5a) Food production

CROP PLANTS
You can artificially create the conditions for photosynthesis:

• enclosed 
• greenhouses and polythene tunnels increase the yield of certain crops
• artificial light ---> more photosynthesis 
• trapping heat 
• increase CO2 levels 
• increase temperature 

Greenhouses and Polythene tunnels: 

• increase CO2 levels- The more carbon dioxide present, the quicker the rate of photosynthesis and so increases the growth of crops at a faster speed 
• increase temperature- increasing the temperature raises the rate of metabolic reaction so the temperature needs to be at an optimum a very high temperature denatures the enzymes and low temperatures would reduce the metabolic rate. 
• increase of light intensity 

Fertilisers;

- replace missing elements 

- organic examples ---> nitrogen, manure and animal waste 

- most are chemically produced 

- too little has no effect 

- too much is expensive for people maintaining the crops

- Important elements are Nitrogen, Phosphorus and Potassium 

Reasons for pest control: 

cause crop damage and economic loses in high population

reduce photosynthesis and growth and damage appearance  

Pesticides:

Pros-

Kills pests

Quick results 

Increase and improve crop quality 

Prevent diseases found in fruit and vegetables 

Cons- 

Often poisonous to humans, must be used carefully 

harm other wildlife

expensive  

Biological Control:

Is alternative use of pesticides to reduce pests numbers. Introduces a predator which naturally feeds on them to reduce size.
Takes some time to fully eradicate.

Example: parasitic reduce pest numbers. They lay eggs inside whitefly egg (major pests of greenhouse gases) which prevents population increase. However can't cause crop damage.

MICRO-ORGANISMS

Yeast in the production of food:

1. Barley seeds are the main basis of beer. Seeds are germinated in large warehouses. The seeds produce an enzyme amylase during this.
2. Once the seeds have germinated they are killed and died, creating malt. The malt contains lots of amylase.
3. Malt is ground up and mixed with water in a mash tun (large container). During this time the amylase breaks down starches in the ground up seed mixture, converting it to sugars such as maltose and glucose.
4. Mash is boiled and filtered. Boiling results in denaturing of the amylase enzymes in the mixture. It must be filtered to remove residues of malt. 
5. Hops are added to the filtered solution and yeast is added. The yeast ferments sugars in the mixture creating carbon dioxide and alcohol as a result. 
6. The resulting mixture is high in alcohol and contains much carbon dioxide however it also contains yeast cells and hops. The beer is must be centrifuged, filtered and is sometimes pasteurised.
7. Beer is put into casks or barrels.  

The respiration rate of yeast:

The optimum temperature for yeast growth is 35-40C, if the temperature is too high enzymes become denatured. 

Glucose    --> Carbon Dioxide +   Alcohol 

C6H12O6 -->        2CO2        + 2C2H5OH     

Paper Two - Role of bacteria in the production of yoghurt:

• Yoghurt is made by the fermentation of milk by the bacteria called Lactic Acid Bacteria 
• This means that the bacteria respires anaerobically 
• Fermentation turns the liquid milk into a slightly sour semi solid food this is due to the lactic acid 
• Sugar in the yoghurt gives it energy and taste 
• Due to the build up of lactic acid the yoghurt has a low pH level- this prevents other micro-organisms from growing into the yoghurt 

(Lactose -->) Glucose --> Lactic Acid + Energy

                 C6H12O6 --> 2C3H6O3 (+ energy) 

Industrial Fermenter:

Containers are used to grow bacteria and fungi in large amounts 

FISH FARMING 

Problem: fish are being driven to extinction 

Cause: overfishing, high demand and sushi 

Solutions: growing fish in enclosed areas, QUOTAS, license, make fish more expensive and tax

Open and Closed Farming:

+------------------------------------+---------------------------+
| Advantages                         | Disadvantages             |
+------------------------------------+---------------------------+
| control oxygen and temperature (C) | disease spreads rapidly   |
+------------------------------------+---------------------------+
| meet demands (C+O)                 | cost of food (C)          |
+------------------------------------+---------------------------+
| introduce new breeds and fast      | pollution from faeces     |
| growth                             |                           |
+------------------------------------+---------------------------+
| fish manure well (O+C)             | fish in tanks are carniv- |
|                                    | orous and hungry          |
+------------------------------------+---------------------------+
| surviving a predator attack (C)    | fined for: traces of      |
|                                    | antibiotics               |
+------------------------------------+---------------------------+
|                                    | fined for: reduction      |
|                                    | of non-harmful organisms  |
+------------------------------------+---------------------------+