Unit 4

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  • Created by: sally
  • Created on: 27-05-13 20:10
What is autotrophic nutrition?
Biological processes reliant on respiration
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What is heterotrophic nutrition?
Organisms that cannot create their own energy so get it from eating other organisms.
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Abiotic factors that affect food productivity?
nutrient/water supply, temperature, light, acidity, CO2
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Biotic fatcors that affect food productivity?
population control, reduction of competition, increasing population of desired species
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What factors influence the selection of species for cultivation?
water supply, temperature, wind velocity, light, topography, altitude, soil, pest problems, market demand, farm size, labour cost, grants, technology.
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What are the advantages of asexual reproduction?
Survival of young plants is higher, genetically identical so have the same characteristics.
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What are the disadvantages of asexual reproduction?
No room for genetic improvement, small number of offspring.
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What are the advantages of GM crops?
allo desirable characteristics to be produced, no need for pesticides if pest resistant.
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What are the disadvantages of GM crops?
Pollen could be toxic to other plants and insects, horizontal gene transfer, allergies
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What are the advantages of gibberelins?
inhibit shoot growth for cereals, stimulate seed germination, inhibit root growth, increase fruit size.
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How can pests cause damage?
reduce harvest and crops and livestock, reduce quality, cause human disease.
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When is pest control needed?
In monoculture and intensive rearing.
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What are the properties of pesticide?
specificity, persistence, toxicity and bioaccumulation/biomagnification
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How do weeds reduce crop yields?
competing for nutrients, contaminating crop, providing food for pests.
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What do hormone herbicides do?
Kill weeds by modifying the growth and development of the plant.
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What do contact herbicides do?
Scorch the leaves on contact damaging cells and leaf surface.
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How do insects reduce crop yields?
eat the crop, spoil appearance, spread diseases
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Why are livestock given antibiotics?
to control infections, prevent infections, increase growth
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How can we control pests without pesticides?
Crop rotation, mulching, barrier crops, sowing density, sowing date, pheromone traps, biological control.
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What are the main principles of integrated control?
use cultural techniques, use appropriate non pesticide techniques, cultivating species less likely to suffer pest attacks.
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What abiotic factors must be controlled to increase productivity?
temperature, light, CO2, water, nutrients
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What are the cultural methods of managing nutrient supplies?
nitrogen fixation, crop rotation
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Advantages of natural fertilisers?
release nutrients gradually, cheap, provide food for soil biota, increase humus
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Disadvantages of natural fertilisers?
application will not supply large amounts, hard to transport as bulky, nutrient content cannot be controlled.
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Advantages of artifical fertilisers?
nutrient content can be controlled, mechanical application is easy, available for crop use as soon as applied
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Disadvantages of artifical fertilisers?
Do not add humus, not provide food for soil biota, expensive, can be washed off.
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What are the environmental impacts of soil erosion?
habitat loss, pollution, change to the hydrological cycle, accelerated soil erosion,
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What problems are caused by soil erosion?
reduced productivity, landslides, flooding, coastal sedimentation.
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How can we reduce soil erosion?
cultivation of long term crops, not cultivating steep slopes, terracing, contour ploughing, windbreaks,mulching
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What are the social impacts of agriculture?
uneven distribution of food, misuse of the land
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How do we reduce food surpluses?
Quoats, farm diversification, set aside.
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Why is estimating the MSY hard?
Need to collect difficult info such as current total biomass, annual biomass, breeding and survival rates.
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What is pelagic fishing?
Fish in mid water or surface, a drift net pulled in.
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What is demersal fishing?
Fish that live on or just above the sea bed, a longline or bottom trawl is used.
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What are the environmental impacts of fishing?
Bycatch, seabed disturbance, food web disturbed, ghost fishing
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Strategies to reduce overfishing?
quotas, no take zones, reduce net size, closed seasons, protected species, population seeding.
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What are the principles of aquaculture?
selection of desirable species, control of undesriable species, the provision of food, control of abiotic factors
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What methods are used in aquaculture?
extensive, intensive
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What limiting factors are controlled in aquaculture?
temperature, dissolved oxygen, water flow rate, pests, light levels.
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What are the environmental impacts of aquaculture?
overfishing, predation control, parasites, gene pool contamination, pollution, introduced species.
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What are the main features of tropical plantations?
habitat loss, monoculture production, species selection, selective breeding.
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How can the MSY be increased?
select species that grow quickly, control tree spacing, control pests/predators, increase nutrient supplies, selective breeding to enhance growth
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What are the causes of deforestation?
Logging, farming, urban expansion, mineral extraction, reservoirs/HEP schemes, roads.
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What are the consequences of deforestation?
reduced biodiversity, soil erosion, loss of carbon storage, reduced rainfall, increased ground albedo, loss of visual amenity
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What attempts have their been to increase sustainability?
Stockholm conference 1972, Brundtland commision 1983, Rio summit 1992, Rio + 10 2002, protect species and habitats.
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What factors make recycling more difficult?
mixed materials, transport, labour costs, dispersal
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Strategies to make recycling more easy?
Labelling, design for end life, reusing end parts
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Other cards in this set

Card 2

Front

What is heterotrophic nutrition?

Back

Organisms that cannot create their own energy so get it from eating other organisms.

Card 3

Front

Abiotic factors that affect food productivity?

Back

Preview of the front of card 3

Card 4

Front

Biotic fatcors that affect food productivity?

Back

Preview of the front of card 4

Card 5

Front

What factors influence the selection of species for cultivation?

Back

Preview of the front of card 5
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