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gcse biology > Harnessing Biology: Food Production > Flashcards

Harnessing Biology: Food Production Flashcards

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1
Q

how have different varieties of dog been produced?

A
  • through deliberate selective breeding by dog-owners
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2
Q

what are the steps taken to select a particular feature in an organism?

A
  1. choose individuals with the desired feature
  2. let only these individuals reproduce
  3. choose the offspring that have the desired feature
  4. let only these individuals reproduce
  5. repeat steps 3 and 4 until you have produced a variety in which all individuals show the desired feature.
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3
Q

what is the key to success with selective breeding?

A
  • is to identify the feature you want, only breed from the individuals that have that feature, and do not allow individuals with undesirable features to breed
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4
Q

what are some examples of what selective breeding can produce?

A
  • hens that lay big eggs of a particular colour
  • cattle that produce lots of meat
  • tomato plants that produce lots of tomatoes
  • crops that are resistant to certain plant diseases
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5
Q

what do farmers do to make a profit on their farms?

A
  • they try to control the environment in such a way as to maximise the yield from crop plants and livestock
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6
Q

what are the factors which affect photosynthesis?

A
  • light intensity
  • CO2 conc.
  • temperature
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7
Q

where do farmers grow crops and why?

A
  • in greenhouses
  • as in open fields it is very difficult to control the factors which affect photosynthesis and many others
  • greenhouses mean that farmers can have artificial heating, artificial lighting, additional CO2 in the air and regular watering
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8
Q

what provide enhanced conditions for plants to grow?

A
  • greenhouses
  • polythene tunnels
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9
Q

why do greenhouses and polythene tunnels provide enhanced conditions for plants to grow?

A
  • the transparent material allows sufficient natural light in for photosynthesis during the summer. additional lighting gives a ‘longer day’ during the winter for valuable crops
  • the greenhouse effect also raises the temperature in the glasshouses
  • burning fossil fuels or wood raises the temperature when the external temperature is too low. it also produces carbon dioxide and water vapour
  • water vapour maintains a moist atmosphere and so reduces water loss by transpiration
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10
Q

what do fertilisers provide?

A
  • elements needed by plants to grow such as nitrates for proteins and magnesium for the production of chlorophyll
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11
Q

what are the two types of fertilisers?

A
  • organic
  • inorganic
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12
Q

what is an organic fertiliser?

A
  • made from faeces of a range of animals, sometimes mixed with straw
  • also compost from legumes such as clover
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13
Q

what is inorganic fertiliser?

A
  • inorganic compounds carefully formulated to yield a specific concentration of a particular ion when applied according to the manufacturer’s instructions
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14
Q

what are the advantages of organic fertiliser?

A
  • improves soil structure
  • greater range of minerals
  • releases minerals over a longer period of time
  • less cost to farmer - already available on the farm
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15
Q

what are the disadvantages of organic fertiliser?

A
  • slow acting - has to be decomposed first
  • bulkier, so more difficult than inorganic fertilisers to apply
  • may contain pests
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16
Q

what are the advantages of inorganic fertiliser?

A
  • mineral ions release immediately so fast acting
  • contents known
  • easy to apply
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17
Q

what are the disadvantages of inorganic fertiliser?

A
  • can lead to eutrophication as fertiliser is soluble
  • requires regular application
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18
Q

what is a way to replace lost nitrates?

A
  • to grow a legume crop, such as clover, in a field one year in four
  • these plants have nitrogen-fixing bacteria in nodules on their roots
  • they convert nitrogen gas in the air into ammonium ions
  • some of this is passed to the plants, which use it to make proteins
  • in the autumn, the crop is ploughed in and when the protein in the crop and bacteria is broken down (decomposed) ammonium is released into the soil
  • the ammonium is then converted to nitrate by nitrifying bacteria and is available to next years’ crops
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19
Q

what are pests?

A
  • pests are organisms that reduce the yield of crop plants or stock animals
  • by doing this they cause economic damage to the farmer
  • any organism can be a pest
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19
Q

how are pesticides names?

A
  • according to the type of organism they kill
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19
Q

how can pests be controlled?

A
  • chemicals called pesticides
  • use another organism to reduce the numbers of a pest- biological control
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20
Q

what do herbicides kill?

A
  • plant pests
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21
Q

what to insecticides kill?

A

insects

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22
Q

what do fungicides kill?

A

fungi

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23
Q

what do molluscicides kill?

A
  • molluscs (e.g. slugs and snails)
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24
Q

what do pesticides do?

A
  • used to kill specific pests and so improve the yield from the crops and livestock
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25
Q

when are pests a problem?

A
  • when they are present in sufficient numbers to cause economic damage
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26
Q

when should you use pesticides?

A
  • when or when not to use them is a financial decision, the increase in income must be set against the cost of the pesticide
27
Q

what are the disadvantages of pesticides?

A
  • they may also damage ecosystems as often the pesticide molecules are simply passed higher up the food chain, becoming concentrated in the tissues of top carnivores
28
Q

what does the biological control method use?

A
  • a predator species rather than a toxic chemical, to reduce the numbers of a pest
29
Q

how can whiteflies in a greenhouse full of tomato plants be controlled?

A
  • by introducing a tiny parasitic wasp called Encarsia
  • these lay their eggs inside the larvae of the flies, which hatch and then eat the larvae and so reduce the numbers of whitefly
30
Q

what is a feature of biological control?

A
  • it never eradicates a pest
  • if the organism killed off all of the pests then it too would die from lack of food
  • the aim is to reduce pest numbers to a level where they no longer cause significant economic damage
  • many can be mail-ordered, keeping their population high
31
Q

draw a graph showing the effect of a biological control agent on pest levels.

A
  • bio rev image
32
Q

what is the effect of introducing a natural predator?

A
  • ladybirds can be used to control the populations of aphids in orange groves
33
Q

what is the effect of introducing a herbivore?

A

herbivore (e.g. moth) eats pest plant such as prickly pear cactus in Austrailia

34
Q

what is the effect of introducing a parasite?

A
  • wasp encarsia lays its eggs in whitefly eggs and reduces the population
35
Q

what is the effect of introducing a pathogenic microorganism?

A
  • a fall in pest numbers - such as that caused by the myxomatosis virus on rabbit population in Austrailia
36
Q

what is the effect of introducing sterile males?

A
  • mate with females but to produce no offspring, so pest numbers fall
37
Q

what is the effect of using pheromones?

A
  • sex hormones released to attract males or females which are then collected and destroyed, reducing the reproductive potential of the population
38
Q

what are the methods of biological control agents?

A
  • introduce a natural predator
  • introduce a herbivore
  • introduce a parasite
  • introduce a pathogenic microorganism
  • introduce sterile males
  • using pheromones
39
Q

what are the advantages to pesticides?

A
  • reduces pest population instantly
  • can kill the whole population of pests
40
Q

what are the disadvantages to pesticides?

A
  • cost (need for regular applications)
  • not specific e.g. will kill predaceous insects and pollinating insects in addition to the pest
  • pest can become resistant to chemical
  • chemical can concentrate in all organisms higher up in the food chain
41
Q

what are the advantages to biological control?

A
  • organism only introduced once as it will reproduce
  • only one cost for the initial introduction
  • pest specific - only kills the pest
  • pest will not become resistant
  • no effect on other animals in the food chain
42
Q

what are the disadvantages to biological control?

A
  • takes time to reduce pest population
  • not all population killed
  • expensive if re-populating is required
43
Q

where does anaerobic respiration happen?

A
  • in some plant cells, animals and some microorganisms such as yeast
44
Q

when is anaerobic respiration in yeast used?

A
  • during beer brewing
  • during bread making
45
Q

what is the equation for anaerobic respiration in yeast?

A
  • glucose -> ethanol + carbon dioxide
  • C6H12O6 -> 2C2H5OH + 2CO2
46
Q

what is ethanol?

A
  • the alcohol found in alcoholic drinks like beer and wine
47
Q

how does anaerobic respiration aid bread-making?

A
  • bubbles of CO2 gas expand the dough and help the bread rise
  • the high temperatures used in bread making mean that the ethanol does not remain in the bread after cooking has finished (it has evaporated)
48
Q

how do you investigate anaerobic respiration in yeast?

A
  • to study the production of CO2 under different conditions
  • in the presence of CO2, limewater turns cloudy white and the hydrogen carbonate indicator changes from orange to yellow
49
Q

describe the experiment to investigate anaerobic respiration in yeast using the production of CO2 under different conditions.

A

METHOD:
- set up the apparatus as shown below
- *bio rev image
1. dissolve sugar in previously boiled water
2. add yeast and mix to form a suspension, and pour into a boiling tube
3. add a layer of vegetable oil
4. connect a delivery tube to a second boiling tube, this time containing limewater or hydrogencarbonate indicator
EXPLANATION:
- the layer of veg oil prevents oxygen from entering the mixture, while allowing carbon dioxide to escape
- this ensures that anaerobic respiration is taking place
- it usually takes an hour or so for fermentation to be visible
- the number of bubbles over a set time can be counted, or the appearance of the indicator can be compared to a control containing boiled (dead) yeast

50
Q

what are the conditions that can be investigated using the experiment to investigate anaerobic respiration in yeast using the production of CO2 under different conditions.

A
  • temperature
  • conc of sugar
  • type of sugar
51
Q

what do many microorganisms produce?

A
  • extremely useful chemicals that can be used in medicine
52
Q

what are examples of microorganisms which produce extremely useful chemicals that can be used in medicine?

A
  • the fungus penecillium produces the antibiotic penicillin
  • bacteria can be genetically engineered to produce the human insulin
53
Q

what are fermenters used for?

A
  • to grow these microorganisms on an industrial scale
54
Q

label the diagram.

A

*bio rev image

55
Q

what is the function of the cooling jacket?

A
  • removes heat energy, stopping the fermenter overheating and enzymes denaturing
56
Q

what is the function of the air filter?

A
  • filters air coming in, maintaining sterile conditions
57
Q

what is the function of a stirrer?

A
  • keep the broth well stirred to oxygenate all parts of the fermenter and prevent micro-organisms settling
58
Q

what is the function of a growth medium?

A
  • contains all necessary glucose and amino acids for micro-organism growth
59
Q

what is the function of super-heated steam?

A
  • applied before the fermenter is used, killing unwanted micro-organisms. leaves only water with no other residue
60
Q

how is yoghurt made?

A
  • using the bacteria Lactobacillus bulgaricus
    METHOD:
    1. the equipment is sterilised
    2. the milk is pasteurised by heating
    3. the bacterial culture is added to the cooled milk and left at 46 degrees celcius for about four hours
    4. samples are taken if the yoghurt is ready
    5. flavours and colours are added, then the yoghurt is packaged
61
Q

how does lactobacillus create yoghurt?

A
  • respires anaerobically, producing lactic acid
  • this lowers the PH, acting as a preservative
  • the acid also coagulates the milk protein, as the acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour
  • finally the yoghurt is further cooled at 5 degrees celcius to help preserve the yoghurt
62
Q

why is fish farming now meeting a shortfall in fish?

A
  • as stocks in the wild have been depleted
  • the more commonly farmed fish are the more commercial species such as salmon and trout
  • some of the fish are used to make animal feed
63
Q

what do farmers feed the fish?

A
  • a high lipid and protein food to promote rapid growth, as well as regular feeding with small amounts so that most gets eaten
64
Q

what happens if you put several species of fish in one pond - PROBLEM ONE, PROBLEM TWO AND SOLUTION?

A

PROBLEM ONE: interspecific competition
- different species will compete for food and some species may be wiped out
PROBLEM TWO: predation
- carnivorous species will prey on other fish
SOLUTION:
- place different species in different ponds, tanks, etc
- use nets to separate species and wild/farmed populations

65
Q

what happens if you put too many individuals in one pond - PROBLEM ONE, PROBLEM TWO AND SOLUTION?

A

PROBLEM ONE: intraspecific competition
- larger individuals will out-compete smaller individuals for food or larger individuals may prey on smaller individuals
PROBLEM TWO: infectious diseases
- parasites and pathogens spread quickly if the fish are too close together
SOLUTION:
- separate fish by age and size
- remove dead/infected fish quickly and add antibiotics to the water to kill bacteria
- add antifungals or chemicals to kill parasites

66
Q

how do fish farms affect the environment?

A
  • fish may escape and out-compete or interbreed with local species reducing biodiversity and/or upsetting the local ecosystem
  • parasites or pathogens can be introduced into ecosystems by farmed fish
  • excess feed and waste from fish can cause eutrophication and a reduction in oxygen conc. in water (reduced by limiting feed, clearing, waste and bubbling oxygen through water)

gcse biology (24 decks)

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