5.10 Breeding Plants

Understand that plants with desired characteristics can be developed by selective breeding

The number of rice grain per rice is under the control of genes. The farmer wants to increase the number of rice grain per plant to increase the yield. 

Some plants have 6 grains per stem, while others have 8 and 10 grains per stem (variety in number). 

The farmer's decision is to harvest the grains with 6 and 8 grains, but will use those with 10 grains for planting. 

In the next generation of rice, the grains increase to 8-10-12. And so the farmer will harvest those with 8 and 10 grains, but selective those with 12 grains for planting and breeding.

In this way, the number of grains of rice which are found on  these plants gradually increases. This means increase in yield. 

This is an example of selective breeding.

It can be applied to most characteristics of the plant. 

5.9 Fish Farming

Explain the methods which are sued 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

- low fat and high protein

- efficient at turning their nutrients into fish mass

Advantage of fish farming

- allow us to control quality of water, ensuring that it's clean

- control predators

- reduce pests

- reduce disease

We contribute to the increase of yield of fish.

Disadvantage of fish farming

- When you have a high density of fish, the possibility is the transmission of disease. Because of this, some fish farmers have been using antibiotics, which is a concern to human health. 

- Abundance of fish also makes pest, so some farmers would use pesticides, which is also a cause of concern for human body.

5.8 Fermenter

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 the growth of microorganisms

The industrial fermenter is the reaction vessel in which fermentation occurs. It is usually built out of metal such as copper or steel. Inside the steel jacket there is usually another steel jacket inside, and in between it contains water which made up the cooling jacket. Once the fermentation gets going it produces heat, and this cools down the reaction to keep temperature at optimum temperature. 

The fermenter will need to be cleaned and that's why we have a tubelike inlet which allows the steam to be pass into the fermenter. The steam will be sterilizing fermenter between fermentations (after finish producing the product and we need to clean the tank out). 

Within the fermenter there will be a heating plate to raise the temperature, which is called heater. 

Heater + Fermenter ---> Keep at optimum condition 

For fermentation to occur, we have to put nutrient into the tank, so there is a tap or pipework to insert nutrient as foods for microorganism.

To measure the internal temperature there is a temperature probe in the fermenter and it will tell us whether to apply the heater or the cooling jacket. 

The reaction will also require the addition of microorganism (so we have another tap for that). Reaction occurs inside the tank. 

We also require a pH probe as we are trying to keep the pH level at the optimum rate. 

We are also going to need a way to stir the reaction. This is going to be done by having a motor inside the fermenter and this will agitate the mixture, stopping it from clamming together and spreading the microorganism throughout the mixture.

At the end of reaction, we will need a way to drain off the product. This is called downstream processing which involves purification 

Overall, the fermenter is to keep the optimum growth conditions for the microorganisms so it is able to produce the product that we are looking for. 

5.7 Yoghurt

Understand the role of bacteria (Lactobacillus) in the production of yoghurt

1. Cow produces milk through the process of milk production. 

2. Milk goes through process called pasteurization to remove pathogens such as TB bacillus. This heat treatment kills off any pathogens in the milk. 

3. Milk sugars are converted into lactic acid. This is brought about by incubating the milk by 45-46 Celsius and add lactobacillus, which produces the enzyme that breaks down the milk sugar lactose to produce lactic acid.

4. Lactic acid results in lower pH, creating acidic condition. This causes milk proteins.

5. Milk proteins will solidify. This solidification of milk product produces what we called yoghurt. 

5.5 Beer Production

Understand the role of yeast in the production of beer

Beer-- composed largely ethanol, which is a kind of alcohol

Glucose --Yeast/Enzyme--> Ethanol + Carbon Dioxide 

This reaction is in the form of anaerobic respiration which is carried out by yeast, which is a kind of microorganism able to supply the enzyme, to bring about this convert ion.

Ethanol is often flavored by the addition of plants such as hops. 

Glucose comes from starch in a two step process: 

1. Starch -----> Maltose 

Enzyme: amylase

Source: Barley seeds, wheat seed, rice

Starch is broken down through amylase through the germination of the seed, which is the stage called malting. 

2. Maltose -----> Glucose

Enzyme: Maltase

5.4 Pesticide and Biological Control

5.4 Pesticides and Biological Control 

Understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with drop plants

Where we have large field of crop all with the same type (monoculture), they tend to be very susceptible to pests, which use crop as their food sources.

This will reduce the productivity of farming ---> loss of food & financial impact 

To overcome this farmers can use…

1. Pesticides - chemicals designed to kill the pests

Advantages

- Chemicals = easy to obtain

- Easy to apply 

- Very effective

Disadvantages

- Toxic = killing other plants and animals other than the pests, and may be harmful to humans

- Bioaccumulation = pesticides buildup through the food chain causing problems for animals in the higher trophic level. Eg DDT

- Mutation in the pests often leads to resistance = pesticides have to be applied in higher concentration --> more toxic/ no longer work --> we have to find alternative pesticides 

2. Biological Control

For example..

In Australia, Cactus A of North America was introduced to gardens, and escaped into the country side and flourishes under Australian climate and ecosystem. The cactus then starts to cover a good deal of agricultural land and it was necessary to get rid of this. 

However, there were no natural predators of such cactus in Australia, so it was necessary to introduce alien species from another country, which was a moth/larvae, which feeds on the cactus (Cactoblastis). It has no competitors and was able to eat away this cactus and remove it from the agriculture land of Australia.

This control of pests by herbivore is called biological control. 

Advantages:

- No toxic/ chemicals involved

- Less impact on man and wildlife

Disadvantages: 

- Not 100% effective

- Difficult to control = always a danger that introduced species will find alternative prey on which to feed and will not actually die out once the pest has been removed

- Difficult to math a predator to the prey (to remove your pest)

5.3 Fertilisers

Understand the use of fertilizers to increase crop yield

We can increase the growth of plants in farming by the application of fertilizers to the soil. Fertilisers are usually in the form of nitrate and phosphate, or combination of both.

These compounds go down into the soil and are taken up from the root structure, and move in the transpiration stream up to the leave.

Nitrate --> proteins

Phosphate --> DNA, membrane structure 

Fertilisers can be divided into two groups. 

1. Organic fertilizers

Produced from animal waste on farm

This usually take the forms like Cow faeces, collected by the farmer

It often goes through the process of decomposition and fermentation and form a substance known as slurry. 

This gives crop plant a supply of nitrate and phosphate to promote growth. 

2. Artificial fertilizers 

Take the forms of chemicals 

- Potassium nitrate

- Ammonium nitrate

Apply to the field, they will go into solution in the soil water. This will release nitrate and promote growth in the same way as it would do at the compound.