Food Production Flashcards
How are soil ions controlled?
Adding fertilisers to the soil or growing in a hydroponic culture
Why are soil ions controlled?
Extra mineral ions can be taken up and used to make proteins and other compounds for growth
How is soil structure controlled?
- Ploughing fields to break up compacted soil
- Adding manure to improve drainage and aeration of heavy clay
Why is soil structure controlled?
Good aeration and better drainage allows better uptake of mineral ions (by active transport) and water
How is soil pH controlled?
- Adding lime (calcium salts) to acidic soil
- Few soils are too alkaline
Why is soil pH controlled?
Soil pH can affect crop growth as an unsuitable pH reduced mineral ions uptake
How is carbon dioxide, light and heat controlled?
- These cannot be controlled for field crops but in a greenhouse or polytunnel all can be altered to maximise yield
- Burning fuels produces heat and CO2
Why are carbon dioxide, light and heat controlled?
All may limit photosynthesis and the production of the organic substances needed for growth
Why can greenhouses and polytunnels provide very controlled conditions?
- The transparent walls allow for enough natural light for photosynthesis during the summer months, whilst additional lighting can be used in winter
- Short wavelength IR entering is absorbed and re-radiated as longer wavelength IR which cannot escape so it causes heating (greenhouse effect). Also there are no convection currents that would cause cooling
- Can be heated
- If heaters use fossil fuels, the CO2 can be used for photosynthesis and the water vapour increases humidity therefore reducing transpiration
- Hydroponics can provide the perfect balance of mineral ions
What do fertilisers do?
Provide crops with extra nitrogen
What are the pros of pesticides?
- Kill pests
- Easy to apply
- Quick
What are the cons of pesticides?
- Bioaccumulation
- Resistance developed
- Costly
- Unspecific killing
- Soil contamination
- Biodiversity loss
What are the pros of biological control?
- Low toxicity
- Safer
- Sustainable
- No need for repeated application
- Specific
What are the cons of biological control?
- Slow
- Costly
- Can go badly wrong
What techniques are used to increase productivity in fish farming?
- The water quality can be measured for temperature, oxygen levels, water clarity and chlorophyll levels to warm of algal blooms
- Air can be pumped in to increase the amount of dissolved oxygen
- The water is filtered to remove fish waste
- The diet is controlled in quality and frequency
- Enclosing fish protects them against predators
- Pesticides can be used to kill off parasites
- Fish are often sectioned by size to reduce intraspecific predation
- Selective breeding can be used to improve the quality of the fish
What is the alcoholic component of beer?
Ethanol produced during the fermentation of yeast
How is fermentation used in bread making?
The carbon dioxide produced causes the bread to rise and the alcohol gives the bread its flavour as it is fermented in the baking process
How to investigate the rate of anaerobic respiration in yeast
- A small amount of water is gently boiled in a boiling tube to remove any dissolved air
- The water is allowed to cool before dissolving some sugar and adding yeast
- Then it is stirred and a thin layer of paraffin added on top to prevent any oxygen from diffusing in
- Set up a control apparatus using boiled yeast
- They are left in a warm place for an hour or two
- If bubbled through limewater, the gas will turn it cloudy. if passed through hydrogen carbonate indicator, the time taken for colour change can be recorded and compared to the control
How is yogurt made?
Lactobacillus bulgaricus is a bacterium which converts lactose into lactic acid. The acid denatures the milk protein causing it to coagulate (become semi-solid). It also makes the milk taste sour and prevents other microbes from growing in the yogurt
What is the method to investigate yogurt production?
- Add 1.5 teaspoons of powdered skimmed milk to 125cm3 of whole milk
- Using a Bunsen burner, tripod and gauze, heat the milk over a medium blue flame, stirring until it reaches 80oc to pasteurise it
- Let it cool to 46-69oc using a thermometer cleaned with antiseptic wipe
- Divide the mixture between 2 beakers and add 1/2 teaspoons of live yogurt to one and 1/2 teaspoons of sterile yogurt to the other
- Stir both mixtures well then cover them with aluminium foil and incubate at 40oc for 9-15 hours
Why must the culture be pure and all nutrients and equipment sterilised in industrial fermenters?
To avoid competition for expensive nutrients and limit the danger of disease-causing microorganisms contaminating the product
What does the inlet do?
Provides the organisms that respire aerobically with sterile air
What does the nutrient input do?
Provides the microorganisms with energy source and growth materials that they require
What do the paddle stirrers do?
Continuously mix the contents of the bioreactor to ensure that nutrients and heat are dispersed evenly
What does the microbe input do?
The organisms are cultured separately until they are growing well
What does the gas outlet do?
Ensures that the pressure does not build up during the process. Gas can be collected and sold to fizzy drinks companies as a lucrative by-product
What does the constant temperature water jacket do?
Ensures that the temperature remains constant to promote optimal enzyme activity and prevent denaturing
What does the computer do?
Analyses information from the probes and adjusts settings and inputs to maintain optimum conditions
What do the probes do?
Continuously detect the internal conditions including pH, temperature and oxygen levels
What happens after the final product is removed?
It is sent for purification and final processing
