Natural Selection & Genetic Modification Flashcards
Why are the cells from birds described as eukaryotic?
• they have membrane-bound organelles
The three domain classification system was suggested for..
• genetic analysis
• based on DNA/genetics
• domain theory is based on genetics
• differences between coding & non-coding DNA
The domain that plants belong to is..
Eukarya
What happens in a chloroplast?
• oxygen produced
• sunlight absorbed by chlorophyll
Describe the evidence how Ardi ramidus inhabited Earth earlier than Homo habilis
• differences in structural features of fossil (smaller cranial capacity)
• Ardi would be deeper in rock layer than Homo (stone tools)
Suggest an explanation for the extinction of Homo habilis
• out-competed by Homo erectus
• for resources essential for survival/due to presence of a new selection pressure
Define evolution
• Evolution is the change of inherited characteristics through natural selection.
• these changes occur because genes mutate
Describe how the thinner beak of species A is a result of evolution
• variation in beak shape/mutations occured that changed shape of beak
• thinner beaks more suited to environment
• birds with thinner beaks more likely to survive
• more birds with thinner beaks reproduced + passed on alleles for thinner beaks
• occurs over many generations
Describe how stone tools & fossils can be dated to find out how old they are
• compare with other tools/fossils (that have already been dated)
• from the layer of rock it was found in/how deep down each was found
• radiometric dating
Explain how bacteria has become resistant to Colistin
• people don’t finish their course
• natural selection/evolution occurs
• some bacteria has mutation /
genetic variation
• resistant bacteria survive / resistant bacteria reproduce
The theory of evolution suggests…
new species evolve over many generations
Explain how bacteria developed resistance to antibiotics
• by natural selection/evolution
—> mutation in bacterium / variation in population
• only resistant bacteria survived treatment by antibiotics / survives when people don’t finish course
• resistant bacteria reproduce
• offspring inherit resistance
State how the use of antibiotics contributes to bacteria developing resistance to antibiotics
People not completing their course of antibiotics / overuse of antibiotics
Describe how structure of limbs provide evidence for evolution
• pentadactyl limb
• suggests a common ancestor
• that also had a pentadactyl limb
• structure has been adapted to different functions
Describe the theory of evolution by natural selection
• organisms in a species have variation / mutations
• there is a selection pressure / competition for resources (food)
• organisms most adapted to environment survive
• reproduction leads to offspring inheriting characteristics
• repeated over generations
Explain how MRSA bacteria have evolved to become resistant to antibiotics (6 marks)
• bacteria reproduce rapidly generating a large population
• variation in bacterial population
• some bacteria develop resistance to antibiotics through mutation
• bacteria resistant to antibiotics survive
• antibiotic resistance is inherited
• non-resistant bacteria doesn’t survive
Explain why having less brightly coloured feathers increases the survival rate of females
• they are camouflaged
• therefore they’re less likely to be eaten by predators
• more likely to get food from prey
Suggest why it’s more important for the survival rate in female birds to be higher than male birds
• females produce offspring/lay eggs
• one male bird can reproduce with many female birds
(increases population of birds)
State how fossils can be dated
• location in rock layer
• radiometric dating
• stratigraphy
Describe reasons why the anatomy of pentadactyl limbs suggests that bats & cats evolved from a common ancestor
• same bone structure
• common ancestor had pentadactyl limb structure / similar limb structure
Scientists can sequence genes from different organisms.
Describe how genetic analysis provides evidence for evolution
• compare genes/sequence of genes from different organisms
• closely related organisms have similar sequences / organisms with similar genes share a common ancestor
Describe how scientists can produce a genetically modified bacterium that produces penicillin (4)
• use restriction enzymes to remove the gene & cut plasmid
• use ligase enzymes to join DNA molecules together
• cut the gene from the genome of the fungus & extract a plasmid from bacteria
• insert recombinant plasmid back into bacteria
Describe how cattle can be selectively bred to produce cattle that can survive high temperatures & have good meat quality
• breed cattle with better characteristics
• select offspring with desired characteristics & breed them
• repeat over many generations
Describe how drought-resistant crops plants can be produced
• genetic variation - some plants will be more adapted to drought conditions & these can be selected
• cross-pollinate these plants & grow seeds under drought conditions
• select offspring & repeat over many generations
Describe how racehorses alive today have been selectively bred to run faster (3)
• breed two animals that can run fast
• select offspring that can run fast
• repeat process over many generations
Explain how bacteria can be genetically engineered to produce human insulin (6 marks)
• gene that codes for human insulin is identified
• in human DNA
• this is removed using a restriction enzyme
• plasmid of a bacterial cell is removed
• using lysosomes/lysozyme
• using same restriction enzyme
• leaving complementary sticky ends
• human gene is inserted into bacterial plasmid
• using ligase enzyme
• plasmid returns to bacterial cell
• bacterial cell multiplies
Explain how enzymes are used to produce a genetically modified plasmid in a bacterial cell (3 marks)
• plasmid & gene are cut using restriction enzymes
• these enzymes produce complementary sticky ends/base pairs
• gene is inserted into plasmid using ligase
Explain advantages of producing genetically modified crop plants
• less crop damage
• so higher yield
• so more food for people
• crop plants less likely to have diseases that are spread by insects
• so less pesticides/insecticides used
• more profit
• so more income for developing countries
increases yield
• can be produced in a shorter time period
• production is cheaper/easier to extract
• takes up less space than growing plants
Explain disadvantages of producing genetically modified crop plants
Less variation
• concerns about long term effects
• GM crops can cause diseases to humans
• GM crops could trigger allergic reactions
• genes could be transferred to other species/weeds
• so weeds could grow out of control
• reduced gene pool
• insects will evolve so crops are no longer resistant to insect pests
• concerns over genetically modified yeast being manufactured illegally
• may not be as effective/identical
• concerns over GM organisms entering environment
ExplIn one advantage of producing genetically modified crops that produce toxic chemicals in their leaves (2 marks)
• kills insects/pests/pathogens
• less damage to crops / increases crop yield
• no need to use insecticides/pesticides
If GM crops have a large yield…
Less land is needed to grow GM crops
