How is selective breeding carried out?
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How is selective breeding carried out?
The selective breeding process involves:
the selection of individuals with characteristics that are desired by humans
crossing together individuals with desired characteristics
selection of offspring with desired characteristics and crossing them together
repetition of the process over many generations
What is the purpose of selective breeding?
The purpose of selective breeding is to improve the yield from crops and domesticated animals.
What are some features that might be selectively bred for in plants?
Features that might be selectively bred for in plants include:
increased yield
disease resistance
pest resistance
frost resistance
What are some features that might be selectively bred for in animals?
Features that might be selectively bred for in animals include:
faster growth
disease resistance
gentle temperament
increased milk yield
Define the term tissue culture.
Tissue culture is the process of growing cells or tissues in a nutrient medium.
What is the purpose of nutrient agar in tissue culture?
Nutrient agar provides a growth medium for cells to grow and divide, facilitating the tissue culture process.
What is a callus in tissue culture?
A callus is a mass of unspecialised cells that develops on the nutrient medium from the initial tissue sample.
True or False?
The equipment used for tissue culture must be sterilised before use.
True.
All of the components must be sterilised prior to tissue culture to ensure that the correct cells grow, and to avoid infection.
Why might the cells of a callus be treated, e.g. with plant hormones, during the tissue culture process?
The cells of a callus might be treated to encourage them to differentiate into particular cell types. E.g. the cells in a plant callus might be treated to encourage them to develop into roots or shoots.
How can tissue culture technology be used in plant breeding?
Tissue culture can be used in plant breeding as follows:
to produce many clones of a plant variety with desirable characteristics quickly and cheaply
to reduce the risk of spreading disease from imported plant varieties
to propagate rare species that are difficult to grow from seed
How can tissue culture technology be used in medical research?
Tissue culture can be used in medical research as follows:
studying the development of viruses which need host cells to reproduce
looking at cell-to-cell communication, e.g. the effects of insulin on cells
studying the effects of new drugs on tissues without risking harm to an individual organism
growing new human tissues for transplant
What is genetic engineering?
Genetic engineering is a process by which the genome of an organism is altered to provide it with desirable characteristics.
What are some examples of desirable characteristics that could be introduced by genetic engineering?
Desirable characteristics that can be introduced by genetic engineering include:
the ability to produce specific proteins, e.g. human insulin
improved pest / disease / weather / herbicide resistance in crops
improved nutritional content of foods, e.g. golden rice
What is the role of restriction enzymes in genetic modification? (Higher Tier Only)
Restriction enzymes are used in genetic modification to cut DNA at specific locations, allowing for the isolation of genes and the insertion of genes into vector DNA.
True or False?
During genetic engineering the desired gene is isolated using the same restriction enzyme that is used to cut the vector DNA. (Higher Tier Only)
True.
During genetic engineering the desired gene is isolated using the same restriction enzyme that is used to cut the vector DNA. This is because:
DNA that is cut by restriction enzymes has sticky ends
DNA cut with the same restriction enzyme will have complementary sticky ends that can bond together
How does DNA ligase contribute to genetic modification? (Higher Tier Only)
DNA ligase in genetic modification forms the bonds between adjacent DNA fragments. This joins DNA fragments together to form a continuous DNA strand.
Define the term vector in genetic modification. (Higher Tier Only)
Vectors are mechanisms by which DNA is transferred into new cells, e.g. plasmid vectors.
What is the role of plasmids in genetic modification? (Higher Tier Only)
Plasmids in genetic engineering are a form of vector, allowing DNA to be transferred into bacterial cells.
How have crops been genetically modified with genes from Bacillus thuringiensis?
Crops been genetically modified to contain genes from Bacillus thuringiensis that code for production of a toxin known as Bt toxin.
What is the advantage gained from growing Bt crops?
The advantage gained from growing Bt crops is that the crops produce Bt toxin; this toxin kills insect pests that eat any part of the plant, so reducing pest damage and increasing yield.
What are the advantages and disadvantages of growing pest resistant crops?
Advantages and disadvantages of growing pest resistant crops include:
Advantages | Disadvantages |
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What is biological control in agriculture?
Biological control is the use of living organisms to control pests and weeds, so increasing crop yield.
What are the advantages and disadvantages of using biological control in agriculture?
Advantages and disadvantages of using biological control in agriculture include:
Advantages | Disadvantages |
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True or False?
Fertilisers are used to prevent the growth of unwanted weeds in crop fields.
False.
Fertilisers are used to provide the soil minerals that crop plants need to grow, e.g. nitrates and magnesium ions.
Unwanted weed growth is prevented by the use of herbicides, also known as weedkillers.
What are the advantages and disadvantages of fertiliser use in agriculture?
Advantages and disadvantages of fertiliser use in agriculture include:
Advantages | Disadvantages |
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True or False?
Concerns about the health effects of consuming GM crops have been fully explored.
False.
Some feel that the health effects of consuming GM crops over long time periods have not been thoroughly investigated.
What are the potential benefits of genetic engineering in agriculture and medicine?
Potential benefits of genetic engineering in agriculture and in medicine include:
GM crops generally show increased yields
improved food security
reduced use of chemicals such as pesticides and herbicides
production of useful substances, such as human insulin to treat diabetes
treatments for some inherited disorders
What are the potential risks of genetic engineering in agriculture and medicine?
Potential risks of genetic engineering in agriculture and medicine include:
concerns around the effects of GM on non-target plant and animal species
herbicide-resistant GM crops increase dependency on one type of herbicide
organisms can develop resistance to the effects of GM crops
new genes may escape into wild plant populations
genetic modification in medicine needs to be carefully regulated, e.g. to prevent unethical genetic modification of humans
True or False?
Selective breeding cannot be used to introduce disease resistance into a population.
False.
Some individuals may develop disease resistance as the result of mutation, so selective breeding from these individuals over time can result in disease resistant populations.
How can selective breeding cause harm?
Problems that can be caused by selective breeding include:
humans may choose traits that are harmful to animals, such as flat faces in dogs
selective breeding can result in problems from inbreeding if not carried out carefully
selective breeding reduces genetic variation, so can reduce the ability of a population to respond to change
What was the Human Genome Project?
The Human Genome Project was the international research project that sequenced the entire human genome.
What are some possible medical applications of the data from the human genome project?
Possible medical applications of the data from the Human Genome Project are:
linking the presence of certain gene variants with disease risk
the ability to test for the presence of alleles that cause disease
developing new and improved medical treatments that target genes
choosing medical treatments on the basis of an individual's alleles