B14 Flashcards
What is variation?
Differences in the characteristics of individuals in a population
What are the two causes of variation within a species?
Genetics
Enviroment
What is evolution?
Gradual change in the inherited traits within a population over time
Outline the thoery of natural selection?
1) genetic variation exists due to mutations
2) random mutation gives an organism a selective advantage
3) organism is better adapated to the enviroment
4) organism reproduces passing alleles onto the next generation
How do two populations become different species?
When their phenotypes become different to the extent that they can no longer interbreed to produce fertile offspring
What is selective breeding?
Process by which humans select organisms with desirbale charcateristics and breed them to produce offspring with simalir phenotypes
Outline the main steps involved in selective vreeding
1) identify a desired characteristic
2) select parentd that show the desired traits and breed them
3) select offspring with the desired traits and breed them
4) process repeated until all offspring have the desired traits
What is the mainadvantage of selective breeding?
Crops produce a higher yield of grain
Plants produce larger fruit
Animals with gentle nature.
Outline the disadvantages of selective breeding?
Reduces the gene pool
Inbreeding resultd in genetic disorders
More likely to get harmful recessive alleles
What is genetic engineering?
The modification of the genome of an organism by the insertion of a desired gene from another organism
Examples of uses for GM plants?
Disease resistance
Produce larger fruits
What is a use for genetically modified bacteria cells?
To produce human insulin to treat diabetes
Describe the benefits of genetic engineering?
Increases crop yields
Useful in medicine
GM crops produce scarce resources
Describe the risks of genetic engineering?
Negative environmental impacts
GM seeds are exspensive
What are benefits of bt crops?
Increased crop yields
Bt toxin is specific to certain insects so is not harmful to other organisms
Describe the process of genetic engineering?
1) DNA is cut at specific base sequences
2) enzymes are used to isolate the required gene, this gene is inserted into a vector(usually a bacterial plasmid or virus)
3) genes are transferred to the microorganisms Cells, they develop with the desired characteristics
What is a vector?
Structure that delivers the desired gene into the recipient cells
How can plants be cloned?
Taking plant culture
Tissue culture
Describe how plants are grown using tissue culture?
1) select a plant that shows desired characteristics
2) cut multiple sample pieces from the meristem tissue
3) grow in a Petri dish containing growth medium
What must be ensured when preparing tissue culture?
Ensure aseptic conditions to prevent contamination of organisms
What does the growth hormone cobtain?
Nutrients and growth hormones
What are the advantages of growing plants by tissue culture?
Fast and simple process
Requires little space
Enables the growth of many plant clones
Useful in preserving endangered plant species
What are the disadvantages of growing plants by tissue culture?
Reduction in the gene pool
Plant clones have a low survival rate/life expectancy
Could increase the prescribe of harmful recessive alleles
Detail the process of the plant cuttings method of plant cloning?
1) branch is cut off the parent plant
2) stem is planted
3) plant hormones are used to encourage new root development
4) plastic bag is used to cover the plant to keep it warm and moist
5) new roots and plants is formed
