B3 aqa

• The absorbtion of substances against a concentration gradient
• Uses energy- cells that use Active transport have a lot of mitochondria to provide the energy
• used widely in cells, plants uptaking mineral ions, salt glands in marine creatures

• lungs are in the upper area- thorax
• digestive system in the lower area- abdomen
• breathing system brings in oxygen-rich air and breaths out waste- CO2
• oxygen from the air difuses in to bloodstream and CO2 diffuses out
• lungs are adapted for efficiency- they have alvioli
• thin walls- short diffusion distance
• Moist surface- gases can dissolve
• Sperical shape- large surface area
• good blood suply- maintains concentration gradient

• molecules from food need to be made available for body cells
• as will provide energy for respiration
• move from small intestine into blood stream due to the concentration of food molecules in the gut
• the villi in the small intestine provide a large S.A. and have lots of capollaries
• well adapted to absorb products of digestion
• glucose moves into bloodstream via active transport
• Surface area : volume ratio is important
• - large S.A. is vital for successful diffusion

As with humans other organisms need to be efficient and have adaptations for gas and solute exchange. this depends on a large surface area, moist surfaces, short diffusion distances and a large concentration gradient

• Plants need CO2 and water for photosynthesis and they get CO2 by diffusion through the leaves
• thin leaves- small diffusion distance
• Air spaces- allows CO2 to come into contact with lots of cells
• stomata- allows plant to take in CO2 and controlls water loss.
• waxy cuticle also reduces water loss
• Most ions and water needed by the plant are uptakes through the roots (root hair cells increase the S.A)

• The loss of water in plants is called transpiration
• Stomata controlls water loss as they are opened and closed by guard cells
• Water is pulled up through the xylem from the roots to replace the water lost from the leaves in the transpiration stream
• Transpiration is more repid in hot, dry, windy or light conditions 

• the body transport system consists of blood vessels, the heart and the blood
• human beings have a double circulation
• the heart works as a pump moving blood around the body.
• the left side has more muscle as has to pump oxygenated blood around the body.
• Arteries- AWAY from the heart, think layer of muscle and elastic fibres
• Veins- TOWARDS the heart, large lumen, often have valves, thinner walls
• Capillaries- walls are one cell think- for diffusion of oxygen and sugar, tiny vessel with narrow lumen

• blood is the main transport medium in your body
• plasma transports dissolved food molecules, CO2 and urea
• your red blood cells (RBC) are adapted to carry oxygen from lungs to organs
• RBC are biconcave disks which have no nucleus and are packed with the red pigment heamoglobin
• RBC are just the right size to fit into capillaries.
• Oxygen is carried by heamoglobin which becomes oxyheamoglobin in a reversible reaction.

• energy from respiration allows muscles to contract
• for muscles to work constantly oxygen and glucose are needed faster
• CO2 has to be removed faster too
• during exercise your HR increases, breathing rate increases and the depth of breathing, the arteries to the muscles dilate and glycogen stores in the muscles are converted to glucose for fuel
• Regular exercise benifits muscles, heart and lungs
• Muscles get fatigued after lots of exercise and dont contract properly.
• without enough oxygen they will respire anaerobically- without oxygen
• Glucose is broken down into lactic acid, water and a small amount of energy
• after exercise oxygen has to break down the lactic acid
• the amount of oxygen is called the oxygen debt

• Kidneys filter the blood.
• All the sugar is actively reabsorbed and the mineral ions and water are selectively reabsorbed depending on what your body needs.
• Active reabsorbtion of sugar can take place against a concentration gradient
• Excess mineral ions and urea are removed in the urine
• Urea is produced in the liver

• People sufferng from kidney failure can be treated by dialysis or a transplant
• With dialysis your blood passes trough the machine which has the same concentration of the necesary components of the blood so they arent removed and enables urea and excess salt to be removed into the dialysis fluid
• disadvantage- follow carefully controlled diet and have regular long sessions
• however it is the difference between life and death so is useful to kidney failure patients.
• Kidney thransplants replace the damaged kidney and replaces it with a healthy kidney from a donor.
• Transplanted kidneys can be rejected by the body so to try and prevent this tissue types are matched as closely as possible.
• immunosuppressant drugs are used to supress the immune response.
• Disadvantage- high risk of rejection and taking medicine daily
• Advantage- can eat what you want and dont have to have dialysis.

• microbes are tiny living organisms like bacteria, viruses, fungi and protoctista
• they play a vital role in decay, recycling nutrients in the environment, they can cause disease and be usefull to us too.
• microorganisms can be grown in an agar culture medium with a carbohydrate energy source and various minerals and vitamins and proteins
• safety measures have to be taken and all equipment has to be serilised in order to grow uncontaminated cultures and avoid growth of harmful pathogens

• single-celled organism which can respire aerobically to produce CO2 and water.
• this is used in vread making to make the dough rise
• when it respires anaerobically it produces ethanol and CO2
• this is called fermentation
• Fermentation of yeast is used to produce ethanol in the production of beer and wine
• a sugar solution produced from barley being germinated is used as an energy source for the yeast in beer making. this is called malting
• Wine making uses natural sugars from the grapes as the energy source for the yeast.

• Bacteria are used in both yoghurt and cheese making
• Yoghurt- the process:
• starter culture of bacteria acts on warm milk
• lactose is converted to lactic acid in a lactic fermentation reaction
• this causes the milk to clot and solidify into yoghurt and the bacteria gives the yoghuet a smooth, thick texture
• Cheese- the process:
• a different started culture is added to warm milk giving a lactic fermentation which results in solid curds and whey.
• the curds are often mixed with other bacteria or moulds before they are left to ripen into cheese.

• microbes can be grown on a large scale in vessels called fermenters and make antibiotics and mycoprotein food
• They have special features to obtain the maximum yield of the product
• - an oxygen supply for the respiring microbes
• - a stirrer to keep the bacteria in suspention, maintain an even temp and ensure the oxygen is evenly spread throughout the culture
• - a water jacket to remove excess heat caused by microbes respiring
• - measuring instruments which constantly monitor factors like pH and temp changes

The fungus Fasarium is grown on sugar syrup in aerobic conditions to produce mycoproteins. It is a high-protein, low fat meat substitute so is good for vegetariens. it has a small taste of mushrooms and can have flavours added to it.

• the antibiotic Penicillin was discovered by Alexander Flemming
• the method of mass production was the work of Howard Florey and Ernst Chain
• Penicillin is made by growing the mould Penicillium in a fermenter
• the medium contains sugars and other nutrients and has a good supply of oxygen
• the mould only starts making penicillin after most the nutrients are used up.

• Biogas- mainly methane- can be produced by aerobic fermentation of a wide range of plant products and waste materials that contain carbohydrates
• Many different organisms are involved in the breaking down of material in biogas production
• All waste can be used and they contain the carbohydrates. not only can electricity be produced due to biogas, but the waste from the generators can be used as fertiliser.
• it is difficult to up scale but could be a very useful fuel for the future.

• Ethanol based fuels can be produced by the anaerobic fermentation of sugar cane juices and from glucose derived from maize starch by the action of the enzyme carbohydrase
• Maize (sweet corn) is a starch broken down into sugars which are then fermented to make ethanol.
• Sugar cane is fermented to produce ethanol. this process only has one step therefore is cheaper than using maize.
• using ethanol as a fuel is efficient, doesnt produce any harmful waste and is carbon neutral. the only problem is that it takes a lot of plant material to produce it.
• Ethanol is distilled from the fermentation products and can be used as a fuel in motor vehicles or mixed with petrol to make gasohol.
• to make ethanol production work financially long term, we need to find a way to use the waste cellulose