harnessing biology 5.10, 5.11, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9B, 4.3B, 4.4B, 4.18B, 4.12, 4.16, 4.17 Flashcards
how to selectively breed:
- choose individuals with the desired feature
- let only these individuals reproduce
- choose the offspring that have the desired feature
- let only these individuals reproduce
- repeat steps 3 and 4 until you have produced a variety in which all the individuals show the desired feature
selective breeding:
produces different varieties however they are still the same species
what is the key to success when selectively breeding?
not allowing individuals with undesirable features to breed
how do farmers try and make a profit from their farms?
try and control the environment in a way to maximise the yield from crop plants and livestock
ways inside areas (greenhouses) can control factors chosen to grow crops:
- artificial heating
- artificial lighting
- additional carbon dioxide in the air
- regular watering
how do greenhouses and polythene tunnels provide enhanced conditions?
- transparent material allowing sufficient natural light for photosynthesis
- greenhouse effect raises temperature in the glasshouse
- burning fissile fuels or wood raises the temperature when the external temperature is too low, produces carbon dioxide and water vapour
- water vapour maintains a moist atmosphere so reduces water loss by transpiration
ALL INCREASING RATE OF PHOTOSYNTHESIS and increasing yield, by finding optimum conditions
what do fertilisers provide?
elements needed for plants to grow such as nitrates for proteins and magnesium for the production of chlorophyll
what are the two types of fertilisers?
organic
inorganic
what is an organic fertiliser?
made from the faeces of a range of animals, sometimes mixed with straw also compost from legumes such as clover
what is an inorganic fertiliser?
inorganic compounds carefully formulated to yield a specific concentration of a particular ion when applied according to the manufacture instructions
what are some advantages of organic fertilisers?
- improves soil structure
- greater range of minerals
- releases minerals over a longer period of time
- less cost to farmer, already available on the farm
what are some disadvantages of using organic fertiliser?
slow acting - had to be decomposed first
bulkier so more difficult than inorganic fertilisers to apply
may contain pests
what are some advantages of inorganic fertilisers?
mineral ions release immediately so fast acting
contents know
easy to apply
what are so disadvantages of inorganic fertilisers?
can lead to eutrophication as fertiliser is soluble
requires regular reapplication
how else can you replace lost nitrates?
nitrogen fixing plants :
grow a legume crop like clover in a field, they have nitrogen fixing bacteria in nodules on their roots, they convert nitrogen gas in air into ammonium ions
some of this is passed to the plants which use it to make proteins, when the crop is ploughed the protein and bacteria is broken down (decomposed) ammonium is released into soil
ammonium is converted to nitrate by nitrifying bacteria
what are pests?
they are organisms that reduce the yield of crop plants or stock animals
causing economic damage
how can pests be controlled?
chemical called pesticides
use another organism to reduce the number of pests - biological control
what are pesticides?
used to kill specific pests and improve the yield from the crops and livestock
can damage the ecosystem as often the pesticide molecules are simply passed higher up the food chain and become concentrated in the tissues of top carnivores
examples of types of pesticides:
herbicides : kill plant pests
insecticide : kill insects
fungicides : kill fungi
molluscicides : kill molluscs
how does biological control of pests work?
uses predator species rather than a toxic chemical so reduce the number of pests
what is the slight downside to biological control?
it never eradicates a pest as if the organism killed off all the pests then it would die from lack of food so the aim is to reduce pest numbers
what’s the effect of introducing a natural predator?
ladybirds can be used to control the population of aphids in orange groves
what’s the effect of introducing a herbivore?
eats pest plants such a prickly pear cactus in australia
what’s the effect of introducing a parasite?
wasp encarsia lays its eggs in whitefly eggs and reduces the population