Food production (crops) Flashcards
How can glasshouses be used to improve crop yields?
In a glasshouse, environmental factors are able to be controlled to increase the rate of photosynthesis and therefore growth
Ways in which this is done include: artificial heating, artifical lighting, increased carbon dioxide concentration, increased watering
How can polythene tunnels be used to improve crop yields?
They are large plastic tunnels which cover crops
They protect crops from extreme temperatures, excessive wind and excessive rain
They also increase the temperature slighty and reduce the entry of pests
How can fertilisers be used to improve crop yields?
Plants need an array of mineral ions which they take up from the soil
Overtime, these will be depleted - therefore fertilisers are used to replace them to ensure crops are always receiving sufficient amounts of each mineral
They make crops grow bigger and faster, increasing yield
Fertilisers can be applied through spraying or spreading, and can be organic such as manure or compost or chemical
What are the reasons for pest control of crops?
Insects and other animals can eat crops
Weeds can compete with crops for nutrients and sunlight, limiting their growth
Fungi and bacteria can cause infections
All of this will reduce crop growth and therefore yield
What are the two types of pest control?
Chemical pesticides (insecticides, herbicides, fungicides etc.)
Biological control (purposeful introduction of other species)
What are the advantages and disadvantages of using chemical pesticides?
They are cheap, accessible and have an immediate effect
They kill the entire population of pests
However organisms can develop resistance to them
They can kill beneficial organisms such as bees
Bioaccumulation can occur and predators at the top of the food chain (including humans) can be harmed
What are the advantages and disadvantages of using biological control?
It is natural, long lasting, can target specific species, and only needs to be applied once
Organisms cannot develop a resistance to it
However they take longer to have an effect
They do not kill the entire pest population, only lower it
They may become a pest themselves, or eat other beneficial organisms
