4 - Natural Selection and Genetic Modification Flashcards
What is extinction?
Extinction is when there are no remaining individuals of a species still alive
How long ago did simple life forms first develop?
Over three billion years ago
Give two sources of evidence for evolution.
Fossils and antibiotic resistant bacteria
What is meant by natural selection?
Organisms with the most suitable characteristics for the environment are more likely to survive and reproduce, so they are more likely to pass on the genes for their characteristics to the next generation
Describe possible reasons why a species might become extinct when a new species is introduced to the same habitat.
E.g. individuals of the original species could be eaten by the new species, or they might not be able to compete with the new species for food. The new species might also introduce a new disease to the habitat that the original species can’t survive. Each of these would lead to a reduction in population size and, potentially, extinction
How could you know for certain whether two populations of a species had become two new species after the phenotype of each population changed over time?
If they had formed two new species, they would no longer be able to interbreed to produce fertile offspring
Suggest two characteristics that a cattle farmer might want to develop in his cows over time using selective breeding
They might want to increase the size of the cattle, so that they produce more meat, and to increase the amount of milk produced by the cows.
What is inbreeding?
Inbreeding is when closely related organisms are bred together
At a plant nursery, a species of flowering plant is grown to be sold for decorative purposes. There is some variation in the sizes of the flowers produced by this plant. The nursery wants to grow plants with particularly large flowers, as they are more popular. Describe how this could be achieved.
Select the individuals that produce the largest flowers. Breed these together. Then select the individuals of the offspring that produce the largest flowers and breed these together. Continue doing this with each new generation until the trait gets stronger. Eventually all of the plants will produce large flowers
A farmer has used selective breeding to increase the yield from his tomato plants. A new disease gets into the greenhouse. The first plant to be infected dies. Suggest what might happen next and why.
The other tomato plants in the greenhouse are also likely to die from the disease. This is because selective breeding results in populations of closely related organisms with little genetic variation. Therefore, if one plant has died from this disease, it is unlikely that there will be alleles for resistance to the disease in the other tomato plants in the greenhouse
Give one useful substance that bacteria have been genetically modified to produce
e.g insulin
This could be used to treat diabetes
Genetic modification is being explored in medical research. How could genetic modification be used in medicine in the future?
It could be used to treat inherited diseases caused by faulty genes
Give two reasons why crops may be genetically modified
e.g to increase crop yields or to make them resistant to disease, insects and herbicides.
A population of a species of insect lives in a crop field. Explain one possible effect that growing GM crops in this crop field may have on the population of these insects.
Growing GM crops may affect the number of wild flowers that live in and around the crops. This could reduce the insect population because it may be removing their food source
How do scientists transfer an isolated gene into a target cell?
The isolated gene is inserted into a vector, usually a bacterial plasmid or a virus, and the vector is inserted into the target organism’s cells
