Topic 4 - Natural Selection And GM Flashcards
Natural selection
Environment selects which individuals of a species pass on alleles depending on what variation reproduces in the environment
Evidence of evolution to humans
Pentadactyl structure (five fingered limb) shared by many vertebrates
Old classification system
5 kingdoms
5 kingdoms
Plants Animals Fungi Protists Prokaryotes
New classification system
3 domain system
3 domain system
Eubacteria (prokaryote)
Archea (prokaryotes mainly in warm and salty conditions)
Eukaryota (plants, animals, fungi, protista)
Order of human species
Ardi Lucy Homo habilis Homo erectus Homo sapiens
Ardi characteristics
Tree climber
Walked upright
Lucy characteristics
Walked upright
Face ape-like
Homo habilis characteristics
Flat face like humans
Used simple stone tools
Homo erectus characteristics
Long distance walker
Strongly built
Homo sapiens characteristics
Uses complex tools
Selective breeding definition
When plants (maybe animals) are bred together to inherit desired characteristics
What does selective breeding produce
New breeds of animals and varieties of plants
Reasons for selective breeding
Disease resistance Increase yield/size Better to cope with environment Faster growth Flavour
Disadvantages of selective breeding
Less genetic diversity Genetic defects Less desirable characteristics Offspring may not inherit Little genetic variation can result in easy spread of disease
Genetic engineering definition
Changing genome of organism by introducing new genes to create genetically modified organisms
How genetic engineering works
1) Gene cut out of chromosome using enzymes
2) Gene inserted into chromosome in nucleus of different organism
Genome definition
DNA
GM crops
Plants genetically modified so they have new characteristics
What is a vector
Anything that carries gene into a cell eg plasmid
Tissue culture
Using cell cultures to make many identical copies of an organism
Example of how tissue culture is useful
To test drugs on cell cultures to see effects
Why is agar jelly used in tissue culture
Contains nutrients to encourage growth
Advantages of animal cell cultures
- test effect of drugs
- produce important proteins eg antibodies
Advantages of plant cell cultures
- Produce many clones of GM plants
Insulin step 1
Restriction enzymes cut DNA out
Insulin step 2
Unpaired bases left at each end called sticky ends
Insulin step 3
Restriction enzymes cut open plasmid (bacterial DNA) which also have sticky ends
Insulin step 4
Bases with sticky ends mean insulin DNA can be placed in plasmids
Insulin step 5
Enzyme DNA ligase link DNA into plasmid
Insulin step 6
Plasmid places back into bacteria to divide rapidly
What are Bt plants
Contains bacillus thuringiensis which produces a chemical which is poisonous to pest insects (known as Bt toxin)
Example of insect resistant plant
Bt plants
Advantages of GM plants
- Increase crop yield
- Better for biodiversity as less chemicals to kill harmless insects
Disadvantages of Gm crops
- Seed from these plants is more expensive
- insects can become resistant to toxins
- gene may transfer to wild plants through pollination
What solutions are there to providing food for growing populations
Fertilisers and biological control
Advantages of fertilisers
- contain nutrients to encourage growth of cell
- increase crop yield
- good way to use animal waste
Disadvantages of fertilisers
- Can cause eutrophication
- Expensive to make if artificial
- Artificial fertilisers reduce soul biodiversity
What is biological control
When a natural predator, parasite or disease of the pest is used to keep population low
Advantages of biological control
- Pest cannot become resistant
- Control agent can be specific to pest
- Doesn’t leave harmful resedues or kill useful organisms like chemicals
Disadvantages of biological control
- Doesn’t get rid of pest completely
- Control agent may become pest itself
