topic 4 - natural selection and genetic modification Flashcards
how bacteria become resistant
new strain of bacteria happens to mutation
varying resistance to bacteria due to mutations (selection pressure is usually antibiotics)
due to antibiotics, less resistant bacteria die
more resistant bacteria survive
become more common and reproduce
resistant gene is passed on
natural selection model answer
variation for (insert trait) because of sexual reproduction and mutations
there is a selection pressure (availability of food/mates/habitats)
the best adapted (insert species) outcompete the others
they survive and reproduce passing on their advantageous gene of (insert gene)
this is survival of the fittest
over generations, (insert trait) changes
who’s ardi
a fossil who is 4.4 million years old
structure of feet suggested she climbed trees
ape like big toe
brain size same as chimpanzees
structure of her legs suggests she walked upright
her hand bone suggests she didn’t use her hands to help her walk like apes do
who’s lucy
3.2 million years ago
arched feet
arms and legs size was in between size of apes and humans
brain slightly larger than ardi’s but still similar to chimp
leg bones suggest she walked upright and more efficiently
who’s leakey
1.6 million years ago
more human like than lucy
big brain like human
better adapted to walking upright
2.5-1.5 million years ago tools
simple stone tools they hit rocks together to make them sharp
2-0.3 million years ago tools
sculpted rocks into shapes to produce more complex tools like simple hand axes
300 000-25 000 years ago tools
more complex tools - flint tools and wooden spears, pointed tools
200 000 years ago - present tools
flint tools widely used, arrowheads, fish hooks
why are dating tools and fossils not accurate
rock layers can move over time
what’s a pentadactyl limb
limbs with five digits
what does pentadactyl limb suggest
species with it all evolved from a common ancestor that had it
what are the 5 kingdoms
animals
plants
fungi
prokaryotes - all single celled organisms without a nucleus
protists - eukaryotic (with a nucleus) single celled organisms
why is five kingdom classification bad
out of date
using RNA sequencing, we found out that some members of prokaryote kingdom are not as closely related as first thought
three domain system
archaea - look similar to bacteria but DNA and RNA sequences say they’re different. found in hot springs and salt lakes
bacteria - true bacteria e.g. E Coli
eukarya- broad range of organisms including fungi animals plants and protists
selective breeding model answer
from existing stock, select ones with desired characteristics
breed them together
select best of the offspring and breed them together
continue over several generations
until desirable trait gets stronger and stronger
eventually all offspring will have desired characteristic
how is selective breeding useful in agriculture
increases yield
disadvantages of selective breeding
reduces gene pool - inbreeding
health problems - genetic defects e.g pugs breathing problems
new disease appears and due to less variation, less chance of resistant alleles
benefits of cloned plants
all tasty fruit
pesticide resistance
how to grow plants using tissue culture
tissue remove from tip of parent plant
tissue placed on a medium containing growth hormones
tissues produce shoots and roots
advaantages of animal tissue in medicine
experiment on tissues in isolation
look at effect of particular substance on single tissue
how animal tissue culture is carried out
extract tissue cells from animal
separate cells using enzymes
put them in a growth medium with nutrients to grow and multiply
after lots of cell division, cells can be split up again and placed into separate vessels to encourage more growth
stored for future use
why are genetically modified crops good
increase food production - overpopulation
resistant to pests and can grow in drought conditions
combat deficiency diseases e.g. golden rice gives more vitamin A
why are genetically modified crops bad
people can’t afford to buy food. lack of it isn’t an issue
fears that countries may become dependent on people who sell GM crops
poor soil can be an issue so even GM crops wont survive
