Agriculture Flashcards
Define ‘Pasture’
An area of land used for grazing livestock
Define ‘Sustainable’
An activity that can be carried out without making life more difficult for people in the future
Define ‘Photoautotroph’
An organism that produces high-energy food substances using light (e.g. all photosynthetic organisms)
Define ‘Food chain’
A sequence of organisms to show their feeding relationships and food energy flow
Define ‘Trophic level’
A position in a food chain (e.g. primary producer)
Define ‘Autotroph’
Organisms that build up high-energy molecules using a source of energy. They do not rely on other organisms (they are self feeders e.g. plants)
Define ‘Heterotroph’
Organisms that can’t produce their own high-energy molecules; they must gain their energy from other living organisms
Define ‘Herbivore’, ‘Carnivore’ and ‘Omnivore’
Herbivores get their energy from plants
Carnivores get their energy from animals
Omnivores get their energy from both
Ruminants are herbivores. They have a large complex stomach. The largest stomach chamber is called the ‘rumen’. Outline the ‘rumen’
In here there are symbiotic bacteria that produce the enzyme cellulase which allows the digestion of cellulose (other heterotrophs such as humans cannot utilise cellulose)
Give an example of an omnivore
Pig 🐷
What 3 groups can heterotrophs be divided into?
Herbivores
Carnivores
Omnivores
Name the 5 factors that affect the selection of food species
Environmental
Social
Religious
Ethical
Technological
Species can be controlled to increase their suitability for cultivation, yield and saleability. How?
The use of hormones and antibiotics to control growth
An increase in the desirable features of the food (e.g. growth/nutrition/taste) by genetic manipulation
Name the two types of genetic manipulation
Selective breeding
Genetic modification
Define ‘Genetic Modification’
Altering an organism’s genetic make-up by artificially introducing genes from another organism, often of another species
Define ‘Biota’
Living organisms
Define ‘Limiting Factor’
If the presence or absence of an environmental factor limits a process such as growth, it is a limiting factor (e.g. a nutrient being the limiting factor for plant growth)
Name 6 abiotic limiting factors that can be controlled
Nutrient supply Water supply Temp Light Acidity Carbon dioxide
Name 3 biotic limiting factors that be controlled
Population
The reduction of competition with other species by pest and disease control
Increasing the populations of desirable species such as soil biota and pollinating insects
Define solar insolation
Sunlight landing on a surface
Give two ways in which water might affect crops
Humid conditions can increase fungal diseases (e.g. of soft fruit)
Irregular water supplies can cause some fruit to expand and split
What is the temperature most plants need to grow?
Temperatures above 5 Celsius
Grass stops growing at temps below this, so dairy cattle that are pasture-fed must be kept in warmer of areas of the U.K. such as South-West England
Define ‘Lodging’
Where (cereal) crops are flattened by strong winds
What might solar insolation be affected by?
Latitude
Cloud cover
Seasonal and daily changes
Define ‘Latitude’
The angular distance of a place, expressed in degrees and minutes
Ploughing is difficult on gradients over 10 ° . Why is this?
Ploughing tractors can not operate on very steep slopes
Define ‘Topography’
The 3D shape of the land surface
Define ‘Aspect’
The direction something faces in terms of sunlight
Tsetse flies in Africa carry the disease ‘sleeping sickness’; who is this a problem for?
Cattle
Why might religion affect the selection of species for cultivation?
Some religions have dietary requirements (e.g. Hindus do not eat cattle)
Define ‘Tenant Farmer’
A farmer that rents their land; they may have less incentive to invest in their farms to improve the production system used
Name 3 political factors that might affect the selection of species for cultivation
State control
Financial support/subsidies
Quotas
Outline ‘state control’ as a political factor that might affect the selection of species for cultivation
In a few cases governments have had complete control of commercial agriculture and have controlled what is grown
Outline ‘financial support/subsidies’ as a political factor that might affect the selection of species for cultivation
The importance of food production often leads governments to provide support to agriculture, which might involve financial help or tax reductions
Outline ‘quotas’ as a political factor that might affect the selection of species for cultivation
Governments sometimes use quotas to limit production and prevent overproduction (e.g. milk quotas in the UK)
Define ‘Quota’
A limit on the number of items
Name 2 economic factors that may affect the selection of species for cultivation
Market demand
Labour supply
Outline ‘labour supply’ as an economic factor that might affect the selection of species for cultivation
Low farm wages make it difficult to get enough workers for labour-intensive methods such as soft fruit production
Name 6 technological factors that may affect the selection of species for cultivation
Transport infrastructure Mechanisation Fertilisers Irrigation Fuel supplies Seeds and livestock
Outline ‘fertilisers’ as a technological factor that might affect the selection of species for cultivation
Until the 1900s nitrates were mined in South America. The development of the Haber process allowed the manufacture of synthetic nitrate fertilisers and their more widespread use
Define ‘Haber process’
A chemical process used to manufacture ammonia from which nitrate fertilisers can be made
Outline ‘fuel supplies’ as a technological factor that might affect the selection of species for cultivation
Energy intensive production systems are only possible where such inputs are readily available (e.g. MEDCs)
What 3 methods are there of asexual reproduction?
Vegetative propagation
Micropropagation
Cloning
Define vegetative propagation
Natural asexual reproduction
Some plants, such as the strawberry, naturally reproduce asexually (although the strawberry plant also reproduces sexually)
Outline micropropagation
Involves growing plants from small pieces of plant tissue on a sterile nutrient medium such as agar jelly which contains sugars and mineral nutrients
Outline ‘Cloning’
Involves taking genetic material from the body cell of one individual and implanting it into the egg cell from
a different individual so it develops like a normal fertilised egg
Name 3 methods of animal breeding
Selective breeding
Artificial insemination
Embryo transfer
Define ‘Breed’ (in terms of a breed of animal)
A group of animals or plants within a species that have a distinctive appearance or characteristics
Define ‘Hybrid vigour’
The good health achieved by the breeding between breeds that are not closely related (cross breeding)
Give two reasons why cross breeding (often used within selective breeding) is good
Can be used to combine desirable characteristics in a hybrid breed
Reduces problems of homozygous recessive genes found in inbred varieties
Outline ‘Artificial insemination’
Allows the semen from one male to be used to impregnate many females
Sperm is collected and frozen and then used when needed
By artificial insemination, how many calves can a bull produce each year?
10,000 calves
Outline ‘Embryo transfer’
Enables a female to be the mother of more offspring then she could naturally produce
E.g. a pedigree cow given an injection of a hormone to stimulate ovulation and he release of eggs which are washed out of her uterus and can be fertilised using the semen of a pedigree bull
What is IR8?
A green revolution rice variety
What is the ‘Green Revolution’?
The agricultural changes since the mid 20th century, where high yielding cereal varieties were bred to increase food production
Genetic engineering can be used in plants as well as animals. Give two examples of GM crops
‘Roundup-ready’ soya beans which are resistant to the herbicide ‘roundup’ which can be used to kill weeds without killing the crop
BT corn- the bacterium BACILLUS THURINGIENSIS produces a toxin that kills insects. The gene had been transferred to corn
What is golden rice?
Golden rice includes genes from a daffodil and a soil bacterium which produce beta-carotene. This forms vitamin A when the rice is eaten (so this rice can tackle vitamin A deficiency in many tropical countries where rice is a staple food)
Give 3 disadvantages of GM crops
Some claims that people eating GM foods suffer allergies
‘Horizontal gene transfer’ may occur where bacteria and viruses combine the inserted gene into their own genetic material and gain new characteristics
Pollen from GM crops may be transferred to organic crops which could invalidate their organic status
Name 3 advantages of GM crops
Allow desirable genes to be introduced from other species which could never be achieved by selective breeding within the crop species itself
If GM crops are pest-resistant then pesticide use may be unnecessary, so reduces environmental damage
Define ‘Auxin’
A group of plant hormones
Define ‘Gibberelin’
A group of plant hormones
What do gibberelins do?
Inhibit shoot growth - used on cereals to produce shorter stems
They stimulate seed germination
They inhibit root growth so more energy goes into fruit or seed growth
They increase fruit size and grape cluster size
Name two types of animal hormone used for growth control
BST (bovine somatotropin)
Anabolic steroid hormones
Define ‘BST’
Bovine somatotropin- an animal hormone used to stimulate milk production
Define ‘Anabolic steroid hormones’
A female or male hormone used to increase livestock goss growth efficiency
What is growth rate?
A measure of the increase in body mass per unit time
What is gross growth efficiency? (GCE)
A measure of the efficiency with which food eaten by livestock is converted into body mass
By how much can anabolic steroid hormones increase GGE?
Up to 10%
What are ‘Endemic pests’?
Always present, usually in small numbers
What are ‘Epidemic pests’?
Not normally present but there may be ‘outbreaks’ and become a problem when the population suddenly increases
Ethene is a plant growth hormone. What does it do?
Stimulates the ripening of fruit such as bananas
Why might intensive rearing make it easier for pests and diseases to spread rapidly?
It involves keeping large numbers of animals close together
Name the 5 pesticide application methods
Spraying of crops
Powder coating of seeds
Soil injection to kill pests in soil
Dipping of livestock to kill skin parasites
Drenching where livestock drink the pesticides to kill internal parasites
Name the 5 properties of pesticides
Specificity
Persistence
Toxicity
Bioaccumulation/magnification
Mode of action
Outline ‘Specificity’ as a pesticide property
Some pesticides = ‘broad spectrum’ and kill a wide range of species
Other pesticides = ‘narrow spectrum’ and kill a smaller range of species as they are more specific
Outline ‘Mode of action’ as a property of pesticides
Surface acting pesticides are sprayed on the crop
Systemic pesticides are absorbed then translocated through the plant
What are the two main types of herbicides?
Hormone herbicides - these are systemic and kill weeds by modifying some aspect of growth
Contact herbicides
Give an example of a hormone herbicide and how it works
2, 4 D - kills broad-leaf weeds by causing excessive cell elongation
What are the 3 types of insecticides?
Organochlorines
Organophosphates
Pyrethroids
Outline ‘organochlorines’
Very toxic to insects
Low toxicity to mammals
Are liposoluble and persistent so can build up along food chains
An example is DDT
Outline ‘organophosphates’
Less persistent than organochlorines and do not build up along food chains
Are very toxic to mammals including humans
Ah example is parathion
Outline ‘pyrethroids’
More toxic to insects
Easily degraded when exposed to UV
Low mammal toxicity but are toxic to fish
Define ‘Zoonose’
A micro-organism that is carried by livestock which, if transferred to humans, causes disease
Why are livestock given antibiotics? 3 reasons
To control infections in sick animals
To prevent infections occurring
To increase the gross growth efficiency of the livestock by reducing the population of gut bacteria
What are 2 problems with antibiotics?
If an antibiotic does not kill all the bacteria then the most resistant ones will survive
Bacteria can exchange genetic information, so antibiotic resistance that develops in a harmless species could be transferred to a human pathogen
Name 5 methods of pest control that DO NOT use pesticides
Mulching
Sterile-male techniques
Biological control
Pheromone traps
Crop rotation
Outline ‘Mulching’ as a method of pest control
A layer of material e.g. shredded bark which can inhibit weed growth
Outline ‘Pheromone traps’ as a method of pest control
Many insects attract a mate by releasing a scent (pheromone). If the scent is made artificially then it can be used to trap one sex which will prevent successful breeding
Outline ‘Sterile-male techniques’ as a method of pest control
The females of some insect species only mate once. If a female mates with a sterile male then she will never produce any offspring
Name an example of biological pest control
Parasitic wasps are used to control pests such as whitefly in greenhouses
Integrated pest control attempts to control pests by using a range of methods. Outline the main principles
Cultural techniques to make environment less beneficial for pests
Cultivating species less likely to suffer pest attack
Appropriate non-pesticide techniques
Use of pesticides when essential- specific and non-persistent
‘Temperature’ is a limiting factor which may limit agricultural productivity. How might it be controlled?
Artificial heating of greenhouses used to extend growing season
Heating livestock animal houses reduces the amount of food energy they use to keep warm, increasing growth
‘Carbon dioxide’ is a limiting factor which may limit agricultural productivity. How might it be controlled?
Can be increased in enclosed places such as greenhouses by burning fuels such as paraffin
Maintaining a high humus content in soil helps to do what?
Retain water
What might too much water lead to?
Can lead to the soil becoming anaerobic. This encourages denitrifying bacteria rather than aerobic nitrifying bacteria so soil nitrate levels will be low
Name 2 macronutrients (a plant nutrient needed in large amounts)
Nitrogen
Phosphorus
Outline ‘Nitrogen fixation’
Leguminous plants have root nodule bacteria such as ‘rhizobium’, which fix nitrogen that can be used by the growing crop
Name 2 advantages of natural fertilisers
Cheap as they are waste products (e.g. manure)
Increase humus content so reduces erosion risk
Name 2 disadvantages of natural fertilisers
Usually bulky so difficult to transport and apply
Application will not provide large amounts of nutrients quickly as slow release
Name 2 advantages of artificial fertilisers
Available for crop use as soon as they are applied
Mechanical application is easy
Name 2 disadvantages of artificial fertilisers
Do not add humus to the soil
Expensive to manufacture as a lot of energy is required
Soil can be made less acidic by the addition of what?
Lime
What is ‘Intensive agriculture’?
Farming where high yields are achieved by using large inputs per unit area
What is ‘Extensive agriculture’?
Farming where the maximum total yield is achieved by distributing inputs over the total available area. Inputs are usually low
What crop may be used to conserve nutrients?
Green manure
