Food Production Flashcards
1
Q
Why do farmers use glasshouses and polythene tunnels?
A
Glasshouses and polythene tunnels provide an enclosed environment in which farmers can, to some extent, control the climate inside and increase their crop yields
2
Q
What conditions can be manipulated in glasshouses?
A
- 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
3
Q
Why are polythene tunnels useful?
A
- 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
4
Q
What are the 3 main factors that affect the rate of photosynthesis?
A
- Temperature
- Light intensity
- Carbon dioxide concentration
5
Q
How does temperature affect the rate of photosynthesis?
A
- 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
6
Q
How does light intensity affect the rate of photosynthesis?
A
- 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
7
Q
How does carbon dioxide concentration affect the rate of photosynthesis?
A
- 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
8
Q
How do fertilisers help increase food supply?
A
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
9
Q
How do pesticides help increase food supply?
A
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
10
Q
What are the 2 types of fertilisers?
A
Organic fertilisers (manure and compost) and chemical fertilisers (dry granules or liquid form)
11
Q
Why do plants need nitrogen?
A
- 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
12
Q
Why do plants need phosphorus?
A
- Absorbed in the form of phosphates
- Needed to make DNA and cell membranes
- Lack of phosphorus can cause poor root growth and discoloured leaves
13
Q
Why do plants need potassium?
A
- 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
14
Q
3 types of pesticide?
A
- Insecticides
- Herbicides
- Fungicides
15
Q
Advantages of pesticides?
A
- Easily accessible and relatively cheap
- Have an immediate effect
- Kills the entire population of pests
16
Q
Disadvantages of pesticides?
A
- 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
17
Q
What is biological control?
A
A species is introduced specifically to prey on the pest species – for example, parasitic wasps can control whitefly in glasshouse tomato crops
18
Q
Advantages of biological control?
A
- Natural method - no pollution.
- No resistance.
- Can target specific species.
- Long lasting.
- Does not need to be repeatedly applied.
19
Q
Disadvantages of biological control
A
- May eat other organisms instead of the pest.
- Takes a longer period of time to be effective.
- Cannot kill entire population.
- The organism used may not adapt to the new environment.
- May become a pest itself.
20
Q
What is yeast?
A
Yeast is a single-celled fungus that can carry out both aerobic and anaerobic respiration
21
Q
How is yeast used to make bread?
A
- When yeast carries out anaerobic respiration, it produces an ethanol and carbon dioxide
- Yeast will respire anaerobically if it has access to plenty of sugar, even if oxygen is available
- This is taken advantage of in bread making, where the yeast is mixed with flour and water
- The yeast produces enzymes that break down the starch in the flour, releasing sugars that can then be used by the yeast for anaerobic respiration
- The carbon dioxide produced by the yeast during anaerobic respiration is trapped in small air-pockets in the dough, causing the dough to rise (increase in volume)
- The dough is then baked in a hot oven to form bread
- During baking, any ethanol produced by the yeast is evaporated in the heat
- The yeast is killed by the high temperatures used during baking
- This ensures there is no further respiration by the yeast
- Once cooled, the bread is ready to be eaten
22
Q
Why are bacteria useful in food production?
A
- They are capable of producing complex molecules
- They reproduce rapidly,
23
Q
How is bacteria used to make yoghurt?
A
- Yoghurt is made in a process that relies on the presence of a specific type of bacterium – in this case, Lactobacillus
- First, all equipment is sterilised to kill other, unwanted bacteria and to prevent chemical contamination
- Milk is then pasteurised (heated) at 85-95°C to kill other, unwanted bacteria
- Contamination with other bacteria could slow production of the yoghurt by competing with the Lactobacillus for the lactose in the milk. It could also spoil the taste of the yoghurt
- The milk is then cooled to 40-45°C and Lactobacillus bacteria is added
- The mixture is incubated at this temperature for several hours, while the Lactobacillus bacteria digest milk proteins and ferment (digest) the sugar (i.e. the lactose) in the milk
- The Lactobacillus bacteria convert the lactose into lactic acid and this increased acidity sours and thickens the milk to form yoghurt.
- This lowering of the pH also helps to prevent the growth of other microorganisms that may be harmful, so acts as a preservative
- The yoghurt is then stirred and cooled to 5°C to halt the action of the Lactobacillus bacteria
24
Q
What are fermenter used for?
A
- Fermenters are containers used to grow microorganisms like bacteria and fungi in large amounts
- These can then be used for brewing beer, making yoghurt and mycoprotein and other processes not involving food, like producing genetically modified bacteria and moulds that produce antibiotics.
25
What is the main advantage of fermenters?
Conditions can be carefully controlled to produce large quantities of exactly the right type of microorganism.
26
How and why are fermenters cleaned?
- They are cleaned by steam to kill microorganisms and prevent chemical contamination.
- Therefore only the desired microorganisms will grow.
27
Why are nutrients controlled in fermenters?
Nutrients are needed for use in respiration to release energy for growth and to ensure the microorganisms are able to reproduce.
28
How and why is temperature controlled in fermenters?
- Temperature is monitored using probes and maintained using the water jacket.
- Ensures an optimum environment for enzymes.
29
How and why is pH controlled in fermenters?
- pH is monitored using probes to make sure it is at optimum value for the particular microorganism.
- Can be adjusted using acids or alkalis
30
Why is oxygen needed in fermenters?
For aerobic respiration to take place.
31
What are stirring paddles used for in fermenters?
They ensure that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed.
32
What are the benefits of fish farming
- Fish farms are ways of raising large numbers of fish in a small space to provide food for humans.
- The ability to selectively breed fish to ensure high quality, fast-growing fish
- The ability to protect against predators
- The ability to control water quality
- The ability to control feeding to ensure rapid growth
33
Methods used in fish farms to ensure high yield
- The control of water quality (water is filtered to remove waste and harmful bacteria)
- The control of intraspecific predation (fish are separated by size and age)
- The control of interspecific predation(different species are separated)
- The control of disease (fish are given antibiotics)
- The control of the quality and frequency of feeding (fish are fed with food that is high in nutrients frequently in small amounts)
- The use of selective breeding
34
How would you test a sample of 2 different types of milk to show they contain different masses of protein?
- Biuret reagent is added to the milk.
- The darker purple contains more protein.
- The same volume of milk and biuret should be used.
35
Explain why antibodies in milk are useful for babies?
- Antibodies prevent infection/disease.
- By destroying the pathogen that causes the disease.
- Antibodies provide immunity to future infections
36
How is lipid in milk used by babies?
- As a source of energy
- As store of energy
- Insulation around organs
37
What is the carbohydrate used to make yoghurt?
Lactose.
38
Why does milk needs to be heated to a high temperature at the start of the yoghurt making process?
- The heat will pasteurise milk.
- The heat will) kill microorganisms.
- This prevents competition for carbohydrate/sugar
39
Define the term limiting factor for photosynthesis?
An environmental factor that limits the rate of photosynthesis.
40
Why can plant mass be used as a measurement of rate of photosynthesis?
- Photosynthesis produces glucose
- Glucose is used by the plant in respiration
- Respiration releases energy for growth
41
