B4- Natural Selection and Genetic Modification Flashcards
Selection pressures that could affect an individual’s chance of survival
- predation
- competition for resources (e.g. food, water, mates, etc.)
- disease
MRSA is a bacterium that is resistant to antibiotics, what does this mean?
The bacteria cannot be killed by antibiotics
Why can bacteria evolve so rapidly?
-they reproduce at a fast rate
What is meant by ‘natural selection’?
Individuals with characteristics that make them better adapted to the selection pressures in their environment have a better chance of surviving and reproducing successfully. This means that the alleles that are responsible for the useful characteristics are more likely to be passed on to the next generation.
How can a population of bacteria become resistant to a particular antibiotic
Bacteria can develop random mutations in their DNA that make them resistant to a particular antibiotic. Antibiotic-resistant bacteria are more likely to survive and reproduce, passing on the gene for resistance. The gene for resistance becomes more common in the population due to natural selection.
What was Darwin’s book called?
On the origin of the species
When was Darwin’s book published?
1859
How have Darwin and Wallace’s ideas about evolution influenced how living organisms are classified by biologists today?
- led to the understanding that all living things have descended from a common ancestor and must therefore be related in some way
- based on this, biologists now classify organisms based on how closely related they are
Other than changing how organisms are classified, how have Darwin and Wallace’s ideas had an impact modern biology?
- now understand the importance of finishing a course of antibiotics to prevent resistant bacteria spreading and the need to constantly develop new antibiotics to fight newly evolved bacteria
- now understand the importance of genetic diversity and how it helps populations adapt to changing environments which has lead to conservation projects to protect species
Wallace observed that some butterfly species have warning colours that are used to deter predators from eating them. How does this observation provide evidence to support the theory of evolution by natural selection?
-warning colours are an example of a characteristic that can make an individual more likely to survive and breed successfully
How many digits does a pentadactyl limb have?
-five
What does a complexity of a stone tool say about its age?
The simpler the tool the older it’s likely to be
How can stratigraphy (the study of rock layers) be used to date stone tools?
The deeper the layer of rock that a stone tool is found in, the older the tool is likely to be. This is because older rock layers are normally found below younger layers.
Why do differences between stone tools used by each Homo species provide evidence for evolution?
-the stone tools become gradually more complex over time, suggesting that their brains were getting larger, providing evidence for evolution.
The pentadactyl limb of a whale and a bird have very different functions, but have similarities in their structures. Explain why this provides evidence that a whale and a bird share a common ancestor.
It is very unlikely that a whale and a bird would have limbs with similar structures unless they both evolved from a common ancestor that also had a pentadactyl limb.
What does classification mean?
Organisation of living organisms into groups
Name the five kingdoms traditionally used in classification
animals, plants, fungi, prokaryotes, and protists
Name the three domains proposed for use in classification instead of the five kingdoms
archaea, bacteria, and eukarya
How can the genes of an organism be used to determine how closely related it is to other organisms?
The sequence of DNA bases in the genes can be determined and then compared with other other organisms. Those with more similar DNA sequences are more closely relaete
What is ‘inbreeding’?
When closely related organisms are bred together
Two characteristics a cattle farmer might want to develop in her cows over time using selective breeding.
- increase the size of the cattle so they produce more meat
- increase the amount of milk produced by the cows
When carrying out a tissue culture of animal cells how are the cells in a sample separated from each other before they are placed in the culture vessel?
Using enzymes
How can tissue culture be used in medicine?
-to carry out experiments on tissues in isolation, so the effects of a particular substance or environmental change on the cells of a single tissue can be tested
How could a farmer clone an apple tree?
The farmer could put small pieces of tissue from the apple tree in a growth medium containing nutrients and growth hormones. This should be done under aseptic conditions. Once the tissues have started growing shoots and roots, the farmer can move them to potting compost to carry on growing.
Why might a farmer want to clone an apple tree with unusually colourful and attractive fruit?
So he can produce genetically identical copies of the apple tree that all produce unusually colourful and attractive fruit.
What is ‘genetic engineering’?
-involves modifying an organism’s genome to introduce desirable characteristics
Give one useful substance that bacteria have been genetically modified to produce?
Insulin- used to treat diabetes
How can genetically engineered animals be used in medicine?
- human genes that produce useful proteins can be transferred into animals such as sheep or cows
- these proteins can then be extracted from the animal’s mild and used to treat patients
- animals that have organs suitable for organ transplantation into humans might also be produced in the future
One ethical concern with genetically modified animals being used in medicine.
-many genetically modified embryos don’t survive and some genetically modified animals suffer from health problems later in life
Many GM crops contain transplanted genes that make them resistant to weed killer. Why could this be a problem if these genes got out into the environment?
Transplanted genes could be picked up by a weed. This would make the weed resistant to weed killer, which would be a big problem for farmers if the weed spreads.
How can the use of fertilisers improve crop yield?
-can increase crop yield when growing crops on poor soil by providing the minerals the crops need for growth.
Two ways in which GM crops can improve people’s health?
- increase food production, so more people would have enough food to eat
- can also be engineered to contain more nutrients so people are less likely to suffer from deficiency diseases
An advantage of using biological control instead of chemical pesticides
Biological control can have longer-lasting effects on the pest population than chemical pesticides and can be less harmful to wildlife
Explain how transplanting genes form ‘Bacillus thuringiensis’ inti crops has increase crop yield
- crops containing genes from Bacillus thuringiensis produce toxins that make them resistant to insect pests
- this means less of the crop is eaten by pests, increasing crop yield
Why are people concerned that the genes from Bacillus thuringiensis will be less beneficial in the future?
The insects that feed on the crops are constantly exposed to the toxin, so it’s possible that the insects will develop resistance to the toxin and be able to eat the crop.
