food production Flashcards

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1
Q

advantages of organic fertilisers

A
  • improves soil structure
  • greater range of minerals
  • releases minerals over a longer period of time
  • cheaper- available on farm
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2
Q

disadvantages of organic fertilisers

A
  • slow- has to decompose first
  • bulkier- harder to apply
  • may contain pests
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3
Q

advantages of inorganic fertilisers

A
  • mineral ions released immediately- fast acting
  • contents known
  • easy to apply
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4
Q

disadvantages of inorganic fertilisers

A

-can lead to eutrophication

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5
Q

nitrogen fixing plants

A

legume crops used- have nitrogen-fixing bacteria in nodules on their roots, convert nitrogen gas in air to ammonium ions
passed to plants- use to make proteins
when crop is ploughed- protein decomposed and ammonium us released into soil- converted to nitrate by nitrifying bacteria

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6
Q

how do pesticides improve yield from crops and livestock

A

herbicides- plant pests
insecticides- insects
fungicides- fungi
molluscicides- molluscs(slugs/snails)

damage ecosystem- molecules passed higher up in food chain- concentrated in tissues of top carnivores

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7
Q

how does biological control reduce the numbers of pests

A

uses predator species

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8
Q

biological control agents

A

natural predator- ladybirds control aphid population in orange groves

herbivore- moth eat prickly pear cactus Australia

parasite- wasp encarsia lay eggs in whitefly eggs and reduces population

pathogenic microorganism- myxomatosis virus on rabbit pop in aus

sterile males- mate with females- no offspring- reduce pet numbers

pheromones- sex hormones released- males and females collected and destroyed reducing reproductive potential of pop

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9
Q

advantages and disadvantages of pesticides

A
  • reduces pest pop instantly
  • kills whole pop
  • cost
  • not specific
  • pest can become resistant
  • chemical concentrates in organisms higher in food chain
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10
Q

advantages and disadvantages of bio control

A
  • organism introduced once
  • one cost
  • specific
  • pest not resistant
  • no effect on other animals in food chain
  • time to reduce pop
  • not all killed
  • expensive repopulating
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11
Q

cooling jacket

A

removes heat energy, stopping fermenter overheating and enzymes denaturing

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12
Q

air filter

A

filters coming in air, maintains sterile conditions

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13
Q

stirrers

A

keeps broth well stirred to oxygenate fermenter and prevent microorganisms settling

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14
Q

growth medium

A

contains glucose and amino acids for microorganism growth

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15
Q

super-heated steam

A

applied before fermenter used, kills unwanted microorganisms, leaves only water with no residue

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16
Q

fish farming

A

farmers feed fish high lipid and protein diet- promote rapid growth
regular feeding with small amounts- most is eaten

17
Q

what happens if you put several species in one pond?

A
  • interspecific competition- different species compete for food, some species wiped out
    predation- carnivorous species prey on other fish
    solution; place different species in different ponds, cover over ponds- reduce predation from birds
18
Q

what happens if you put too many individuals in one pond?

A

-intraspecific competition- larger individuals will out-compete smaller for food or pray on smaller
infectious diseases- parasites and pathogens spread quickly if too close

solution; separate by age and size, remove dead or infected quickly and add antibiotics to water to kill bacteria

19
Q

how do fish farms affect environment

A
  • escape and out-compete or interbreed with local species reducing biodiversity and upset local ecosystem
  • parasites or pathogens introduced into ecosystem by farmed fish
  • excess feed and waste- eutrophication