5.9 Fish Farming

5.9 explain the methods which are used to farm large numbers of fish to provide a source of protein, including maintenance of water quality, control of intraspecific and interspecific predation, control of disease, removal of waste products, quality and frequency of feeding and the use of selective breeding.

Fish Farming is attractive to farmers because fish are low in fat; high in protein and highly efficient at transferring nutrient into fish matter.

Benefits to fish farming

• Water quality can be controlled
• Predators can be removed
• Pests can be removed
• Disease can be controlled

Controlling these factors increases the yield of fish.

However the high density of fish in fish farms makes the transmission of disease and number of pesticides greater so farmers use antibiotics and pesticides to control this but as we know, this can cause harm to humans and the environment.

5.8 Fermenter

5.8 interpret and label a diagram of an industrial fermenter and explain the need to provide suitable conditions in the fermenter, including aseptic precautions, nutrients, optimum temperature and pH, oxygenation and agitation, for growth of microorganisms

Fermenter – the reaction vessel where fermentation occurs. The aim is to have optimum growth conditions for fermentation to occur.

• Inlets
• Steam – cleaning
• Microorganisms
• Nutrients
• Probes
• pH
• Temperature
• Water Jacket and Heater for temp control
• Stirrer – to agitate the mixer

5.7 Yoghurt

5.7 understand the role of bacteria (Lactobacillus) in the production of yoghurt

1. Cow milk is pasteurised to remove harmful bacteria.
2. The milk sugars are converted into lactic acid
• Incubated at 45-46°C
• Add lactobacillus (enzyme)
3. The acid creates acidic condition
4. Milk proteins solidify to yoghurt

5.5 Beer

5.5 understand the role of yeast in the production of beer

Glucose is converted from Starch by Amylase and Maltase. The Starch is usually from Barley seeds.

Anaerobic Respiration (Fermentation
Glucose ----yeast/enzymes---> Ethanol + Carbon dioxide

Hops are then added to the ethanol for flavouring.

5.4 Pest control

5.4 understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants

A large field of crops of the same type is called a monoculture. These are very susceptible to pests which use the crop as their food source which reduces crop yield for the farmers.

Pesticides
To overcome this pesticides are used – Chemicals designed to kill the pests

Advantages

• Chemicals – easy to obtain
• Easy to apply – spray
• Very effective

Disadvantages

• Toxic – harmful to other species other than the pests (inc. humans)
• Bioaccumulation – the pesticide causes problems in the higher levels of the food chain
• Mutation in the pests leads to resistance.

Biological Control
Biological control is reducing the population of a pest without using pesticides.

For example if pest enters a country and flourishes it is often important to attempt to remove this species so that the native species can flourish again. In order to do this another alien species must be brought in that is higher in the food chain to reduce the numbers of the problematic plant/animal

Advantages

• No toxic chemicals
• Less impact on man/wildlife

Disadvantages

• Not 100% effective
• Difficult to control
• The alien species may not die out once the pest has been removed and could become another problem

5.3 Fertilisers

5.3 understand the use of fertiliser to increase crop yield

To increase crop yield in agricultural farming fertilisers are added to the soil. Fertilisers are usually nitrates, phosphates, or a combination of the two. The compounds enter the plants through the roots in the soil and move through the transpiration stream to the leaf
Nitrates -> Proteins
Phosphates -> DNA/ Membrane structure

Fertilisers can be divided into two groups

1. Organic fertilisers
• Animal waste – cow faeces
• Decomposed/fermented
• Manure (slurry)
2. Artificial fertilisers
• Chemicals - Potassium Nitrate and Ammonium Nitrate
• Applied in solution to release nitrates and phosphates

5.2 Crop Yield

5.2 understand the effects on crop yield of increase carbon dioxide and increase temperature in glasshouses

Rate of photosynthesis:
CO₂ + H₂O ----light/enzyme---> C₆H₁₂O₆ + 6O₂

Increasing the concentration of Carbon dioxide (substrate) will increase the rate of photosynthesis producing a higher yield up until a given point.

Increasing temperature shall also increase the rate of reaction we reach the optimum temperature for the enzymes in photosynthesis. After the peak there is a sudden asymmetrical drop as the enzymes denature.

Increasing temperature also contributes to avoiding frost damage and an increased yield