6 - variation and evolution (END OF TOPIC) Flashcards
what are the 2 causes of different characteristics
- genetic factors - inherited genes from parents through sex cells
- environmental factors - conditions you live in - climate, sunlight etc.
whats a mutation anf its effect
change to the sequence of bases in DNA
lots have no effect on the phenotype but some have a small effect
whats the ‘theory of evolution’
that all of todays living species have evolved from simple life forms that first started to develop over 3 bill years ago
explain darwins idea of survival of the fittest
organisms with the most suitable characteristics for the environment would be more successful competitors and therefore more likely to survive
whats speciation
when over along period of the time the phenotypes change so much that the natural selection forms a completely new species
causes of extinction
- new predators
- new diseases
- can’t compete for food
- catastrophic events (volcanic eruption etc)
what were Lamarcks ideas?
that if an organism used a characteristic a lot in its lifetime then it would change and be passed on - for example - if a rabbit used its legs to run and lot then its offspring would be born with longer legs
features that would be useful to be selectively bred
- make more meat/milk
- disease resistant
- big flowers
main problem with selective breeding
- reduces gene pool - number of different alleles in a population
- this is bc the farmer keeps breeding from the best animals which have very similar desirable characteristics and therefore it is inbreeding
- inbreeding - health problems// if new diseases appear they are all the same so will all die
process of genetic engineering
- useful gene cut from one organism’s genome using an enzyme
- this gets inserted into vector - virus or bacterial plasmid
- then when vector inside new organism the useful gene gets inserted into its cells
examples of genetic engineering
- bacteria GM to produce human insulin to treat diabetes
- GM crops resistant to dieases
- sheep GE to produce drugs in milk
plant cloning through tissue culture - what and advantages to this
- some plant cells put into growth medium with hormones and grow into new clones of the plant
- very fast
- small space
- all year round
plant cloning through cuttings - what an advantages to this
- gardeners take cuttings from good parent plants and replant them - creates clones
- very fast
- very cheap
animal clones with embryo transplamnts
- sperm and egg cell taken from male and female animal
- sperm are then artifically used to fertilise the egg
- embryo developes an then gets split before any cells become specialised
- these embryos then impanted into other animals to give birth to
adult cell cloning - Dolly (famous sheep)
- take unfertilised egg and remove nucleus
- take adult body cell and remove nucleus and put this nucleus into empty egg cell
- stimulate egg cell with electic shock then it will divide by mitosis
- when embryo is a ball of cells its implanted into womb of audult female
- grows into a clone of the origional adult body cell
issues with cloning
- reduces gene pool - less resistant to diseases
- clones might not be as healthy as original
- unsuccessful and kill origional
3 ways fossils can form in rocks
- GRADUAL REPLACEMENT
- teeth, shells, bones (dont decay) get burried, they get replaced by minerals as they decay and form rock like things in origional shape - CASTS AND IMPRESSIONS
- when organism is burried in soft material like clay, later on clay hardens around it leaving a cast of itself - PRESERVATION - NO DECAY
- in amber and tar pits - no oxygen or moisture so no decay
- galciers too cold for decay
- peat bogs too acidic for decay
hypothesises on how life began
- swamp under the sea on earth
- ## organic molecules brought to earth on comets
about fossils
- remains of organisms from thousands of years ago found in rocks
- provde evidence for how mkuch or little organisms have evolved over time
what happens when a species is isolated and separated
- they are separated by a physical barrier - earthquake/floods
- conditions on either side are slightly different
- evolve to have slightly different characteristics better adapted to their specific environment
- eventually after a while they become so different they cant breed together and will be seen as two separate specieis
who was Alfred wallace
his observations contributed hugely to the idea of speciation
how can bacteria become antibiotic resistant
- random mutations that make it resistant
- bacteria reproduce v fast
whats MRSA
superbug that is rly hard to get rid of - resistant to antibiotics
how to prevent antibiotic resistance
- make sure its prescribed by a doctor
- take the full course - (none left)
