Agriculture - Chapter 13 Flashcards
Abiotic Factors
Physical factors such as light, temperature and water.
Agroecosystem
The living organisms, physical processes and their interactions in a farming system. (OR a modified natural ecosystem to optimize the production of human food).
Anabolic Steroid Hormone
A female or male hormone used to increase livestock gross growth efficiency.
Artificial Insemination
A form of selective breeding where semen is collected from a chosen male and is inserted artificially into the chosen female to cause her to become pregnant.
Asexual Reproduction
Production of new organisms using the genetic material from a single individual. The offspring are genetically identical to the parent.
Aspect
The direction something faces in terms of sunlight.
Autotroph
An organism that can capture light or chemical energy from the environment to make high-energy substances such as carbohydrates. They include photoautotrophs and chemoautotrophs.
Auxins
A group of plant hormones.
Bioaccumulation
The increase in concentration of a substance in living tissue.
Biomagnification
The progressive bioaccumulation of a material along a food chain.
Biota
Living organisms.
Biotic Factors
Biological factors such as food and disease.
BST
Bovine somatotropin - an animal hormone used to stimulate milk production.
Carnivore
An organism that gains its food energy from heterotrophs.
Carrying Capacity
The greatest population that can be supported sustainably in an area.
Cellulase
An enzyme that digests cellulose that is produced by some bacteria, fungi and protozoans.
Cellulose
The carbohydrate made of linked glucose molecules, which is a major component of plant cell walls and wood.
Chemoautotroph
An organism that gains its metabolic energy using energy from chemical reactions, e.g. nitrifying bacteria in the nitrogen cycle.
Cloning
An artificial form of asexual reproduction.
Countryside Stewardship Scheme
A scheme where farmers could get grants for a range of activities that benefited the environment or improved amenity value for the public.
Crop Rotation
The practice of growing a different crop in a field on a cycle of three, four or five years.
Crossbreeding
Producing offspring, by mating of two different breeds or variety.
CSS
Countryside Stewardship Scheme.
Edaphic
A factor related to soil, particularly as it affects living organisms.
Endemic Pest
A pest that is normally present.
Environmental Stewardship Scheme
An agri-environmental scheme where farmers receive payments for farm management practices that benefit wildlife and the environment. Higher payments available to organic farms.
Environmentally Sensitive Area
Farmers in areas of ESA could opt into a scheme where they would be paid for continuing with their traditional farming techniques.
Epidemic Pest
A pest that is not normally a problem but may become a serious pest when the population suddenly increases.
ESA
Environmentally Sensitive Areas.
ESS
Environmental Stewardship Scheme
Ethylene
Chemical that stimulates fruit ripening.
Eutrophication
The natural nutrient enrichment of a water body. It can be accelerated by human actions such as the release of sewage effluent or the use of fertilisers that are leached into water bodies.
Evapotranspiration
The combined movement of water into the atmosphere from the evaporation from surfaces and transpiration from leaves.
Extensive Agriculture
Agriculture where the maximum total yield is achieved by distributing the inputs over the total available area. Inputs are usually low.
F1 Hybrid
The first generation of offspring produced by breeding from two distinct true-breeding varieties. All the offspring have the same combinations of characteristics.
Food Chain
A sequence of organisms arranged to show their feeding relationships and food energy flow:primary producer, primary consumer, secondary consumer, tertiary consumer.
Gene Pool
The total variety of different genes in all the members of a population.
Genetic Engineering
The method of altering an organisms genetic makeup by artificially introducing genes from another organism, often of another species.
Genetic Modification (GM)
The method of altering an organism’s genetic makeup by artificially introducing genes from another organism, often of another species.
Gibberelins
A group of plant hormones.
GM
Genetic Modification
Haber Process
A chemical process used to manufacture ammonia from which nitrate fertilisers can be made.
Herbivore
An animal that only eats plant food.
Heterosis
The hybrid vigour produced by breeding two organisms that are not closely related.
Heterotroph
An organisms that gains its organic compounds for energy and growth from other organisms.
Horizontal Gene Transfer
The transfer of genetic material between organisms without normal breeding taking place, e.g. the transfer of genes that give pesticide or antibiotic resistance between bacteria.
Humus
The colloidal material in soil that is the end product of the decomposition of dead organic matter.
Hybrid
The offspring of two plants or animals of different species or varieties, such as a mule.
Hybrid Vigour
The good health achieved by breeding between breeds that are not closely related. This reduces the risk of inbreeding and recessive gene diseases.
Inbreeding
Describes breeding between closely related individuals. Inbreeding increases the risk of recessive genes producing offspring with disadvantageous characteristics.
Insolation
Exposure to the suns rays.
Intensive Agriculture
Farming where high yields are achieved by using large inputs per unit area.
IR8
A Green Revolution (Agricultural changes since mid 20th century where high yielding cereal varieties were bred to increase food production) rice variety.
Leachate
Liquids and dissolved materials such as fertilisers washed through the ground, usually downwards.
Limiting Factor
An environmental factor present in insufficient amounts to allow a process to occur at a faster rate, e.g. a nutrient being the limiting factor for plant growth.
Liposoluble
The property of a substance dissolving in lipids.
Macronutrient
A plant nutrient needed in large amounts, e.g. N, P, K.
Marshall Plan
A US scheme after the Second World War to provide aid to Europe.
Micronutrient
A plant nutrient needed in small amounts.
Micropropagation
A tissue culture method where large numbers of plants can be produced from a tissue sample from and original plant, without the need for seeds. The young plants may be raised on agar under sterile conditions.
Monoculture
The growth of a single type of crop, usually over a large area.
Mulch
Material added to the soil surface, e.g. shredded crop waste to inhibit weed growth.
Omnivore
An organism that eats plant and and animal foods.
Organochlorine Pesticide
Persistent insecticide group, e.g. DDT, dieldrin, aldrin. Most are now banned or restricted.
Organophosphate Pesticide
Insecticide group, e.g. parathion, malathion.
Pasture
An area of land used for grazing livestock.
Ped
The basic unit of soil structure where particles of sand, silt, clay and humus form aggregates.
Persistence
A measure of the rate at which a material breaks down and therefore the length of time it remains in the environment.
Pesticide
A chemical that is used to kill pest species.
Pheromone
A chemical released by an organism that changes the behaviour of other members of the same species, especially to attract a mate.
Photoautotroph
An organism that produces high-energy food substances using light, e.g. all photosynthetic organisms.
Pyrethroid Pesticide
Insecticide group.
Quota
A limit on the number or quantity of items, e.g.. milk production.
Rumen
The stomach chamber in which bacteria digest cellulose in ruminants, e.g. cattle , sheep and other large herbivores.
Selective Breeding
Producing offspring from particular chosen parents, usually to produce offspring with desirable characteristics.
Set Aside Land
Farmland that has been taken out of production and is not cultivated but is kept in a condition where it could be farmed again.
Specificity
A measure of the differing toxicities of a substance on different organism. A specific substance is very toxic to some organisms and much less toxic to others.
Sustainable
An activity that can be carried out without making life more difficult for people in the future.
Systemic
A substance that is absorbed and transported throughout an organism.
Tenant Farmer
A farmer that rents land from the owner.
Tillage
Cultivation by turning the soil, e.g. ploughing.
Topography
The 3D shape of the land surface.
Toxicity
A measure of how poisonous a substance is, usually caused by enzyme inhibition.
Transgenics
The process of artificially transferring genetic material from one organism into an individual of another species.
Transpiration
The loss of water by evaporation from the stomata of leaves.
Trophic Level
A position in a food chain, e.g. primary/secondary producer.
True-Breeding Variety
A variety of selectively bred organisms where all members are genetically almost identical and produce similar offspring.
Tuber
A much thickened underground part of a stem or rhizome, e.g. in the potato, serving as a food reserve and bearing buds from which new plants arise.
USLE
Universal soil loss equation.
Vegetative Propagation
Asexual reproduction
Zoonose
A micro-organism that is carried by livestock which, if transferred to humans, causes disease.
Gross Primary Productivity
The amount of energy fixed in photosynthesis.
Assimilation
The chemicals become part of the animal’s cells.
What are the advantages of Asexual Reproduction?
- The survival of young plants is high as water and nutrients are provided by the parent plant to sustain the young through a time when survival may be difficult.
- The plants are all genetically identical and have the same characteristics e.g. taste, growth rate, disease resistance etc.
What are the disadvantages of Asexual Reproduction?
- Due to the offspring being genetically identical to the parents, there is no opportunity to improve their genetic qualities.
- Asexual reproduction usually produces smaller numbers of offspring than sexual reproduction.
What are the 2 methods of artificial asexual reproduction?
- Cuttings.
- Micro-propagation.
What is the difference between cuttings and micro propagation?
Cuttings - putting the cut end of a stem into damp soil. Roots develop from the cut end and a new plant is produced.
Micro-Propagation - Growing plants from small pieces of plant tissue on a sterile nutrient medium under carefully controlled conditions.
Why is sexual reproduction essential for evolution?
It produces individuals with new and unique combinations of genetic materials.
What methods can be used to manipulate breeding in animals and increase its effectiveness/productivity?
- Artificial insemination.
- Embryo transfer.
What’s the difference between AI and Embryo transfer?
AI- allows males to father many offspring.
Embryo transfer - Allows a female to be the mother of many more offspring than she could naturally produce.
What are some examples of selectively bred plants crops?
- Disease-resistant potatoes.
- Disease resistant wheat.
- IR8 rice.
What are some examples of selectively bred animals?
- Belgian blue cow.
- Featherless chickens.
- Meidam pig.
- Romney sheep.
What an example of an genetically engineered plant?
-Golden rice with a gene from daffodils and a soil bacteria which causes the rice to form vitamin A.
What are the advantages of Genetically Modified crops?
- It allow certain characteristic to be introduced without the time needed for normal selective breeding to introduce it.
- They allow desirable genes to be introduced from other species (e.g. golden rice).
- They can create pest-resistant crops which removes the need for pesticides which will reduce the environmental damage caused by killing non-target species.
- Edible vaccines and reduces hunger and malnutrition in LEDCs.
- Less wastage as desired product achieved immediately.
What are the disadvantages of Genetically modified crops?
- There are some claims that GM foods can cause food-related allergies.
- ‘Horizontal Gene Transfer’ may occur where bacteria may combine the inserted gene into their own genetic material, contributing to antibiotic resistance.
- Pollen from GM crops may be transferred to organic crops and this could invalidate their organic status and give rise to ‘super-weeds’.
- LEDC’s may not be able to afford GM seeds.
What are the issues that must be considered by environmentalists studying agriculture?
- The impact of agriculture on the biosphere.
- Use of other environmental resources in agriculture.
- Pollution caused by agriculture.
- Development.
- Food for human survival.
Why is the potential for cultivating new areas limited?
Much of the remaining land is too dry, wet, cold, hot, steep, covered in ice or has no soil.
Why do autotrophs have a big advantage for survival?
Because they don’t rely on other organisms for their energy supplies.
What factors affect the choice of species to be farmed?
- Environment.
- Social.
- Ethical.
- Technological.
- Economic.
In what ways can plant species be controlled to increase their suitability for cultivation, yield and saleability?
- The use of chemicals (E.g. hormones and antibiotics) to control growth.
- An increase in the desirable features of the food by genetic manipulation: by selective breeding or genetic modification.
What are the abiotic limiting factors in an agroecosystem?
- Nutrient supply.
- Water supply.
- Temperature.
- Light.
- Acidity.
- Carbon Dioxide.
What are the biotic limiting factors in an agroecosystem?
- Population control.
- Competition with other species by pest and disease control.
- Increasing the populations of desirable species such as soil biota and pollinating insects.
How does water affect crops?
- Some crops need a lot of water e.g. rice.
- Wheat has low water requirements.
- Irregular water supplies can cause some fruit to expand and split.
- Humid conditions can increase fungal diseases.
What factors of the area affect the selection of species for cultivation?
- Water availability.
- Light intensity.
- Soils (Edaphic factors).
- Temperature.
- Altitude.
- Topography.
- Indigenous and introduced pests and diseases.
What are the different types of agro-ecosystems?
- Commercial (for a profit).
- Subsistence (for own benefit).
- Intensive (large inputs per unit area).
- Extensive (small inputs per unit area).
- Organic (non-chemical inputs).
- Inputs (Uses artificial chemical inputs).
Why do slopes on agricultural land make farming difficult?
Much farm machinery can’t operate on very steep slopes (difficult over 10 degrees). Rice padi fields for example must be flat in order to be flooded.
What are the main edaphic factors that affect soil fertility?
- Nutrient availability.
- Structure (ped type).
- Texture (particle sizes).
- Depth.
- pH.
- Biota.
What social factors will be taken into account when choosing what crops are grown?
- Cultural factors (E.g. horse meat not being eaten in the UK).
- Religious factors.
- Ethical issues (E.g. Demand for free-range/organic food has increased).
What economic factors will affect a farmers choice in crop?
- Market demand.
- Subsidies/incentives/grants.
- Labour supply.
- Labour costs.
- Capital availability and interest costs.
How has technological development enabled the cultivation of land more efficiently?
- Transport infrastructure (Long distance, rapid, bulk transport has become easier, its possible to produce foods in areas with no local demand).
- Mechanisation (machinery allows large scale ploughing, spreading of agrochemicals, harvesting better food processing, storage etc).
- Fertilisers.
- Irrigation.
- Fuel supplies.
- Seeds and livestock.
How can plant hormones be used to control aspects of plant growth and what are the main hormones used.
-They can delay fruit blossom until after frost.
-They increase sap flow in rubber trees.
-Produce seedless fruit.
3 main hormones are Auxins (controls growth of roots and shoots), Giberellins (they regulate growth and can interfere with developmental stages e.g. seed germination, development) and Ethylene (used to regulate ripening).
What are the 2 types of animal hormones and what disadvantages do they have?
-Steroid hormones (Increase gross growth efficiency of livestock and produces leaner less fatty meat).
-Non-steroid hormones (e.g. those that increase milk production in cattle).
They have possible health effects of the animal and may have health effects for the humans eating them.
In what ways do pests cause damage?
- Reduced harvest due to competition for water, light, nutrients etc.
- Kill the crop or livestock.
- Reduced quantity of harvest.
- Cause human disease.
What is the difference between an Endemic pest and an epidemic pest?
Endemic, they are always present, usually In small numbers.
Epidemic, not normally present but they have outbreaks where they rapidly become a major problem.
How can pests and disease be controlled?
- Biological pest control.
- Crop rotation to prevent disease build up.
- Synthetic pesticides.
Why can monocultures and intensive rearing lead to a more serious pest infestation?
- As pests are able to spread more easily throughout the whole area.
- Intensive rearing of livestock makes it easier for disease to spread as they’re more densely stocked.
What properties do pesticides show that make it a problem for the environment?
- Specificity.
- Persistence.
- Toxicity.
- Bio-accumulation/Bio-magnification.
- Mode of action (E.g. Systemic).
How do weeds reduce crop yields/
- Competing for nutrients, water, light etc.
- Contaminating the harvested crop and spoiling the taste.
- Providing the food for other pests, e.g. insects and fungi.
What are the two main types of herbicides and how do they work?
- Hormone herbicides (kill weeds by modifying some aspect of growth or development in a way that’s harmful to the plant).
- Contact herbicides (‘scorch’ the leaves on contact).
How do insects cause damage?
- They reduce harvests by eating the crop.
- They spoil the appearance of the crop.
- They disease such as sleeping sickness of cattle.
What are the 3 types of insecticide and what are some examples of each?
- Organochlorines (DDT- toxic to insects but have low toxicity to animals).
- Organophosphates (Malathion, Parathion- very toxic to mammals).
- Pyrethroids (Pyrethrin - low mammal toxicity).
Why are livestock given antibiotics?
- To control infections in sick animals.
- To prevent infections occurring.
- To increase the gross growth efficiency of the livestock by reducing to population of gut bacteria.
What are the problems caused by antibiotics?
If the antibiotic doesn’t kill all the bacteria then the most resistant ones will survive. Some are human pathogens and these are called zoonoses. If they’re transferred to humans, they may cause infections that are difficult to treat and some antibiotics may be ineffective or much higher doses may be required.
How can antibiotic resistance be transferred from harmless species be transferred to a human pathogen?
Antibiotic resistance can develop in harmless species due to the high levels of antibiotic being used but bacteria can exchange genetic information between species.
How can pests be controlled without pesticides?
- Crop rotation, each epst species population will have declined to a low level before the crop that it harms will become avaliable again.
- Mulching, makes it difficult for weed seedlings to survive.
- Barrier crops, some plants repel pests (E.g. onions mask carrots smell protecting them from carrot root fly).
- Sowing density, being overcrowded may make them more susceptible to pests and diseases.
- Biological pest control.
- Disease.
- Sterile-male techniques.
What are some examples of biological pest control?
- Rice brown plant hopper, pesticide use stopped.
- Creation of predator habitats.
- Introducing species, E.g. new world screw fly controlled by male sterile techniques.
What other organisms on a farm may be beneficial species in incresing productivity?
- Pollinators.
- Nutrient cycling by nitrifying bacteria.
- Soil aeration by worms.
- Pest control, E.g. predatory birds.
Why is energy lost through each trophic level in a food chain?
It’s used by these organisms, releases in respiration as energy.
What abiotic environmental factors may limit agricultural productivity?
- Temperature.
- Light.
- Carbon Dioxide.
- Water (Too much or too little).
- Nutrient supplies.
How can temperature be controlled?
- Artificial heating of greenhouses can be used to extend growing season and allow the growth of out of season crops.
- Heating livestock animal houses reduces the amount of food energy they use to keep warm.
How can light be controlled?
Artificial light can be used to increase day-length and light intensity to control growth. It can allow plants to photosynthesis for longer or it can be used to stimulate laying.
How can water be controlled?
- Maintaining a high humus content helps retain water.
- Minimising heavy machinery reduces soil compaction.
- Extra water can be added by irrigation.
- Drip irrigation reduces the water lost by evaporation.
- If there is too much water, drainage rates can be increased by deep ploughing, digging drainage ditches or by laying perforated pipes in the soil.
How can nutrient supplies be controlled?
Nutrients are removed when the crops or livestock are removed so artificial ones need to be added if levels drop to a level where deficiency symptoms may appear. This is only usually needed by macronutrients.
- Cultural methods, how they’re grown.
- Artificial fertilisers.
- Natural fertilisers.
What are the cultural methods of managing nutrient supplies?
- Nitrogen fixation, Leguminous plants have root nodule bacteria such as Rhizobium, which fix nitrogen that can be used by the growing crop (Aerobic soils best).
- Crop rotation, growing a range of different crops over a sequence of years reduces the chance that any particular nutrient will be depleted to the point that plant growth is reduced.
How can pH be controlled?
Most plants grow best in slightly acidic soils as the nutrients are more soluble. Soil can be made less acidic by the addition of lime.
What is the difference between intensive and extensive agriculture?
- Extensive, inputs are spread over a large area of available land. Small inputs per unit area.
- Intensive, large inputs per unit area.
What are the environmental impacts of agriculture?
- Soil erosion.
- Monoculture.
- Pesticides.
- Methane from livestock.
- Loss of habitat.
- Water pollution.
- Deforestation.
- Less organic matter.
- CH4 from rice paddies.
- Eutrophication from NPK runoff.
- CO2 released from machinery.
- Energy exploitation for production of agro-chemicals.
- Effects of GM crops.
- Blue baby syndrome from nitrates.
- Drainage of wetlands.
- Water shortages due to demand for irrigation.
What pollution problems can the use of agrochemicals and energy cause?
- Fertilisers, some are mobile in the environment may be washed off the farmland into nearby water bodies which may cause eutrophication.
- Pesticides, often cause harm to non-target species.
- The release of methane.
- Energy use, most of the energy inputs come from fossil fuels and cause the same problems associated with any fossil fuel use.
What are the agricultural uses of energy?
- Machinery fuel e.g. for ploughing, irrigation etc.
- Agrochemical manufacture.
- Food processing.
- Food storage.
- Transport.
- Indirect uses e.g. manufacture of machinery etc.
In what ways can farming change the hydrological cycle?
- Evapotranspiration.
- Runoff and drainage.
- Irrigation.
In what ways does vegetation reduce soil erosion?
-Vegetation acts as a natural windbreak.
-Raindrop impact is reduced by vegetation cover and leaf litter.
-Soil organic matter binds soil particles together.
-Plant roots hold soil together.
Vegetation and organic matter increase the infiltration rate and reduce runoff.
How can farming cause accelerated soil erosion?
- Vegetation removal increases wind velocity at ground level.
- Loss of natural vegetation can increase raindrop impact.
- Ploughing loosens the soil so it can be washed or blown away more easily.
- Falling humus levels make the soil looser so it can be carried away more easily.
- Soil compaction by machinery can increase the rate of runoff.
- Overgrazing can reduce plant cover and root binding.
What are the environmental impacts of soil erosion?
- Shallower soils, reduces anchorage for plants.
- Loss of fertility.
- Sedimentation of rivers, increased turbidity, reduced velocity, decrease of river volume.
- Atmospheric particulates, reduced photosynthesis, increased human respiratory diseases.
- Desertification.
- Reduction in productivity of coral reefs due to sediments from deforestation.
What methods can be used to reduce the rate of soil erosion?
- Mulching.
- Cross-ploughing.
- Strip cropping.
- Avoid cultivating steep slopes.
- Terracing, creating ‘stepped areas’.
- Growing long term crops.
- Reduce stocking density, reduces poaching.
- Addition of organic matter.
- Zero-tillage farming.
What are the social impacts of agriculture?
- The uneven distribution of food.
- Misuse of the land.
What is the principles of the environmental stewardship scheme?
Farmers are subsidised for the methods they use that benefit the environment.
What are the principles of ESAs (Environmentally Sensitive Areas)?
Farmers in areas of landscape of ecological importance or ESAs can opt into a scheme where they would be paid to maintain wet grazing land for cattle and sheep rather than ploughing, draining the land or using pesticides.
What are the main principles of the CSS (Countryside stewardship scheme)?
Any farmer can apply for grants to manage their land in a way that would benefit the environment or provide facilities for public enjoyment.
Productivity.
Yield per unit area.
Green Manure.
A crop grown to conserve soil nutrients, rather than to produce food.
What are the principles of an agroecosystem?
- Factors which affect the selection of food species.
- Manipulation of the food species.
- Control of the environment.
What is an example of a barrier crop use?
Onions are used to protect carrots from root fly attack due to their strong smell.
What is an example of biological control?
The cactoblastis moth was introduced to Australia to control the prickly pear cactus.
What is an example of a companion crop?
Banana trees protect coffee bushes from extremes of tropical climate.
What is the difference between productivity and efficiency?
Productivity - Yield/unit area.
Efficiency - Yield/unit input.
