topic 4 Flashcards
(34 cards)
what was the ardi fossil
ardipithecus ramidus
1.2 m tall
50kg
skull volume 350
long arms and big toes that stuck out to the side- for climbing trees
structure of leg bones suggests she walked upright
4.4 million years ago
what was the Lucy fossil
Australopithecus afarensis
3.2 million years ago
toes were he same as modern humans- she didnt climb trees
400 skull volume
structure of feet and legs suggests that she walked upright
1.07 m
shorter arms and longer legs
what did leaky discover
discovered a homo erectus 1.6 million years old 1.79 m tall short arms and long legs 850 skull volume structure of legs and feet showed he could walk better than Lucy or ardi.
how have stone tools developed over time
oldest ones are very simple and would be used for skinning animals , scrapping meat from bones
more recent ones are more complex and have more shape- eg fish hooks and spears used to hunt and dig
how can stone tools be dated
carbon 14 dating - date that carbon containing material in tools
rock layer- older rock layer are underneath newer ones- assume that the tool is the same age as the layer of rock
theory of evolution by natural selection
individuals in a population show variation due to difference in their alleles
environmental conditions change- eg competition
by chance some genetic variations make some individuals more adapted to the changes and are more likely to survive
the survivors breed and pass on variation to the offspring
if environmental conditions remain changed, natural selection occurs over and over again and a new species evolves with all individuals having better adapted versions
how antibiotic resistance shows evolution
bacteria develop mutations in their DNA that creates new alleles
Bactria in a population show variation in the amount of resistance to an antibiotic
as the course is started the antibiotic kills the bacteria and the more resistant ones take longer to die
the course is finished early so only the most resistance bacteria survive and reproduce. the offspring inherit the resistance and so the population is now resistant
shows evidence as it makes the bacteria better adapt to an environement where a selection pressure is present and as a result the resistance becomes more present in a population over time
impact of wallace
studied variation between organisms in Indonesia.
he came up with the idea of natural selection independently of Darwin
discovered warning colour used by some species are an example of a beneficial characteristic that has evolved by natural selection
impact of darwin
visited Galapagos islands and noticed there was variation in members of the same species .
read and essay by Thomas Malthus which give him the idea that organisms produced more offspring than could survive and only individuals best suited to the environment pass on their characteristics
received a letter from Wallace that said he had the same idea
Darwin wrote a summary of his ideas which was published along with Wallaces letter in a scientific paper
he then wrote the orgin of species
influence of darwin and Wallace on modern biology
classification- if all organisms descended from a common ancestor then we’re all related in some way- we now classify organisms on how closely related they are
antibiotics- we now understand the importance of finishing antibiotics to prevent resistant bacteria spreading
conservation- we understand the importance of genetic diversity and how it helps populations to adapt to new environments- led to conservation projects
how the pentadactyl limb shows evolution
a limb with 5 digits
in different species the limb has a similar bone structure but a different function
the similarity in structure suggests we have all evolved from a common ancestor and not that the bones were designed for specific purposes independent from each other
Linnaeus classification
divided animals into 5 kingdoms- plants, animals, fungi, prokaryotes, protists( like algae)
he then divided the into smaller groups- phylum, class, order, family, genus, species
named animal using Genus and species- binomial name - species always has a lower case letter
Woese classification
divided animals into 3 domains- archaea (no nucleus, unused DNA)
bacteria (no nucleus, no unused sections) eukaryote (a nucleus, unused sections)
he then divided them into smaller groups- kingdom, phylum, class, order, family, genus, species
how genetic analysis changed classification
showed all organisms apart from prokaryotes have unused sections if DNA
also found that certain archaea genes were more similar to genes of plants and animals then prokaryotes
what is selective breeding
when humans artificially select plants or animals that have certain characteristics and bred more of these organisms making the chosen characteristic more obvious
process of selective breeding
select organisms that have the desired characteristic.
breed them together
select the best of the offspring and breed them together
continue this over future generations and the desired trait will get stronger and stronger and eventually all of the offspring will have the characteristic
what is genetic engineering
a process which involves modifying the genome of an organism to introduce desirable characteristics
produces GMOs
process of tissue culture
choose the plant you want to grow based on its characteristics
put a piece of plant in a bleach solution to sterilise it
sometimes a piece of plant is cut off and put on a sterile nutrient. it is then treated with hormones so it grows roots and shoots
sometimes only a few cells are cut and put on a sterile nutrient to grow into a callus
the callus is treated with hormones so the platelets develop roots and shoots, the platelets are then separated and grown on nutrient medium
when the plants are large enough they are planted into compost
uses of tissue culture in plant breeding
used to produce new plants of a species that is at risk of extinction
produce new individuals of plant species that may be difficult to grow from a seed
used to produce clones of GM plants
uses of tissue culture in medicine
used to see how cells communicate with each other
cell cultures are used to study viruses
can investigate how infected cells respond to new medicines without harm to humans or animals
cultures of humans cells can be developed into tissues
benefits of selective breeding
useful in agriculture- means animals can cope with disease better, have a higher yield, cope with certain environmental conditions, fast growth, better flavour
risks of selective breeding
reduces the gene pool- only certain alleles are selected so alleles that ought be useful in the future are no longer available
no variation so if the environment changes eg a new disease all the animals will be affected because theres less chance of a resistant allele being present
health problems- can be deliberately bred to have negative characteristics for medical research or be bred for characteristics that harm them and may develop health problems eg chicken being bred for more meat.
risks of genetic engineering
seeds for GM plants are expensive
some think GM crops will reproduce with wild plants and pss on their resistant genes that could have unknown consequences
some think eating GM organisms may be bad for health.
ethics- genetically engineered animals may have health consequences later on in life
benefits of genetic engineering
crops be modified to be resistant to herbicides, this means farmers can spray crop to kill weeds without affecting the crop- this increases yield
can engineer bacteria to produce insulin which is better for vegans or religious people
