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b6 (genetic engineering (move genes for desirable characteristics from one…
b6
genetic engineering
move genes for desirable characteristics from one organism to another, changing the genome in the process
vectors used to transfer DNA into a cell, plasmids often used, small circular molecules of DNA transferred between bacteria
DNA for the desired characteristic is cut out with a restriction enzyme which recognises specific sequences of DNA and cut the DNA at these points
plasmid cut upoen using same restriction enzyme, creates sticky ends on the DNA, short tails of unpaired bases complementary to each other
plasmid and DNA inserting are mixed together w ligase enzymes, ligases join the sticky ends of the two pieces of DNA together
plasmid vectors contain new DNA inserted into other cells eg bacteria, called hosts, host cells can use inserted gene to produce desired characteristic, select and identify individuals that have successfully recieved desired gene
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selective breeding
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maximum yield of meat, milk, grain so food production is high as possible
good health, disease resistance
temperament, speed, fertility, attractive flowers, nice smell
parent organisms with the best characteristics are selected, bred with eacher other, best of the offspring selectred and bred, repeated over many generations to develop desired traits
can also combine two desirable characteristics, cross breeding
food security factors
changing diets in wealthier populations : wealthier people's diets more likely to change to include a wider variety of foods, eg more people eating meat which is expensive, increased demand is bad as for a given area of land, you can produce more food via crops than by grazing animals, animals to be eaten often fed brops humans could have eaten
new pests and pathogens : can result in loss of crops or livestock and could lead to widespread famine
sustainability : meeting the needs of today's population without harming the environment so that future gens can meet their needs, unsustainable methods to produce food
environmental change : increased temp can affect growth pattern of crops, reduction in yield, rising sea levels reduce land available for food production, pollution
cost : agriculture relies on fuel for transport, chemicals for fertilisers and pesticides, animal feed etc, high input costs can make it too expensive for some countries to start or maintain, not enough food to feed everyone, unaffordable prices
environmental changes
can cause change in distribution, change in where an organism lives
change in availability of water : distribution of animal and plant species in the tropics changes between wet and dry seasons
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global warming
temp of earth is a balance between energy from sun and energy radiated back into space, gases in the atmosphere act naturally as an insulating layer
gases absorb most of the energy normally radiated out into space, re-radiate in all directions including back to earth, increases temp
several gases in the atmosphere that keep energy in, greenhouse gases, main ones are carbon dioxide and methane because their levels are sharply rising
average temp gradually increasing because of rising levels, global warming, type of climate change and causes other types like changing rainfall patterns
consequences
higher temp cause seawater to expand and ice to melt, raises sea level, if it keeps rising will cause harm to people and animals living in low-lying places, flooding, loss of habitat
distribution of wild animal and plant species may change, amount of rainfall will change, species that need cooler temps have smaller ranges
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fertilisers
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if they don't have enough, growth and life processes affected, maybe used up by previous crop planted in the same soil
fertilisers replace missing elements or provide more, increase crop yield, boosts plant growth
can cause problems, can run off fields and end up in ponds, rivers and lakes, result in death of organisms in the water
pesticides
form of chemical pest control, sprayed on crops, poisonous to humans, must be used carefully to keep amount in food below a safe level
insecticides = insects, herbicides = unwanted plants, fungicides = fungi
can harm other wildlife like bees, can cause shortage in food for animals higher in the food chain
some stick around, can be passed along food chain, kill organisms higher up, can end up consuming lots of pesticide that has accumulated in lower organisms
hydroponics
plants grown in nutrient solutions, not soil, can be supported and have roots in solution, or planted in a growth medium like gravel, coir or perlite
glasshouse tomatoes, salad crops on commercial scale or areas where it's had to grow plants in soil
pests and diseases effectively controlled, nutrient levels precisely controlled for maximum growth, higher yields
lots of fertilisers, expensive, disesase could spread quickly and cause a lot of damage
biological control
involves using other organisms to reduce number of pests, encourages wild organisms or adds new ones
could be predators, eg ladybirds eat aphids, parasites, eg flies lay eggs on slugs, killing them, or disease causing, eg bacteria that affects caterpillars
can have a longer lasting effect, less harmful to wildlife, can cause problems but considered safer alternative, no chemicals, less pollution and risk to people, no chemicals passed in food chain
genetic modification
transfer useful genes to plants and animals, useful characteristics of inserted gene
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can be made insect resistant, virus resistant, herbicide resistant
reduction in gene pool
selective breeding reduces the gene pool, less different alleles in a population
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serious problems if a new disease appears, not much variation, if all closely related, if one is killed, all likely to die
food security
rapid population increase means global food production must increase, need access to enough food safe for us with the right balance of nutrition = food security
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