Topic 4 - Natural Selection and Genetic Modification Flashcards
evolution
gradual change in the characteristics of a species over time
natural selection
by chance the variations of some individuals make them better at coping with the change than others (survival of the fittest)
what’s a piece of evidence that shows human evolution
- fossils
- stone tools
how can you tell how old a stone tool is
the older stone tools would be more simple (more worn down) and the more recent stones would be more sophisticated
genetic variation
the characteristics of individuals vary due to differences in genes
environmental change
conditions in an area change
e.g. lack of food causes more competition between organisms
inheritance
the survivors breed and pass on their variations to their offspring
common ancestor
when one species is the ancestor of two or more species
three reasons why the theory of evolution by means of natural selection was slow to be accepted
- lack of supporting evidence
- limited scientific understanding of genetics and inheritance
- conflicting religious beliefs (challenge in correction stories from bible)
what two scientists helped with developing the theory of evolution
Charles Darwin and Alfred Wallace
antibiotic resistance
happens when germs like bacteria and fungi develop the ability to defeat the drugs designed to kill them
what causes antibiotic resistance
when you take antibiotics the least resistant bacteria is killed however some bacteria (the more resistant) survives and start to spread making more bacteria resistant
how did the rats become resistant to warfarin
- due to genetic variation caused by mutations, there were some rats in the population that survived the poison - the majority of the rats would’ve died
- these resistant individuals were able to survive
- they then bred with other survivors and had offspring with similar features
- this process occurred over many generations until the only individuals and the population were the warfarin resistant individuals
why did the warfarin not cause the rats to become resistant
- because the warfarin provided the environment for natural selection to occur within
- only the rats with beneficial random mutations are able to survive when they eat the poison
pentadactyl limb
vertebrates have limbs with 5 fingers
pentadactyl limb theory
the limb similarity suggest evolution from a common ancestor
classification system
dividing organisms into groups based on what they look like
name the kingdoms of classification
animals, plants, fungi, protists, prokaryotes
what happens in selective breeding
- you select individuals with desirable characteristics
- these individuals are bred together
- they produce offspring with the desirable characteristic
genetic engineering
when you change the DNA of an organism (its genome) by inserting genes from another; this creates genetically modified organisms (GMOs)
process of genetic modification in bacteria
- cut out desirable gene using restriction endonuclease enzyme
- cut out a bit of the plasmid with the same restriction endonuclease enzyme
- this cutting leave strands of DNA with jaggered ends called sticky ends
- the desirable gene is joined in with the plasmid using an enzyme called ligase; this is recombined DNA
- the plasmid is returned to the bacterial cell
stem cells
special cells produced by bone marrow
tissue culture
is a technique in which tissues of plants or animals are cultured and grown in a laboratory
why must everything be sterilised during tissue culture
to prevent the growth of microorganisms (e.g. bacteria)
what does it mean if something is sterilized
to make something completely clean and free from bacteria
callus
a clump of undifferentiated plant cells
name things that plants and animals are often selectively bred for:
- disease resistance (how are they cope with diseases)
- increase yield (how much useful product they make)
- coping with certain environmental conditions
- fast growth
- make new products
- flavour
cell culture
a collection of techniques and resources in which cells that were part of an organism are growth in an artificial controlled environment
ways that cell culturing be useful:
- has many uses in medicine - culturing a thin layer of cells on a solid medium makes it easier to study how cells communicate with each other
- needed to study viruses
- cultures of cancer cells have been developed to study how cancer develops and spreads
- investigate how infected cells respond to new medicines without risking harm to animals or humans
pesticide
a substance used for destroying insects or other organisms harmful to plants or animals
insecticide
a type of pesticide used to kill insects
fungicide
a type of pesticide that kills or prevents the growth of fungi and their spores
fertilizer
natural or artificial substance containing the chemical elements that improve growth and productiveness of plants
weed
a plant that’s considered undesirable in a particular situation
biological control
the use by humans of beneficial insects, like predators or pathogens such as fungi and viruses to control unwanted insects, weeds or diseases
artificial fertiliser
man-made fertiliser
herbicide
a substance that is toxic to plants, used to destroy unwanted weeds
organic farming
no use of artificial fertilisers, no pesticide and no medicine (all natural)
disadvantages of using genetic modification
- harm to human or animal health
- cross-contamination
disadvantages of selective breeding
lack of genetic diversity in alleles a crop - future crop scientists have less alleles to develop varieties in the future
process of genetic engineering
- cut out a desirable gene using restriction endonuclease enzyme with a desirable characteristic from one organism -> the gene now has ‘sticky ends’ (unpaired bases)
- transfer the gene to a different organism
- the other organism now has the desirable characteristic - use the enzyme ligase to stick them together
- this produces a genetically modified organism (GMO)
genetic engineering
modifying an organisms genome
Genetic engineering issues
- if GM cross reproduce with wild plant varieties and pass on their resistant genes, these genes may have unknown consequences in wild plants
- People think that eating GM organisms may be bad for health
How to genetically engineer bacteria
- scientist use restriction enzymes to cut useful gene of an organism DNA
- This cutting these strands of DNA with jagged end with ‘sticky ends’ (unpaired bases at each end)
- The new section of DNA is inserted into the plasmid
- if the two sticky ends match, they can be joined together using an enzyme called ligase
advantages of making insulin using genetically modified bacteria rather than extracting it from animals
- Cheaper
- suitable for vegans or people who do not eat pork or beef for religious reasons
what is BT toxin?
Natural insecticide protein
Explain why using an insect resistant variety of genetically modified plants might be better for the environment than spraying non genetically modified plants with insecticide
Because it only affects insects that bite into the plant tissues so insect predators such as ladybird and spiders aren’t harmed
—> less animals are killed innocently
how does adding fertiliser affect the yield of crop plants?
Help increase the yield of crop plants because it contains mineral ions that plants absorb from the soil to make healthy new cells
explain the theory of evolution by natural selection
- there is variation within the species due to genetic mutations which make some organisms have certain characteristics that make them more likely to survive than others
- therefore there is a struggle for existence so adapted organisms survive and unadapted organisms die (‘survival of the fittest’)
- this leads to the offspring inheriting the characteristics needed to survive
- this is repeated over generations
why is having feathers that are less brightly coloured increase the survival rate of birds
would be less noticeable as they are camouflaged and therefore are less likely to be eaten by predators
why is more important for the survival of the species that survival rate is higher in female birds than male birds
females can reproduce however males can reproduce with multiple female birds
Describe how scientist can date stone tools using an information from where the tools were discovered
Use the soil and fossils around where the tool was found to identify how old the tool was -> the deeper in the soil the older the tools
Explain advantage of using biological control on a aphid populations
- chemicals don’t need to be used
- Less effect on biodiversity
- aphids will not be able to develop resistance to the chemicals
