5.20 evaluate the potential for using cloned transgenic animals, for example to produce commercial quantities of human antibodies or organs for transplantation.

Advantages	Disadvantages
Animals that have beneficial products (e.g. cows with medicine in their milk can be cloned. Pigs with human hearts can be cloned for organ transplant). This means that the useful genetic characteristics  will always be passed on.	Some people believe that the cloned animals may not be as healthy as the normal ones
You can clone at anytime of the year – out of breeding season	Cloning is a new science. It may have consequences that we are not aware of.
You can clone infertile animals.	Difficult, time consuming and expensive.

5.16 understand that the term ‘transgenic’ means the transfer of genetic material from one species to a different species.

5.16 understand that the term ‘transgenic’ means the transfer of genetic 
material from one species to a different species. 
e.g.
Bacteria that contain the human gene for insulin

5.8 interpret and label a diagram of an industrial fermenter

*Substrate in = microorganisms in

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

Fermentation is where microorganisms break sugars down to release energy - usually by anaerobic respiration.
Production of yoghurt:

1. All equipment is sterilised to kill of any unwanted microorganisms
2. The milk is pasteurised at 72C for 15 seconds to kill of any unwanted microorganisms. The milks then cooled.
3. Lactobacillus bacteria are added and the mixture is heated to about 40C in a fermenter.
4. The bacteria ferment the lactose sugar to form lactic acid
5. Lactic acid causes the milk to clot and solidify into yoghurt
6. Flavours are added and it's packaged.

4.15 understand the biological consequences of pollution of water by sewage, including increases in the number of micro-organisms causing depletion of oxygen

Sewage contains lots of phosphates from detergents. It also contains lots of nitrates from urine and faeces.
These cause eutrophication in the same way that fertilisers do.

4.10 describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, decomposers, nitrifying bacteria and denitrifying bacteria (specific names of bacteria are not required).

• Nitrogen fixing bacteria - these fix the N2 in the air into useful nitrogen compounds which the plants can use. 
• Nitrifying bacteria - these turn ammonia in decaying matter into nitrates.
• Decomposers - these break down proteins and urea (from decaying matter and faeces) into ammonia.
• Denitrifying bacteria - these convert nitrates back into N2 gas. These are of no use to us.

4.8 describe the stages in the water cycle, including evaporation, transpiration, condensation and precipitation

3.33 understand that the incidence of mutations can be increased by exposure to ionising radiation (for example gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (for example chemicals in tobacco).

The chance of random mutations occuring can be increased by exposure to:

1. Ionising radiation
2. Chemicals (mutagens)

3.17 understand the meaning of the term: codominance

Neither allele is recessive so you show characteristics from both alleles.
e.g.
Red codominant allele is mixed with a white codominant allele
Result = pink allele

3.11 understand how the developing embryo is protected by amniotic fluid

The amnion membrane - which contains the amniotic fluid - protects the embryo from any bumps.

3.10 describe the role of the placenta in the nutrition of the developing embryo

The placenta lets the blood of the embryo and mother get very close. This means any vital nutrition the embryo needs is given to it by the mother without their blood ever touching.
Also the waste products are given to the mother from the baby through the placenta.

3.6 understand how germinating seeds utilise food reserves until the seedling can carry out photosynthesis

A developed seed contains:

1. A food store
2. An embryo
3. Hard seed coat

When it starts to germinate (has the right conditions) it gets glucose for respiration from it's own food store. This gives it energy to grow.

Once the plant has grown enough it doesn't have to rely on the food stores as it can use photosynthesis.

3.5 understand the conditions needed for seed germination

Seeds need at least three things for germination:

1. Water - to activate the enzymes to break down the seeds food reserves
2. Oxygen - for respiration which gives energy for growth
3. A suitable temperature - for the enzymes to work (this depends on the seed)

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

Skin in Homeostasis

Sweating

When you get too hot, sweat is produced and lays on your skin. It is heated by the body and when it evaporates it takes the energy from the body with it. It takes your body's heat energy thus cooling your body down.

Vasoconstriction & vasodilation

When it's your too hot:

Blood vessels near the surface of the skin widen - vasodilate - which allows more blood to flow near the surface of the skin. This allows more heat to radiate out of the blood to the environment.

When it's too cold:
Blood vessels near the surface of the skin constrict - vasoconstrict - so less heat can be radiated to the surroundings.

NB: Two more useful points - 
When you're too hot:
Hairs lie flat

When you're too cold:
You shiver which generates heat in the muscles
Hairs stand on end which traps an insulating layer of air above your skin

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

The Iris Reflex

When you're exposed to bright light it triggers a reflex that makes the pupil smaller. The circular muscle in the iris contracts making the pupil smaller.
In dim light the iris adjusts to let more light in by increasing in size. The radial muscles contract pulling the iris back and making the pupils bigger.

Focusing

Click here for eye diagram.

When the eye focuses by changing the shape of the lens it's called accommodation.

Looking at distant objects:

The ciliary muscle relaxes and allows the suspensory ligaments to pull tight. This makes the lens thin.

Looking at close objects:

The ciliary muscles contract which slackens the suspensory ligaments. The lens becomes more curved.

2.62 understand that platelets are involved in blood clotting, which prevents blood loss and the entry of micro-organisms

Platelets

Platelets are small fragments of cells that can help the blood to colt

When you get a cut these platelets clump together to stop you losing too much blood. These are called blood clots. These do two things:

1. Stops blood loss
2. Prevents micro-organisms entering the blood stream.

In a clot the platelets are held together by a protein called fibrin. 

Clotting requires other things called clotting factors to work. 

2.61 understand that vaccination results in the manufacture of memory cells, which enable future antibody production to the pathogen to occur sooner, faster and in greater quantity

Vaccination

In the time it takes your body to make antibodies for an active pathogen it can make you very ill or even kill you. To avoid this you can be vaccinated:

1. An inactive pathogen is injected into the body. These still have the antigens of the pathogen so trigger an immune response.
2. Your lymphocytes produce antibodies to attack them. 
3. Some of these lymphocytes, which are now specific to the pathogen, will now remain in your system forever. These are called memory cells. 
4. If the pathogen is ever recognized again then the antibodies will be released quickly and in great numbers so the immune response is much faster. 

2.51 describe the role of phloem in transporting sucrose and amino acids between the leaves and other parts of the plant

Phloem Tubes

These are cells with porous end cell walls which transport 'food' around the plant.

• The phloem transports food like sucrose and amino acids from the leaves to the rest of the plant. 
• This movement of food substances around the plant is called translocation.

2.43 describe experiments to investigate the effect of light on net gas exchange from a leaf, using hydrogen-carbonate indicator

Experiment

Hydro-carbonate indicator:

Normal CO2 = Orange

Increased CO2 = Yellow

Decreased CO2 = Purple

1. Take 4 test tubes and put add the same volume of hydro-carbonate indicator to each of them
2. Then take 3 similar sized leaves, roll them up and trap the leaf stem with the bung so they're sitting above the indicator
3. Wrap aluminium around 1, baking paper and leave the 3rd. 
4. Place them in bright light and leave them for an hour. Then check the colour of the indicator

The 4th tube is the control. If the indicator changes in that one there is something wrong with the experiment.

2.40 understand that respiration continues during the day and night, but that the net exchange of carbon dioxide and oxygen depends on the intensity of light

REMEMBER

Respiration is constant. It continues at the same level during day and night.

Photosynthesis varies depending on light intensity

Click here to see this on a graph.

This means that the net exchange of carbon dioxide and oxygen varies aswell.

If there is less photosynthesis it means that there will be less intake of CO2 and less production of oxygen. This means more CO2

If there is more photosynthesis it means there will be more intake of CO2 but more production of oxygen. This means more oxygen.

So... 

If the light intensity is greater (e.g. day) then there will be more CO2 intake and vice versa.