Natural selection and genetic modification
evolution
Charles Darwin- Darwin was a 19th century English naturalist and studied variation in plants, animals, and fossils Darwin travelled across four continents on a five year voyage one the hms beagle
Darwin's theory of evolution- Darwin's theory of evolution challenged the belief that God created all living things on Earth, which ran counter to popular Christian beliefs at the time. It took him 28 years after his voyage to publish his scientific work and ideas.
steps for natural selection
Individual organisms within a species display a wide range of variation in a particular characteristic.
individuals with characteristics most suited to the environment are more likely to survive and to breed successfully
the characteristics that have enabled these individuals to survive are then passed on to the next generation
evidence for natural selection
Bacteria can evolve quickly due to their rapid reproduction. Bacterial mutations result in new strains. Some bacteria, such as penicillin-resistant bacteria, may develop resistance to antibiotics and become resistant to their destruction. Natural selection can be seen in the evolution of bacteria, which supports Darwin's theory of evolution.
evidence for evolution
Fossil remains have been discovered in rocks dating back millions of years. The oldest rocks contain the fossils of the simplest organisms, while the newest rocks contain the fossils of more complex organisms. This backs up Darwin's theory of evolution, which claims that simple life forms evolved into more complex ones over time.
Fossils provide evidence for the earliest forms of life. Scientists can learn how much (or how little) organisms have changed as life evolved on Earth by studying fossils.
evidence for human evolution
Ardi is a 4.4 million-year-old female human-like fossilised skeleton. Ardi's bones indicate that she could walk upright, but she had very long arms and big toes. Ardi's feet are made up of bones that suggest humans and chimps evolved separately.
Lucy, a female human-like fossilised skeleton from 3.2 million years ago, is also a female human-like fossilised skeleton. Lucy's bones indicate that she walked upright, like a human, but with a small ape-like skull. Lucy's foot bones reveal that she had feet that were similar to modern humans', but with a lot more curved toes.
Despite the fact that their limbs appear to be very different on the outside, many vertebrates have very similar bone structures. The pentadactyl (five-fingered) limb is the name given to this structure. This indicates that many vertebrates descended from a single ancestor.
Crocodiles, birds, whales, horses, bats, and humans all have the same five-fingered bone structure, despite their appearance. This lends credence to Darwin's theory of evolution.
classification system
Kingdoms
phylum
class
order
family
genus
species
genetic modification
genetic modification/ engineering- process of moving a gene(s) from one species to another
what can it be used for
genetically modified crops- genetic modification can be used on crops to make them more resistant to certain types of climates, insects, herbicides or to increase the yield
process of genetic engineering
Restriction enzymes are used to isolate the required gene and leave sticky ends on it. A short section of unpaired bases is known as sticky ends.
The same restriction enzyme cuts a vector, which is usually a bacterial plasmid or a virus, leaving it with sticky ends.
The ligase enzyme connects the vector and the isolated gene.
The gene is inserted into the required cells by the vector.
During early development, the genes are transferred to animal, plant, or microorganism cells, allowing them to develop with the desired characteristics.
questions
Explain how the changes in horse's feet are evidence for evolution. [4 marks]
horses used to live on marshy ground so small horses with bigger feet would because they wouldn't sink, but then the land harden and horses with small feet would survive because they could run quicker