5 Food production Flashcards

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1
Q

What do greenhouses allow farmers to have?

A

artificial heating, lighting
additional carbon dioxide in air
regular watering

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2
Q

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

A

transparent material allows sufficient natural light for photosynthesis during summer
Greenhouse effect raises temp in glasshouses
Burning fossil fuels or wood raises temp when external temp is too low - and produces CO₂ and water vapour
Water vapour maintains moist atmosphere, reducing water loss by transpiration

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3
Q

What do the enhanced conditions in glasshouses/polythene tunnels increase?

A

rate of photosynthesis and therefore yield
Farmer must find optimum conditions

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4
Q

What are the two types of fertilisers? What are they made from?

A

organic:
faeces of a range of animals, sometimes mixed with straw. Also compost from legumes such as clover

inorganic:
inorganic compounds carefully formulated to yield a specific concentration of a particular ion

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5
Q

What do fertilisers provide?

A

elements needed by plants to grow such as nitrates for proteins and magnesium for production of chlorophyll

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6
Q

What are the advantages/disadvantages of organic fertilisers?

A

Adv:
Improves soil structure
Greater range of minerals
Releases minerals over longer period of time
Less cost

Dis:
Slow acting
Bulkier, more difficult to apply
May contain pests

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7
Q

What are the advantages/disadvantages of inorganic fertilisers?

A

Adv:
Mineral ions release immediately so fast acting
Contents known
Easy to apply

Dis:
Can lead to eutrophication as fertiliser soluble
Requires regular reapplication

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8
Q

How do nitrogen fixing plants increase crop yield?

A

Legume crop, such as clover
contain nitrogen-fixing bacteria in nodules on roots
convert nitrogen gas to ammonium ions
Some passed to plants to make proteins
When crop and bacteria decomposed (crop ploughing), ammonium released into soil - converted to nitrates by nitrifying bacteria

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9
Q

What are pests?

A

organisms which reduce yield of crop plants or stock animals - economic damage to farmer

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10
Q

How can pests be controlled?

A

Chemicals called pesticides
Using another organism (Uses predator species) to reduce numbers of a pest - biological control

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11
Q

What are the names for pesticides?

A

Herbicides kill plant pests
Insecticides kill insects
Fungicides kill fungi

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12
Q

How do pesticides improve yield?

A

kill specific pests

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13
Q

Why does biological control never eradicate a pest?

A

If organism killed off all pests, it would die from lack of food
Aims to reduce pest numbers to level where no longer cause significant economic damage

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14
Q

What are the methods of biological control?

A

Introduce natural predator: Ladybirds control pop of aphids in orange groves

Herbivore: moth eats pest plant such as prickly pear cactus

Parasite: encarsia lay eggs in whitefly eggs and reduces pop

Sterile males: mate with females but produce no offspring, so pest numbers fall

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15
Q

What are the advantages/disadvantages of pesticides?

A

Adv:
reduces pest population
can kill whole population of pests

Dis:
Cost (regular reapplication)
Not specific (can kill pollinating insects as well)
Pest can become resistant
Chemical can concentrate in all organisms higher up food chain

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16
Q

What are the advantages/disadvantages of biological control?

A

Adv:
Organisms only introduced once as will reproduce
Only cost for introduction
Pest specific
Pests can’t become resistant
No effect on other animals in food chain

Dis:
Takes time to reduce pest pop
Not all pop killed
Expensive if re-populating required

17
Q

When is anaerobic respiration in used used?

A

during beer brewing and bread-making

18
Q

What is the word and symbol equation for the anaerobic respiration of yeast?

A

glucose → ethanol + carbon dioxide
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

19
Q

What makes bread rise?

A

bubbles of carbon dioxide gas expand the dough

20
Q

What do the high temperatures in break making mean?

A

ethanol does not remain in bread after cooking finished (evaporated)

21
Q

Describe the method to investigate anaerobic respiration by yeast

A

Dissolve sugar in previously boiled water
Add yeast and mix to form a suspension, and pour into a boiling tube
Add a layer of vegetable oil
Connect delivery tube to a second boiling tube, this time containing limewater
Count number of bubbles over a set time

Investigate these conditions:
temperature
concentration of sugar
type of sugar

22
Q

Why is the layer of vegetable oil needed in investigation?

A

prevents oxygen entering the mixture, allows carbon dioxide to escape
ensures it’s anaerobic respiration taking place

23
Q

What micro-organisms can a fermenter grow on an industrial scale?

A

the fungus penicillium produces antibiotic penicillin

bacteria can be genetically engineered to produce human insulin

24
Q

What are the parts of a fermenter?

A

cooling jacket
air filter
stirrers
growth medium
super-heated steam

25
Q

What does the cooling jacket do?

A

Removes heat energy, stopping the fermenter overheating and enzymes denaturing

26
Q

What does the air filter do?

A

Filters air coming in, maintaining sterile conditions
no bacteria - prevents contamination

27
Q

What do the stirrers do?

A

Keep broth well stirred to oxygenate all parts of fermenter and prevent micro-organisms settling

28
Q

What does the growth medium do?

A

contains all necessary glucose and amino acids for micro-organism growth

29
Q

What does the super-heated steam do?

A

Applied before fermenter used, killing unwanted micro-organisms. Leaves only water with no other residue
makes aseptic conditions

30
Q

What bacterium is used to make yoghurt?

A

lactobacillus bulgaricus

31
Q

How is yoghurt made?

A

Milk is pasteurised (heated) to kill unwanted bacteria, then cooled
After cool, Lactobacillus added and the mixture is maintained at 46ºC, ensures bacteria’s enzymes not denatured

32
Q

How does Lactobacillus help make yoghurt?

A

Respires anaerobically producing lactic acid. Lowers pH, acting as a preservative. Acid also coagulates the milk protein, as acidic conditions change the shape of the proteins, giving yoghurt its texture and flavour

33
Q

What helps preserve the yoghurt?

A

further cooled to 5ºC