Food Production Flashcards
Benefit of glasshouses and polythene tunnels
Growing crops outside does not allow farmers to control limiting factors
In an enclosed environment, farmers can control the climate to improve crop yields
Glasshouses function
Increase rate of photosynthesis:
Artificial heating (enzymes work at optimum)
Artificial lighting (longer photosynthesis)
Increasing CO2 content of air (quicker photosynthesis)
Regular watering
Problems with glasshouses
Farmers need to balance extra cost of maintaining its conditions against the increased income
Ventilation required to release hot air in tropical countries as temperatures are hotter
Too high a temperature can denature enzymes
Polythene tunnels function
Large plastic tunnels that cover crops
Protect crops grown outside from weather e.g. wind/rain/extreme temperatures
They increase temperature slightly inside the tunnel
They can prevent entry of pests or diseases
Fertiliser function
As crops are grown repeatedly in the same field, mineral ions in soil are used up
Fertilisers (e.g. manure, spray) replace mineral ions
They can make crops grow faster and bigger
Yield increases
Pros and cons of organic fertiliser
Cheap
Readily available
Sustainable
Slow release of ions (decomposition)
Improves soil structure/stops erosion/holds water
Can only replace portion of lost nitrogen
Pros and cons of inorganic fertiliser
Fast release of ions
Formulated to provide specific amount of nitrates
Needs to be manufactured
NKP combination used for better growth
Expensive
Unsustainable
More eutrophication: high conc. of soluble nitrate ions
Nitrogen ions
Absorbed as nitrates
Needed to make amino acids for proteins
Lack of nitrogen -> weak growth, yellowing of leaves
Phosphorous ions
Absorbed as phosphates
Needed to make DNA and cell membranes
Lack of phosphorous -> poor root growth, discoloured leaves
Potassium ions
Absorbed as various compounds of potassium
Allows enzyme reactions to take place in photosynthesis and respiration (ATP)
Lack of potassium -> Poor growth of flowers and fruits, brown spots on leaves
Effect of pests on crops
Pest e.g. insects damage crops by eating them
Weeds outcompete crops for space, water and soil nutrients
Fungi infect crops and spread disease (lower yield)
Advantages of pesticides
Easily accessible and cheap
Have an immediate effect
Kills the entire population of pests
Disadvantages of pesticides
Pests can develop resistance to them
Also kill other beneficial organisms (e.g. bees)
Larger organisms cannot reproduce as rapidly as pests
Bioaccumulation of chemicals at top of food chains in great concentrations, harming top predators
Needs to be repeatedly applied
Advantages of biological control
Natural predator to eat pests - no pollution
No resistance
Can target specific species
Long lasting
No need to be repeatedly applied
Disadvantages of biological control
May eat other organisms instead of the pest
Takes longer to be effective
Cannot kill entire population
Predator may not adapt to new environment
Predator may become a pest itself
Yeast cell
Fungal: Nucleus, mitochondria, cell membrane, cytoplasm ribosomes, chitin cell wall
Role of yeast in making bread
Yeast is added to bread dough, producing enzymes that break down the starch in the flour into sugars
The yeast uses these sugars to respire aerobically
Once oxygen runs out, yeast respire anaerobically, producing ethanol and carbon dioxide
The CO2 produced is trapped in air pockets in the dough, causing it to rise (increase in volume)
The dough is baked, evaporating the ethanol
The yeast are killed by the high temperatures
Role of yeast in making beer
Barley (containing starch) is mashed and put in hot water to activate amylase (starch -> maltose)
Yeast is added, fermenting the maltose
Investigating carbon dioxide production in yeast
Mix yeast with boiled sugar solution (remove oxygen) in a boiling tube (provides glucose for anaerobic respiration), add diazine green solution: blue if O2 present, pink if not present
Add layer of oil on the solution (prevents oxygen entering and therefore prevents aerobic respiration)
Once suspension turns pink (no oxygen), attach a delivery tube + bung (prevent CO2 escaping) leading to hydrogen carbonate indicator or limewater
Place the boiling tube in a water bath for a set temperature and fixed time (e.g. 2 mins)
Measure the time taken for indicator to change colour to yellow (red at atm. levels)/count bubbles produced
Change temp of water bath/conc. or vol. of glucose/pH depending on experiment
Role of bacteria (Lactobacillus bugaricus) in producing yogurt
All equipment is sterilised to kill unwanted bacteria and prevent chemical contamination
Milk is pasteurised at 85-95°C to kill bacteria
Contamination would slow production(competing for lactose)/spoil taste (lactose -> lactic acid)
The milk is cooled to 40-45°C, Lactobacillus is added
The lactic acid released increases acidity, souring and thickening the milk to form yoghurt
Acidity also prevents growth of other microorganisms
Yoghurt is then cooled to 5°C to halt bacteria
Industrial fermenters usage and components
Containers used to grow cultures/microorganisms like bacteria and fungi in large amounts
Used to make food, but also antibiotics e.g. penicillin
Conditions can be carefully controlled
Steam inlet, Nutrient inlet, cooling water inlet, air inlet
Exhaust outlet, product outlet, cooling water outlet
Water jacket, stirring paddles
Controlling aseptic precautions
Fermenter is cleaned by steam to kill microorganisms and prevent chemical contaminations
Only desired microorganisms will grow
Controlling nutrients
Nutrients are needed for respiration
Microorganisms can grow and reproduce
Controlling temperature
Temperature monitored using probes and maintained by water jacket
Optimum temperatures for enzyme activity
Controlling pH
pH monitored using probes and adjusted using acids or alkalis
Optimum pH for enzyme activity
Controlling oxygen
Oxygen is needed for aerobic respiration
Controlling dispersion
Stirring paddles distribute microorganisms, nutrients, oxygen, temperature and pH evenly
Advantages of Fish Farming
Water quality monitored: temp/o2/clarity/chlorophyll
Water conditions can be modified
Can predict algal blooms (toxic to fish)
Control of diet
Fish are protected against predators
^Intra/Interspecific predation (size+age / species)
Control of disease (antibiotics)
Selective breeding
These all result in high yields of healthy fish
Disadvantages of Fish Farming
Greater spread of disease (close together)
Antibiotics in fish eaten by humans (health concerns)
Contaminated water around farm (feces, food pellets)
Pesticides used are harmful to other organisms
Aquatic ecosystems destroyed to sustain fish farms
Several kg of wild fish to produce 1kg of farmed fish
