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

Have a test tube of yeast in glucose solution. Put a layer of oil on top if you want the yeast to respire anaerobically (as it will prevent oxygen entering the solution.)

Put the test tube in a water bath, heat the water to vary the temperature.

Collect gas coming off in a tube then: count the bubbles; use downwards displacement.

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 are a source of protein in many diets, humans consume a lot of fish for this reason. Fish farms are used to supply fish because: the fish's food safety standard is monitored; fresh water fish are declining; the deman for fish is increasing.

Fresh water fish may have come into contact with unclean water; containing sewage, waste, chemicals. In fish farming the water is filtered to make sure the fish don't come into contact with anything it would be unsafe to digest. Also if the water is cleaned regularly the spread of disease is minimised and the oxygen levels are high enough to maintain the respiration of the fish.

Intraspecific predation is the fish being bred eating each other, this can be stopped by: separating fish of different ages; separating fish of different genders; feeding fish regularly; giving fish adequate room.

Interspecific predation is the farmed fish being prayed on by other species, this can be prevented by: fencing the area the fish are in; putting nets around the area the fish are in; keeping the fish in inside tanks.

To minimise spread of disease, the water the fish are in should be changed regularly and their surroundings sterilised often. Also if small amounts of fish are kept together then disease can only contaminate a few fish.

Waste can be removed by changing the water in a tank, or changing the nets and location of fish kept outside.

Fish need to be fed often in small amounts, this is so they don't starve but they wont be able to over eat. It is important to feed fish food with nutrients in for growth.

Selective breeding can ensure that farmers produce fish with desired characteristics  by letting only the fish with the right characteristics breed and pass on the gene.

A useful source is: http://www.scribd.com/doc/79750837/Fish-Farming

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

Here is a diagram of a fermenter, the key parts are labelled:

eplantscience

The motor (labelled here as stirrer) turns the blades, this evens out the mixture: making sure the temperature and concentration is the same through out; and increasing the contact between the micro-organisms and other components.

The cooling jacket (labelled here as water column) controls the temperature as the cool water conducts heat from within. The temperature and PH both need to be monitored so that they can be kept at the optimum level for the enzymes. If the enzymes are in their optimum conditions then they will react faster.

Inoculum is the starter culture; basically it helps the fermentation start.

The air inlet gets oxygen into the fermenter. Oxygen is needed for the micro-organisms to respire. A sparger/agitator makes the air into very small bubbles; this means they have a larger surface area and can dissolve easily, so there is better access to oxygen for micro-organisms.

Aseptic conditions are needed as if there were other microbes in the fermenter; firstly they would contaminate the product; secondly they would use up nutrients and oxygen.

Nutrients are needed in the fermenter so the micro-organism can grow.

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

When Lactobacillus respire anaerobically, they make lactic acid: this acid clumps milk proteins together making yoghurt.

5.5 understand the role of yeast in the production of beer

Yeast converts sugar to ethanol and CO2 whe it respires anaerobically.
ethanol is alcohol...

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

Pests can eat crops or damage them so they can't be sold.

Pesticides are used to kill pests that reduce crop yield.
The assure that crops won't be damaged. Fast and accurate to apply. Instant results.
They can harm other wildlife.
Killing the pest may affect biodiversity.
Pesticides can leech into the soil and possibly pollute rivers or surrounding habitats.
Pests can become immune.

Biological control is introducing a predator into the environment with the crops to kill the pests.
Cheep. Self regulating.
The predator may enter the wild and effect the biodiversity.

5.3 understand the use of fertiliser to increase crop yield

Fertilisers contain minerals that plants require to grow; most of them are called NPK fertilisers, this means they contain nitrates, phosphates and potassium.

Nitrates are needed to make proteins- proteins are what plant cells are made of. If there is a lot of nitrate in the soil then plants have the ability to grow as much as they can.

Phosphates are involved in respiration and growth- both things are needed to sustain a plant.

Potassium must be present for enzymes to work- with out it the plant wouldn't be able to carry out reactions and so would die or have very limited growth.

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

Glass houses and polythene tunnels increase the heat in the environment that crops are growing in. Reactions happen faster when there is more heat, for example photosynthesis. Given photosynthesis produces energy that the plant needs to grow, if there is more heat there is more growth and so higher yield.

Carbon dioxide is a reactant in photosynthesis. If there is a more than enough carbon dioxide, then every plant will be able to photosynthesise as best as it can. The more photosynthesis the more glucose, the more glucose the more energy, the more energy the more growth. Hence crop yield is increased.

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

In glasshouses and polythene tunnels conditions can be controlled. This control means that all the limiting factors for plant growth can be set to the optimum conditions; this will result in more growth, so higher yield.