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 waster products, quality and frequency of feeding and the use of selective breeding

Fish farming is a possible solution to the problem of overfishing. It is controlled and designed in a way to produce as many fish as possible.

NOTE: Everything specifically to do with fish farming in cages in the sea is in blue, everything specifically to do with fish farming in tanks is in green.

Maintenance of water quality
There is a current in the sea so water is naturally kept 'clean'.
The water can be removed, filtered and cleaned. Water can be monitored to ensure temperature, [H and oxygen level is at the best potential.

Control of intraspecific and interspecific predation

Firstly, interspecific predation is being eaten by other animals, intraspecific predation is cannibalism, basically.

Fish farming in cages stops interspecific predation as it means no animals/fish can eat the farmed fish. Big fish and baby fish are kept separate to keep intraspecific predation low.

Control of disease

Fish in cages are prone to diseases such as lice . Biological pest controls are used to control the lice as chemical pesticides can harm the fish.

Removal of waste products

The water can be removed and filtered, getting rid of waste.

Quality and frequency of feeding

A diet of food pellets is carefully controlled to maximize the amount of energy the fish get as more energy = more growth = bigger fish. Furthermore, the better the quality of food, the bigger the fish will grow.

It is easy to control how much food is given, as it doesn't wash away in the current of the sea.

Selective breeding

The fish can be selectively bred to produce fast growing, less aggressive fish, for example.

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 the growth of micro-organisms

Okay so to start, here is a diagram...

Conditions...

The fermenter must be kept aseptic so only the desired microorganism grows. In order to do this, it is cleansed (usually with steam) before production takes place.

Nutrients are provided to ensure that the microorganisms always have enough food to grow.

The optimum temperature and pH is maintained and monitored with probes (connected to a screen)  to ensure maximum growth. Also, if the temperature is too high, the enzymes will denature. An optimum temperature needs to be kept to ensure the best yield.

If the process requires aerobic respiration (not beer, for example, which requires anaerobic respiration of yeast to make ethanol), there is an oxygen supply.

Agitation/stirring takes place to ensure that the microorganisms, nutrients and temperature are evenly distributed.

image credit: BBC

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

Lactobacillus is the bacteria that ferments milk (into yoghurt) in yoghurt production. This is the process...

- All equipment is sterilized in order to kill off any unwanted micro-organisms.

- the milk is heated to 72° for 15 seconds (pasturisation) in order to kill any germs in the milk.

- the milk is cooled

- The bacteria 'lactobacillus' is added.

- the mixture is incubated at around 40° in a fermenter. This is where the bacteria ferment the lactose sugar in the milk, forming lactic acid

- The lactic acid causes the milk to clot, causing it to solidify and turn into yogurt.

- Any flavourings/colourants are added

- the yogurt is packed

5.6 describe a simple experiment to investigate carbon dioxide production by yeast, in different conditions

When yeast respires aerobically, it produces carbon dioxide as a bi-product. Here is how to measure the effect of changing temperature on carbon dioxide production from yeast...

- mix together some suger, yeast aand distilled water. Add this mixture to a test tube

- attatch a bung with a delivery tube. Attatch the other end of the delivery tube to a test tube of water

- Put the tube containing the yeast/water/sugar solution in a water bath at 10°.

- leave to warm up for 5 minutes and then count how many bubbles are produced in one minute

- repeat with 4 other test tubes, one at 15°, one at 20°, one at 25° and one at 30°. You should also do one at room temperature as a control

- plot results in a graph and compare/find patterns/anomalies

should all go well, you should conclude that as temperature increases, the rate of respiration (and therefore amount of bubbles) should increase. However, if you have done a water bath past optimum temperature for the enzymes (as respiration is controlled by enzymes), then there will be very little/no data for this tube.

NOTE: You can use the same apparatus but measure the effect on different concentration of sugar, for example, by keeping the water bath the same temp but adding more/less sugar to each tube. the same can be done with volume of water and/or concentration of sugar solution etc

5.5 understand the role of yeast in the production of beer

When yeast respires anaerobically (without enough oxygen) it produces ethanol/alcohol as a bi-product. In beer production, yeast respires anaerobically. It is the ingredient in the production of beer that makes the alcohol, it ferments the sugars into alcohol.

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

Pesticides/pest control kills insects/microorganisms/mammals that feed on crops. they are useful as they are very effective. However, they are poisonous to humans so must be used carefully around foods etc (e.g. growing carrots) and some pesticides are harmful to other wildlife.

Biological control is an alternative to pesticides, it involves using other organisms to control pests (e.g. introducing hoverflies to an area to reduce the amount of aphids, as aphids kill hoverflies). This has a longer lasting effect on the crop/area than pesticides do and is less harmful to the ecosystem. However, it can cause problems. for example, the introduced species could become uncontrollable and their predator would have to be introduced to control them. It can also take longer (potentially).

5.3 understand the use of fertiliser to increase crop yield

If plants don't get enough nitrogen, potassium or phosphorus, their growth and other life processes could be affected.

These elements are naturally found in the soil, however, they could be lacking due to previous crops using them up. All fertilisers do is replace them in the soil, so the plants can grow very well.

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

Okay so, I mainly covered this, along with other factors, in point 5.1, but here it is again...

If carbon dioxide is increased, the rate of photosynthesis will be increased. Meaning more photosynthesis will occur each day, meaning a bigger crop yield.

If temperature is increased, plants can grow throughout the winter and don't die of frost etc. This also lowers the rate of transpiration (as there is a lower concentration gradient inside vs outside the plant leaf so the rate of transpiration is lower).

5.1 describe how glasshouses and polyethene tunnels can be used to increase the yield of certain crops

Glasshouses and polyethene tunnels/polytunnels help to create the ideal conditions for plants, thus increasing the yield (how much grows) of a crop. Some ways they create the perfect conditions are...

- The plants are enclosed, meaning they are at no/a significantly lower rick of pests and diseases.

- Artificial light can be supplied which will increase the time per day a plant is photosynthesizing

- The suns heat can be trapped (particularly in glasshouses). This keeps the plant warm. In winter it can stop the plants from being damaged by frost etc

- As it is an enclosed space, farmers can increase the level of carbon dioxide in the glasshouse/polyethene tunnel. They can do this by burning a paraffin lamp etc (combustion fossil fuels gives carbon dioxide). This further increases the amount/rate of photosynthesis the plant endures.

All of the above increase the yield of a plant.