Food Production Flashcards
Why do farmers grow there crops in greenhouses?
- farmers want to get maximum yield for there crops
- this means they have to control the environment the crops are in to help produce a bigger yield
- they cannot control the environment in an open field, but can in a greenhouse
What are the benefits of growing crops in a greenhouse?
- transparent material allows allows natural light for photosynthesis.Artificial light gives light during winter when there is none
- the greenhouse effect raises temp
- burning fossil fuel gives additional heat, and produces CO2 and water vapour
- this water vapour increases humidity, so lesss water is lost to transpiration
What can the farmers control within the greenhouse ?
- heat
- light
- CO2 in the air
- amount of water the crops get
What are fertilisers?
They provide elements needed by plants to grow
What is nitrates needed for?
Production of Proteins
What are magnesium ions needed for?
Production of chlorophyll
What are the two types of fertilisers?
- organic
- inorganic
What are organic fertilisers?
- made from faeces, sometimes mixed with straw, and compost from legumes
What are inorganic fertilisers?
- inorganic compounds carefully formulated to yield a specific concentration of a particular ion when applied according to the manufactures instructions
Advantages of organic fertilisers
- improves soil structure
- greater range of minerals
- releases minerals over a longer period of time
- cheap as already available on the farm
(Manure)
Disadvantages of organic fertilisers
- slow acting, has to be decomposed first
- bulkier, harder to apply
- may contain pests
Advantages of inorganic fertilisers
- mineral ions release immediately so are fast acting
- contents are known
- easy to apply
Disadvantages of inorganic fertilisers
- can lead to eutrophication
- more expensive that organic
- only contains certain mineral ions
What is another way to replace lost nitrates than using fertilisers?
- grow legume crops, such as clover
Why would you grow legume crops?
- these plants have nitrogen-fixing bacteria in nodules on their roots
- they convert nitrogen gas in the air into ammonium ions
- some is passed to the plants it make proteins
- when the crop is ploughed the protein in the crop decomposes and ammonium is released into the soil
- this ammonium is then converted to nitrate by nitrifying bacteria and is available for the next years crops to use
What are pests?
They are organisms that reduce the yield of crop plants or stock animals
How can pests be controlled?
- chemicals called pesticides
- using other organisms to reduce the number of pests ( biological control )
What are pesticides that kill plants called?
Herbicides
What are the pesticides that kill insects called?
Insecticides
What are the pesticides that kill fungi called?
Fungicides
What are pesticides that kill molluscs called? (Snails and slugs)
Molluscicides
Why can pesticides damage the ecosystem?
Often the pesticide molecules are passed higher up the food chain, becoming concentrated in the tissue of the top carnivores
Why might farmers not kill pests?
- the cost of pesticides are expensive and if the pest isn’t in large numbers it might not cause excessive damage
- the increase in income must be set against the cost of pesticides
What is biological control?
Using a predator species rather than a toxic chemical to reduce the numbers of pests
Why does biological control never eradicate the pest?
- otherwise the organism that killed off the pest would die too
- the aim is to reduce the pest numbers to a level where there is no longer a significant economic damage
Advantages of pesticides
- reduces pest population instantly
- can kill the whole population of pests
Disadvantages of using pesticides
- cost
- not specific to the pest itself, can kill other insects or plants that are useful such as pollinating insects
- pests can become resistant to chemical
- chemicals can concentrate in all organisms higher in the food chain
- eutrophication can occur
Advantages of biological control
- organism only introduced once as it will reproduce
- only one cost for initial introduction
- pest specific
- pest will not become resistant
- no effect on other animals in the food chain
Disadvantages of biological control
- takes time to reduce pest population
- not all population killed
- expensive if re-populating is required
- organism can reproduce rapidly and cause disruption
What is the anaerobic equation in plants and fungi?
Glucose ——> ethanol + carbon dioxide
What breaks down the glucose in brewing ?
The anaerobic respiration of yeast
What is the alcohol in beer?
Ethanol
What is the source of sugar in beer?
Malted barley
Why is hops added?
To add flavour
What bacterium is used to make yoghurt?
Lactobacillus Bulgaricus
Describe beer production
- Barley is mixed with water and left malt
- germinating barley seeds make amylase to digest starch and amylase breaks down starch to maltose
- malted barley is dried and crushed, the mixed with water and mashed
- mash is boiled and filtered
- hops are added for flavour
- Aftercooling yeast is added and the mixture is fermented in tanks, yeast respires anaerobically releasing carbon dioxide and ethanol
- beer is cleared= A chemical clears the yeast make it settle at the bottom of the tank
- beer is pasteurised and any remaining microorganisms in the mixture are killed making it safe for sale
Describe yoghurt production
- milk is pasteurised at 90° to kill any harmful microorganisms
- milk is homogenised to disperse any fat globules
- milk is cooled to 40-45° so lactobacillus bacteria can be introduced without it being denatured
- incubated at 40 to 45°C for several hours, to allow the lactobacillus to digests the milk proteins and ferment lactose to lactic acid
- The yoghurt mixture becomes thick, as the lactic acid makes the pH become acidic making milk proteins coagulate
- yoghurt is stirred and cooled to 5°
What is the purpose of the cooking jacket?
Removes the heat energy, stopping the fermenters enzymes denaturing
What’s the purpose of the air filter?
Filters air coming in, maintaining sterile conditions
What’s the purpose of the stirrers?
Keep the broth well stirred to oxygenate all parts of the fermenter and prevent micro-organisms settling
What is purpose of the growth medium?
Contains all necessary glucose and amino acids for micro-organism growth
What is the purpose of super-heated steam?
Applied before the fermenter is used, killing unwanted micro-organisms
How do farmers make their fish grow large?
- feed high lipid and protein food to promote rapid growth
- regular feeding with small amounts so all is eaten
- selective breeding
What happens when there is more than one species of fish in a pond?
- Interspecific competition = different species will compete for food and some species may be wiped out
- predation = Carnivorous species will prey on other fish
What is the solution for interspecific competition?
Place different fish in different tanks
What is the solution for predation?
Placing A cover on top of the ponds will reduce predation from birds
What happens if you put too many individuals in one pond?
- intraspecific competition = larger individuals will outcompete smaller individuals for food or large individuals may prey on smaller individuals
- infectious disease = parasites and pathogens spread quickly if the fish are too close together
What is the solution having too many individuals in one pond?
- separate fish by age and size
- remove infected fish quickly and add antibiotics to the water to kill bacteria
How do fish farms affect the environment?
- Fish may escape and outcompete or interbreed with local species
- parasites or pathogens can be introduced into ecosystems by farming fish
- Excess food and waste from fish can cause eutrophication
