5.9 - Fish Farming

Fish are an attractive product to farmers as they: 
- have low fat and high protein 
- are efficient at turning their nutrient into fish mass 


Fish Farming Advantages: 
- allow the control of the quality of water - clean 
- can control predators 
- Can produce and control pests 
- Can control diseases 
By controlling all these factors it contributes to an increase in yield of fish. 


However, where there is a high density of fish, the possibility of transmission of disease increases. 
- This has caused fish farmers to begin using antibiotics
- The abundance of fish within the fish farm makes pests common and so some farmers have begun to use pesticides 


Both these contribute to the cause of concern for humans.  

5.8 - Fermentation

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 microorganisms

5.7 - Lactobacillus in Yoghurt

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

5.6 - Carbon Dioxide Production

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

5.5 - Beer Production

- yeast in beer production 
beer is made of : 
starch --- Amylase (germination of seed - known as 'malting') ----> Maltose ---Maltase---> Glucose 


Starch comes from: 
- Barley Seeds 
- Wheat Seeds 
- Rice (asian beers) 


Glucose comes from Starch 


Glucose --anaerobic respiration (yeast supplies enzymes for conversion) ----> ethanol + CO2 + Hops 


Hops flavors the beer (in plants)  

5.4 - Pesticides and Biological Control

- Large fields of crops all at the same time - Monoculture 
- Monoculture - very susceptible to pests - they use the crop as a food source - this reduces the productivity of farming (food and financially)


1. Pesticides - chemicals - designed to kill the pest 


Advantages: 
- Chemicals - easy to obtain  
- Easy to apply - spray 
- Very effective 


Disadvantages: 
- Toxic - may kill other plants and animals other then the pests and may be harmful to humans 
- Bio accumulation - pesticide builds up through the food chain causing problems for higher trophic levels (DDT) 
- Mutation in the pest leads to resistance - pesticide must then be applied at higher concentrations which then make it more toxic





2. Biological Control 
Example in Australia 

Advantages: 
- No toxic chemicals involved 
- Less impact on man/wildlife 


Disadvantages: 
- Not 100% effective 
- Difficult to control - always a danger that the introduced species will find an alternative prey. e.g. Cane toad (australia) 
-  Difficult to match a predator to the prey. May not be able to find an animal that can remove the pest

5.3 - Fertilizers

- achieved in farming by fertilizers in soil - these take the form of nitrates or phosphates (can be a combination of both) 
- go down into the soil and are take up by the root structure - go up to the leaf and is then used for the construction of: 
nitrates --> proteins
phosphates --> DNA and membrane structure 


Fertilizers can be split into two groups 
Organic and Artificial 

Organic: 
- produced from animal waste on farms, cow faces --> collected by the farmer and goes through decomposition and fermentation and forms slurry (gives nitrate and phosphate to promote growth) 


Artificial: 
- Chemicals which are produced. Such as Potassium nitrate and ammonium nitrate --> go into solution in the soil water --> release nitrate and promotes growth like an organic fertilizer 

Eutrophication - problem which arises through the use of artificial fertilizers 

5.2 - Crop Yield

Related to the: 


rate of photosynthesis - this is the combination of CO2 and water with light (enzyme) to form glucose (starch) and oxygen 
- Increasing the concentration of CO2, CO2 is the substrate 
- Shown in graph - rate of ps will increase the yield until the greatest yield point 

Temperature - Increasing 
- Shown in graph - rate of ps increases as temperature increase up to an optimum (peak)  temperature 


Increasing temperature in a greenhouse can also avoid frost damage and provide constant temperature - both contribute to increase in yield 

Both have limits (optimums) 

5.1 - increasing yield

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

In a greenhouse you can control factors such as heat moisture, you can set these factors to best suit a particular crop. This optimization of environmental variables should result in a better yield of a particular crop. 

• Protect the crops from the environment 
• Temperature 
• Water levels
• Fertilizers 
• Carbon Dioxide levels
• all controlled to maximise yield

Blue - sensory nerve 
blue circle - dorsal root ganglion - where you find the body of the sensory nerve 


Red - Motor nerve 
the red triangle -  where you find the body of the motor nerve 


grey matter (dog bone shape) 
White matter (everything else) 

2.89 - Hormones

2.89 understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and estrogen.

The hormonal system also coordinates the body. Hormones are chemicals produced by glands. Small amounts of these chemicals are carried around the body in the blood. They tell different parts of the body what to do and then body responds to these hormones. 


Hormones are involved in homeostasis. Hormonal glands are affected by feedback. If the level of hormones in the blood is too high, the glands detects it and makes less hormone. If the level of hormones in the blood is too low, the gland detects it and produces less hormone. 

2.88 - Skin temperature regulation

2.88 describe the role of the skin in temperature regulation, with reference to sweating vasoconstriction and vasodilation

A section of the skin 

We are warm blooded. This means that we can keep our body temperature constant all the time. 
Warm blooded animals have fur or hair which traps a layer of air close to the skin. Air is a poor conductor of heat so it cuts down the amount of heat lost. 


In cold weather the hairs stand up. They do this when the hair muscles contract, this traps a thicker later of air so it cuts down even more on the heat loss. 
In hot weather the hair lies flat. The hair muscles are now relaxing so less air is trapped close to the skin and more heat is lost by radiation. 

 Your body temperature is monitored by your brain, it monitors it by the blood running through it. 


When it is hot: 
Blood Vessels at your skin surface widen. They allow more blood to flow to the surface. So more hear is lost by radiation. 
Sweat Glands in your skin make sweat. The sweat evaporates and this cools you down.


When it is cold: 
Blood Vessels at your skin surface close up. They cut down the flow of blood to the surface. So less hear is lost by radiation.  
Sweat Glands stop making sweat 
Shivering, your muscles start to contract quickly. This produces extra heat that warms your body. 

Vasodilation: The dilatation of blood vessels, which decreases blood pressure.

Vasoconstriction: The constriction of blood vessels, which increases blood pressure.

2.87 - Focusing

2.87 understand the function of the eye in focusing near and distant objects, and in responding to changes in light intensity


- Most of the bending of the light rays is done by the curved cornea, but your lens can bend the light rays slightly. 
- The shape of the lens is controlled by the ciliary muscles. 


If you are looking at a distant object: 
- The ciliary muscles relax
- this tightens the suspensory ligaments 
- so the lens is pulled into a thin shape 
- the distant object is focused on the retina 


If you are looking at a near object: 
- the ciliary muscles contract
- this slackens the suspensory ligaments
- so the elastic lens goes flatter 
- The near object is focused on the retina 

2.86 - The Eye

2.86 describe the structure and function of the eye as a receptor
The eye is a receptor that responds to light.
Light enters your eye through the transparent cornea, it passes through the lens and is focused on the retina. 
In the retina there are cells which are sensitive to light called rods and cones. 
When light stimulates them, they send impulses to the brain along the optic nerve, 
Your brain then interprets these impulses to make a picture. 


The image on the retina is inverted but the brain has learned to turn the picture the right way up. 
In the retina the rod cells respond to dim light and cone cells detect color and details.