B6.2 - Feeding The Human Race Flashcards
Food security
The ability of human populations to access affordable food of sufficient quality & quantity
Factors threatening food security
- increasing human population
- changing diets (more wealth = more varied diet, more meat than plants)
- climate change (global warming will cause more droughts & deserts will expand, more co2 in atmosphere = increased yield of crops)
- new pests & pathogen may evolve
How can farmers increase food production
- maximise photosynthesis: light levels, temp, water supply controlled in industrial glasshouses
- fertilisers: as plant grows minerals removed from soil, fertilisers help land remain fertile
- removing competition & pests: herbicides - kill weeds, insecticides - remove insects, fungicides - destroy disease-causing fungi
- planting varieties of crops that are pest resistant / produce higher yield
Intensive farming techniques
- using fertilizers & pesticides to aid plant growth
- maximising animal growth rates
- maximising labour inputs by using machinery
(Produces maximum food product yield from minimum area of land)
Organic farming
Uses more natural methods of producing crops & rearing animals
Avoids use of artificial chemicals
Yields generally smaller so products may be more expensive
Fish farming
- fish bred/reared in large cages in sea/rivers
- protects fish from predators, easier to catch, allows wild populations to recover
- if fish kept close together, disease can spread quickly
Sustainable farming techniques to minimise fertilisers/pesticides
- replace soil nutrients by spreading manure
- crop rotation: planting different crops each year, soil can recover,
- gene technology: developing crop varieties more resistant to pests/disease
- biological control: using a natural predator to control a pest population (predators bred in large numbers, released onto crops, eat pests )
Hydroponics
Growing plants in water containing dissolved minerals
commercial growers ensure plant receives needed mineral, plants grow quickly eg, in glasshouse
Selective breeding
Breading animals and plants for particular characteristics
Why is selective breeding done
- to produce highest yield (choose best plants/animals to breed)
- to feed our increasing population (plants)
- to produce crops with high resistance to disease
How does a a farmer selectively breed organisms
- Decide which characteristic of species is desirable
- Select parents with high levels of this characteristic
- Breed from these individuals
- Select best offspring, breed again
- Repeat for many generations
New characteristics of wheat due to selective breeding
- larger ears with many seeds
- stronger stalks that ears stay on
- ears ripen at same time
- stalks grow to same heigh
Disadvantages of selective breeding
- reduces no. of alleles (gene pool) of a species, reduces variation
(If new disease arises, may not be organism in existing gene pool containing allele resistant to disease so species may become extinct) - increases chance of inheriting genetic disease
Gene pool
All the genetic material present in a population
Genetic engineering
Scientists altering an organisms genome to produce an organism with desired characteristics
Examples of genetic engineering in agriculture
- Cotton: to increase crop yield from same area of land
- Corn: to produce toxins that kill insects, makes plant resistant to pests, less pesticides needed
- Bacteria: to produce medical drugs (insulin) / drugs to treat diseases in domesticated animals
How do scientists produce a genetically engineered organism
- removes genes that code for desired character tics (foreign genes)from donor organism
- insert foreign genes into plant/animal cells at early stage of host organisms development
- as host organism develops, displays characteristics coded for by foreign genes
Risks of genetic engineering
- eating genetically engineered organisms may lead to health problems (may introduce new allergens)
- genetically engineered crops may cross-pollinate with wild plants, introducing new gene into wild plants, could disrupt balance of an ecosystem
- some feel it is unethical (science interfering with nature)
Scientists genetically engineer bacteria to produce…
- hormones (insulin)
- vaccines
- antibodies
What enzymes are used to move a gene between genomes during genetic engineering
- restriction enzymes:
- ligase enzymes:
Restriction enzymes
- cut donor DNA at specific base sequences
- make staggered cut, leaving few exposed unpaired bases on ends of DNA strands = sticky ends
- same restriction enzymes cut open bacterial plasmid
Ligase enzymes
- rejoin DNA strands at sticky ends
- host & donor DNA have same sticky ends = new gene joined into plasmid DNA
Insulin
Hormone which stimulates liver to turn glucose into glycogen,
decreasing blood sugar levels
Genetic engineering of bacteria to insulin
- insulin gene removed from human DNA by restriction enzymes
- plasmid (loop of bacterial DNA) removed from bacterial cell
- plasmid cut open using same restriction enzyme
- human insulin gene inserted between cut ends of plasmid using ligase enzyme, plasmid = vector as carries human gene
- repaired loop of DNA inserted into new bacterium = transgenic bacteria (have DNA from another organism)
- transgenic bacteria grown in large numbers to produce insulin
