Food Production Flashcards
Why do farmers use glasshouses and polythene tunnels?
Glasshouses and polythene tunnels provide an enclosed environment in which farmers can, to some extent, control the climate inside and increase their crop yields
What conditions can be manipulated in glasshouses?
- Artificial heating (enzymes controlling photosynthesis can work faster at slightly higher temperatures - only used in temperate countries such as the UK)
- Artificial lighting (plants can photosynthesise for longer)
- Increasing carbon dioxide content of the air inside (plants can photosynthesise quicker)
- Regular watering
Why are polythene tunnels useful?
- They can protect crops grown outside from the effects of the weather, including excessive wind, rain and extreme temperatures
- They also increase the temperature slightly inside the tunnel
- They can prevent the entry of pests that can damage plants or diseases that can kill plants
What are the 3 main factors that affect the rate of photosynthesis?
- Temperature
- Light intensity
- Carbon dioxide concentration
How does temperature affect the rate of photosynthesis?
- As temperature increases the rate of photosynthesis increases as the reaction is controlled by enzymes
- However, as the reaction is controlled by enzymes, this trend only continues up to a certain temperature beyond which the enzymes begin to denature and the rate of reaction decreases
How does light intensity affect the rate of photosynthesis?
- The more light a plant receives, the faster the rate of photosynthesis
- This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
How does carbon dioxide concentration affect the rate of photosynthesis?
- Carbon dioxide is one of the raw materials required for photosynthesis
- This means the more carbon dioxide that is present, the faster the reaction can occur
- This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
How do fertilisers help increase food supply?
Fertilisers increase the amount of key nutrients in the soil for crop plants, meaning that they can grow larger and are more healthy, which increases yields
How do pesticides help increase food supply?
These chemicals kill off unwanted insects and weed species, meaning that there is less damage done to crop plants by insects, as well as reducing competition from other plant species, which increases yields
What are the 2 types of fertilisers?
Organic fertilisers (manure and compost) and chemical fertilisers (dry granules or liquid form)
Why do plants need nitrogen?
- Absorbed in the form of nitrates
- Needed to make amino acids which are the building blocks of proteins
- Lack of nitrogen causes weak growth and yellowing of the leaves of plants
Why do plants need phosphorus?
- Absorbed in the form of phosphates
- Needed to make DNA and cell membranes
- Lack of phosphorus can cause poor root growth and discoloured leaves
Why do plants need potassium?
- Allows enzyme reactions to take place to produce ATP in respiration as well as being needed for the enzymes involved in photosynthesis
- Lack of potassium can cause poor growth of flowers and fruits, as well as brown spots on leaves
3 types of pesticide?
- Insecticides
- Herbicides
- Fungicides
Advantages of pesticides?
- Easily accessible and relatively cheap
- Have an immediate effect
- Kills the entire population of pests
Disadvantages of pesticides?
- Organisms they are meant to kill can develop resistance.
- They can often kill other beneficial organisms.
- They can be persistent chemicals - (they don’t break down in the bodies so can accumulate in great concentrations at the top of food chains)
- Need to be repeatedly applied