Biology Topic 4 Natural Seletion and Genetic Modification Flashcards
Def Genetic Variation
When the characteristics of individuals varies due to differences in genes
Def Environment Change
When lack of resources (less food) leads to more competition between organisms
Def Natural Selection
By chance variations make some individuals better at coping in the environment (survival of the fittest) and survive better than others
Def Inheritance
They survive better and pass on better adapted variations to offspring so more individual have it
Def Evolution
If environmental change remains, natural selection occurs over and over again and new species evolve
How to work out the age of stone tools
Scientist can work out the age by looking at the amount of radiation in the rock layer above and below it
How stone tools relate to skull volume
Older tools = more simple
Newer tool = more sophisticated
The increasing complexity of tools suggests that humans evolved to become more intelligent
Also the skull volume of humans increases as they evolved
Def Common Ancestors
If two animals have evolved from the same species they have a common ancestor
Antibiotic resistant bacteria
Ending the antibiotic early causes the high resistant bacteria to survive and reproduce. Now the bacteria will be resistant and the antibiotic won’t work
Rats resistant to warfarin
At first most rats died. Then after 10 years most rats were resistant. Due to genetic variation some rats were resistant. Warfarin killed the non resistant rats the the resistant ones survive and reproduce
Def Artificial Selection
When humans choose certain organisms that have useful characteristics
Def Selective Breeding
Breeding organisms with useful characteristics over and over again. This makes an new species with the useful characteristics
Reasons for selective breeding
- disease resistant
- yield
- coping with certain environmental conditions
- faster growth
- flavour
Def Genetic Engineering
Changing DNA often by inserting genes from another organism. Creates GMO with useful characteristics. Faster than artificial selection but more expensive
Selective breeding risks
- only certain alleles are selected so others become rare or disappear. They could be useful in the future but aren’t available
- All organisms are similar so a change in condition would affect all organisms
- Animal welfare e.g. chicken with so much breast meat they can’t stand
Genetic Engineering issues
- Expensive
- Gm crops may reproduce with wild plants and their offsprings genes may have unknown consequences
- People thing it is harmful to eat
How pentadactyl limb shows evolution
The fact that most vertebrates have limbs with five fingers shows that evolution has a occurred from a common ancestor
Process of tissues culture
- Cut tissue sample from parent plant
- Prepare agar jelly containing sugars,nutrients and growth hormones
- Place sample in agar jelly
- Store in warm place with light to encourage cell division, growth and differentiation
Advantages of tissue culture in plant breeding
- Produces many identical plants from just one parent
- can be grown to make plant products
- produce disease free plants
Stages of genetic engineering
- DNA from human cell is cut by restriction enzymes
- They make staggered cuts leaving unpaired bases at each end, called sticky ends
- Bacteria contains plasmids. The same restriction enzyme is used to cut the plasmid leaving sticky ends with matching bases
- Pieces of DNA containing insulin are mixed with the plasmids. Ligase enzyme is added to link the DNA back together
- The plasmids are inserted into bacteria and it is grown in fermenters
Def Vectors
Vector is a thing that carries the new gene into a cell. In the case of insulin the vector is plasmid
Creating Bt plants
- The bacteria Bt naturally produces a chemical that is poisonous to insect pests
- The gene for Bt toxin can be cut out and inserted in the DNA of a plant cell
- When an insect tries to eat them, the poison kills them
Advantages of Bt plants
- Crop damage is reduced so crop yield should increase
* Less chemical insecticides are used so other harmless insects are less likely to be harmed (better for biodiversity )
Disadvantages of Bt plants
•Seed for plants are more expensive
•Insects may become resistant to Bt
•Bt gene could transfer by pollination, which could make those plants resistant to pests too
Meaning predators have less food
What is done to meet population food demand
Agricultural solutions include using fertilisers and biological control
Advantages of fertilisers
- Contain nutrients (nitrogen, phosphorus, potassium) that help crops grow
- Increase crop yield = more food
- Good way to use animal waste
Disadvantages of fertilisers
- Excess fertilisers can cause eutrophication
- Artificial fertilisers are expensive to make
- Can reduce soil biodiversity
- It can flow into streams and lakes affecting humans and animals if they drink the water
Def Biological Control
Using natural predators, parasite or disease of the pest to keep the pest population low
Advantages of biological control
- Pest can not become resistant
- The control agent is specific to pest so won’t kill useful animals
- Avoids chemical pesticides which can leave harmful residue
Disadvantages of biological control
- Doesn’t get rid of pests complete
- The control agent may become the pest
- When pests die the predators have less food
Advantages of tissue culture in medical research
- Can be developed into tissue that can be made into artificial body parts such as the trachea and bladder
- Cancer cells can be studied to see how it spreads and develops
- scientists can investigate how infected cells respond to new medicine without risking harm to animals
Ardi and Lucy
Ardi had long arms and big toes to climb trees, she would have walked upright
Lucy’s toes were more like humans but more curved. She also walked upright
Strains of Bt toxin
There are different strains of Bt toxin so that new versions of the GM crop can be made if pests become resistant
How are organisms classified
5 Kingdoms based on how they look like, animals, plants, fungi, protists, prokaryotes
Can be divided in 3 Domains
Archaea no nucleus, unused sections of DNA
Bacteria no nucleus, no unused sections
Eukarya a nucleus, unused sections
