Food Production

Amount of light (sunlight or artificial)
Amount of carbon dioxide
Temperature
All three factors affect a plant's rate of photosynthesis

Keeping plants enclosed makes it easier to keep them free from pests and disease
Helps farmers control the volume of water supplied to the crops
Allows farmers to supply artificial light after the Sun goes down to give the plants more time to photosynthesise
Glasshouses trap Sun's heat to keep the plants warm
In winter, farmers can use a heater to help keep the temperature at the ideal level
Farmers can increase/control the level of carbon dioxide by using using a paraffin heater which makes carbon dioxide as a by-product
By increasing the temperature, CO2 concentration and light intensity, a farmer can increase the rate of photosynthesis, meaning that the plants will grow bigger and faster and crop yields will be higher

Plants need certain minerals (nitrogen, potassium, phosphorous) to make important compounds for the plant (proteins, DNA, chlorophyll) and if they don't get enough of these minerals than their growth is stunted and their life processes are affected
Farmers use fertilisers to replace missing minerals that might have been used by other plants and to provide more of them, helping to increase crop yield as the plants grow bigger and healthier

Pests that feed on crops damage or destroy the crops so if there are fewer pests then fewer plants are damaged or destroyed, increasing crop yield

Getting rid of pests by introducing their predator into the environment

Specific (only kills target species)
Maintains low levels of pests (so no need to reapply)

Requires specific knowledge of food chains
Expensive (but only need to apply once)
Slow
Doesn't reduce pests to zero

Cheaper (but needs to be constantly reapplied)
Very quick

Pests become resistant
Constantly need to reapply (pests come back)
Pests could avoid death by hiding (being inaccessible)
Bioaccumulation (builds up in food chain)
Kills other animals and plants (harmful to wildlife)

Bread dough is made by mixing yeast with flour, water and sugar (because sugar contains glucose and glucose is required for the yeast to respire)
Dough is left in a warm place to rise (heat increases kinetic energy, increasing the number of enzyme-substrate collisions, increasing the rate of respiration)
Enzymes break down carbohydrates and sugars into glucose
Yeast then uses the glucose in aerobic respiration, producing carbon dioxide
When oxygen runs out, the yeast switches to anaerobic respiration, producing carbon dioxide and ethanol
Carbon dioxide is trapped in bubbles in the dough
These pockets of gas expand and the dough begns to rise
The dough is then baked in an oven where the yeast continues to ferment until the heat kills it along with any ethanol produced during anaerobic respiration
As the yeast dies, the bread stops rising but pockets are left in the bread where the carbon dioxide was trapped

Mix together some sugar, yeast and water in a test tube
Add a layer of oil to the top of the mixture to prevent oxygen from getting into the mixture to create anaerobic conditions
Place the mixture in baths of different temperatures and calculate the volume of gas produced
As the temperature increases, the volume should increase as the rate of respiration has increased

When microorganisms break sugars down to release energy

Equipment is sterilised to kill off any unwanted microorganisms
Milk is pasteurised (heated up to 72degrees for 15 seconds) to kill any harmful bacteria then the milk is cooled
Lactobacillus bacteria are added and the mixture is incubated (heated to about 40degrees) in a vessel called a fermenter
Lactobacillus bacteria ferments the lactose sugar in the milk to form lactic acid
Lactic acid causes the milk to clot and solidify into yoghurt

Fermenter full of liquid 'culture medium' which provides the nutrients microorganisms need for growth
Conditions are kept at optimum level for growth to maximise the product yield
pH is monitored and kept at optimum level for the microorgansims' enzymes to work efficiently, keeping the rate of reaction and product yield as high as possible
Temperature is monitored and kept at optimum level and a water-cooled jacket makes sure it doesn't get so hot that the enzymes denature
Vessels are sterilised between uses to kill harmful microbes and having aseptic conditions means that microorganisms are't competing with other organisms and the product doesn't get contaminated, increasing crop yield
Oxygen is pumped in so the microorganisms can respire to provide energy for growth, increasing product yield
Paddles circulate microorganisms around the vessel so that they are kept in contact with fresh medium, increasing the crop yield because they can always access the nutrients needed for growth

When fish are bred in tanks or fenced areas for consumption

Kept in cages/enclosed areas to stop them using as much energy (so that energy is used for growth)
Protects them from interspecific predation (being eaten by other species)
Fed proteinacious food little and often to increase growth
Seperated by size so intra-specific competition (same species) is reduced
Seperate males and females and selectively breed (so that babies are strong and healthy)
Remove dead or diseased fish so that disease doesn't spread
Vaccination
Oxygenate water (in tanks)
Maintain water quality (clean away waste food and fish faeces to prevent bacteria from spreading)
Control water pH (in tanks)

Occurs when toxins build up in a food chain