5.11 Breeding Animals

- The animal in the video is a cow. The desired characteristic is milk yield.
- The earliest farmers notice that a few cows will produce a small amount of milk each time. around 50 ml each time that they are milked.
- Other cows, a few, will produce 150 ml of milk
- Most cows produce 100 ml of milk.
- The farmer will collect all the milk
- He chooses the cows that make 150 ml of milk to become his breeding cows.
- In the next generation of cows, we find out that a few cows produce 100 ml of milk, very few produce 200 ml of milk and the majority produce 150 ml of milk
- The farmer selects his breeding cows from the one that produce 200 ml to become the breeding population
- perhaps, in the next generation, a few cows will produce 150 ml of milk, most cows will produce 200 ml and few produce 250 ml
- as we progressively select, we change the desired characteristic. We are able to develop the desired characteristic by selective breeding
- for this to work, milk yield must be genetic - under the control of genes.

5.10 Breeding Plants

- In the image, the plant is rice. On the rice there are rice grains
- the number of rice grains are under the control of genes
- the farmer wants to improve the number of rice granes per plant which would lead to the increase in yield
- Some plants have six grains per stem whilst others have 8 grains per stem as well as others that have 10 grains per stem
- the farmer decides to harvest the one with 6 and 8 grains and use the one with 10 grains for planting
- in the next generation of rice, the number of grain increases to 8 grains per stem, 10 grains per stem and 12 grains per stem.
- he harvests 8 grains and 10 grains and selects the one with 12 grains for planting and breeding
- this way, the number of grains of rice on each plant gradually increases --> therefore, the yield increases.
- this is an example of selective breeding and can be applied to most characteristics of the plant.

5.9 Fish Farming

- fish is an attractive product for farmers because:
1. they have low fat and high protein
2. they are efficient at turning their nutrient into fish mass

Pros:
- fish faming allows us to control the quality of water = clean
- we can control predator's
- we can reduce pests
- we can also reduce diseases

- By controlling all these factors, we contribute to an increase in yield of fish.
- However, where you have a high density of fish, there is a possibility of transmission of disease.
- Because of this, some fish farmers have taken to using antibiotics and is a concern to human health
- The abundance of fish within the fish farm also makes pests common and therefore, some fish farmers use pesticides - this is also a cause of concert amongst humans.

5.8 Fermenter

- Fermenter = the reaction vessel in which fermentation occurs.
- the vessel is usually built of metal, e.g. copper, steel, etc.
- normally, there is another steel jacket inside the first steel jacket
- in between the two jackets, there is water = cooling jacket. once a fermentation gets going, it produces heat and the water cools down the reaction so it occurs at optimum conditions.
- the fermenter needs to be clean and therefore, there is an inlet. Steam goes through the inlet and it will be sterilizing the fermenter between fermentations.
- within the fermenter, there is a heating plate to raise the temperature.
- the heater and the cooling jacket allows us to control the optimum conditions for fermentation.
- there is a tap/pipe work to insert nutrients
- there is a temperature probe = it will tell us whether to deploy the heater or the cooling jacket
- the reaction require addition of organisms, therefore, there will be another tap for it.
- a pH probe is also required - to monitor and keep it at the optimum temperature to get the maximum rate of reaction
- to stir the reaction, a motor is required and this will agitate the mixture, stopping it from clumping together

- the idea of the fermenter is to create a reaction centre in which we control the optimum growth conditions for the micro-organism so that it will be able to produce the product that we are looking for
- at the end of the reaction, the important thing is to find a way to drain off the product which would then go on to the process called down stream processing which involves purification

5.7 Yogurt

- The process starts with a cow and milk is produced
- Pathogens such as TB bacillus is removed from the milk through the process called pasteurisation
- The milk sugars are converted into lactic acid, this is brought about by incubating the milk at 45 - 46 degrees and to add lactobacillus (lactobacillus produce the enzymes that break down the milk sugar, lactose into lactic acid)
- The acid will result in a lower pH (acidic conditions) and this causes milk proteins. The milk proteins then solidifies. The solidification is 'yogurt'

5.5 Beer Production

- the beer is largely: Ethanol - an alcohol molecule
- Anaerobic respiration: glucose --(yeast)--> ethanol + carbon dioxide
- yeast is able to supply the enzymes to bring about the conversion
- the ethanol is flavoured by the addition of plants (e.g. Hops)
- glucose comes from starch in a two-step process
- Starch --(enzyme: amylase)--> maltose --(enzyme: maltase)--> glucose
- the source of the starch are things like: barley seeds, wheat seeds and sometimes rice
- malting: breaking starch down to maltose through the germination of the seed
- yeast brings about the anaerobic respiration of glucose, ethanol and carbon dioxide

5.4b Biological Control

example of biological control - not using pesticide:
- In Australia, the prickly pear cactus, which was the pest, of north america was introduced to gardens
- it escaped into the countryside
- it flourished under the Australian climate and the ecosystem
- the cactus started to cover a deal of agricultural land and was necessary to get rid of it
- there was no natural herbivore of the cactus and was necessary to introduce an alien species from another country = a moth which feeds on the cactus, known as Cactoblastis
- the moth was introduced and had no competitors = able to eat away at the cactus and remove it from the agricultural land of Australia

Pros:
- There are no toxic chemicals involved
- this leads to less impact on man/wildlife

Cons:
- not 100 percent effective
- often difficult to control - there is always a danger that the introduced species will find alternative pray on which to feed and will not die out once the pest has been removed
- difficult to match a predator to the prey