Ardi'-- Fossil Hominid, 4.4 Million Years Old
- 1) Structure of her feet suggests she climbed trees-- She had an ape-like big toe to grasp branches
- 2) Long arms + short legs (more like an ape than a human) and her brain size was about the same as a chimpanzee's
- 3) Structure of her legs suggests she walked upright like a human.
- The structure of her hand bones also suggests she didn't use her hands to help her walk (like apes do)
- 'Lucy'-- Fossil; Hominid, 3.2 Million Years Old
- 4) Structure of leg bones suggests she waled upright but more efficiently than Ardi
- 1) Had arched feet, more adapted to walking than climbing and no ape- like toe
- 2) Size of legs and arms was between what you would expect to find in apes and humans
- 3) Brain was slightly larger than Ardi's but still similar in size to a chimp's brain
- Leakey and His Team found Fossil Hominids 1.6 Million Years Ago
- 2) Short arm + legs are much more human than ape and his brain size was much larger than Lucy's-- similar to human brain size
- 1) One of their finds was Turkana Boy-- 1.6 million year old fossil
- He had a mixture of human and ape features but was more human- like than Lucy
- 3) Structure of legs + feet suggests he was even better adapted to walking upright than Lucy
- 'Ardi'-- Fossil Hominid, 4.4 Million Years Old
- Natural Selection and Evidence for Evolution
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