Natural selection and genetic modification (4) Flashcards
How did Darwin contribute to the theory of natural selection?
He spent 5 years on a voyage and studied plants and animals in different areas of the world. He noticed that members of the same species had different characteristics suited to survive the environment. He also noticed that the characteristics were passed onto offspring.
How did Wallace contribute to the theory of natural selection?
He had the same ideas as Darwin and they published and acknowledged their work. His observations included that some species had warning colours to deter predators.
What is the impact of Darwin and Wallace in modern biology?
Classification - all living organisms descended from a common ancestor so we classify organisms on how closely related they are.
Antibiotic resistance - we understand the importance of finishing the course of drugs to prevent resistant bacteria spreading and we need new antibiotics to fight new resistant bacteria.
Conservation - we understand the importance of genetic diversity and how it helps populations adapt to changing environments.
What is Darwin’s theory of evolution through natural selection?
Individuals in a population show genetic variation because of differences in their alleles. Things like predation, competition and disease act as selection pressures. Individuals with characteristics that make them better adapted to the environment have a better chance of survival and are more likely to breed successfully. The alleles responsible for these characteristics are passed on. The individuals who aren’t as better adapted will die as they are less able to compete leaving beneficial characteristics to be more common.
What evidence is there for human evolution?
Ardi (4.4 million years ago) - ape like big toe to help her climb trees, long arms and short legs and her brain size was the same as a chimpanzee. The structure of her legs suggest she walked upright.
Lucy (3.2 million years ago) - arced feet more adapted to walking, arms and legs were in between the sizes of an ape and a human and her brain was slightly larger than Ardi’s. The structure of her legs suggest she walked upright more efficiently than Ardi.
Leaky (1.6 million years ago) - mixture of human and ape-like features but more human than Ardi. The fossil had shorter arms and longer legs than Ardi making him much more human-like and his brain size was similar to a human’s. The structure of his legs and feet suggest he was better adapted to walking upright than Lucy.
What evidence of human evolution is there based on stone tools?
At first, rocks were hit together to make sharp flakes to scrape meat off bones or crack bones open. Then, rocks were sculpted into simple-hand axes to hunt, dig, chop and scrape meat off of bones. After, there is evidence of flint tools, pointed tools and wooden spears. More recently, arrow heads, fish hooks and needles were made.
How can the tools be dated?
Tools found in deeper rock layers are said to be older as older rock layers are usually below younger ones.
How does the anatomy of the pentadactyl limb provide evidence for evolution?
The pentadactyl limb (limb with five digits) is found in many species but for different uses. The similarity in bone structure provides evidence that species with the pentadactyl limb all evolved from a common ancestor.
How has genetic analysis led to the three domains?
Using RNA sequencing, it was found out that some members of the prokaryote kingdom were not as closely related as once thought. The three domains are:
Archaea - cells with no nucleus but unused sections of DNA.
Bacteria - cells with no nucleus and no unused sections of DNA.
Eukarya - cells with a nucleus and unused sections of DNA.
What is selective breeding?
Selective breeding is the process in which humans artificially select plants or animals to breed together to get favourable characteristics that are useful or attractive.
What impacts does selective breeding have on plants and animals?
It reduces the gene pool in a population. This means that all the organisms are closely related which causes genetic defects and ethical conversations. In addition, if a new disease spreads, there is less chance for resistant alleles being present which could lead to the majority of the population being killed.
Describe the process of tissue culture.
First, you choose a plant you want to clone based on its characteristics. Then, you cut off a several small pieces of tissue from the tips of the roots and shoots. After, you grow the tissue in a growth medium containing nutrients and growth hormones under aseptic conditions. As the tissues produce roots and shoots, they can be moved to compost to carry on growing.
What are the advantages of tissue culture in medical research?
You can study how cells communicate with each other, viruses, cancer cells (how they develop and spread) and how infected cells respond to medicines. Also, cultures of human cells can be developed into tissues.
What is genetic engineering?
A process which involves modifying the genome of an organism to introduce desirable characteristics.
What are the main stages of genetic engineering?
The DNA you want to insert is cut open using a restriction enzyme. The vector DNA is cut open by the same restriction enzyme leaving both with complementary sticky ends. The two DNA strands are joined together by ligase enzymes to make recombinant DNA which is inserted into cells you want.
