B4 Natural Selection and Genetic Modification Flashcards
What happens in natural selection?
- Individuals of a population show genetic variation due to differences in alleles
- Predation, competition and changes in environments mean that the individuals with characteristics better adapted to the selection pressures survive
- These surviving individuals breed, passing on the useful characteristics onto offspring
- These characteristics become more common over time
What did Darwin and Wallace do?
- Darwin came up with the theory of evolution by natural selection when on a 5 year voyage across the world
- Wallace also came up with the theory of evolution by natural selection and they both published their papers together
- ‘On the Origin of Species’ by Darwin was famous and had lots of evidence for evolution
What are the features of Ardi?
- 4.4 million years old
- Long arms and short legs
- Small brain size - similar to a chimpanzee
- Long big toe pointing out to grasp branches
- Walked upright
What are the features of Leakey’s discovery?
- 1.6 million years old
- Short arms and long legs
- Larger brain size - similar size to humans
- Walked upright
What are the features of Lucy?
- 3.2 million years old
- Arms shorter than Ardi
- Slightly larger brain size than Ardi - still similar to chimpanzees
- Walked upright
What groups were in the kingdom classification system?
- Animals
- Plants
- Fungi
- Prokaryotes
- Protists
What were the groups in the three domain classification system?
- Archaea
- Bacteria
- Eukarya
Why do people selectively breed?
- Animals produce more meat or milk
- Crops have disease resistance
- Plants produce bigger fruit
What are the problems with selective breeding?
Reduced gene pool - inbreeding
What is the process for tissue culture?
- Remove a piece of tissue from the parent plant
- Grow the tissue in a growth medium containing nutrients and growth hormones under aseptic conditions to prevent the growth of microbes
What are the medical advantages of tissue culture?
Scientists can look at the effects of a particular substance or environmental change on the cells of a single tissue, without complications from other processes in the whole organism
How is DNA inserted into other organisms?
- Restriction enzymes cut out the DNA you want to insert
- The vector DNA is then cut open with the same restriction enzyme creating complementary sticky ends
- The DNA is joined together by ligase to make recombinant DNA
- The recombinant DNA is then inserted into other cells e.g. bacteria
What are the positives of genetic engineering?
- Crops can be modified to be resistant to pests e.g. Bt toxin
- GMOs can be used to increase crop yields and provide more food for people
What are the negatives of genetic engineering?
- Genetic engineering can have negative effects on the organism e.g. suffering health problems
- The transplanted genes may get out into the environment
What are alternative methods of increasing food production?
- Biological control which can be less harmful
- Fertilisers provide essential nutrients
