B3 Revision

Osmosis is the movement of water from a high water concentration (dilute solution) to a low water concentration (concentrated solution) through a partially permeable membrane.

Requires energy from the cell, which is created by respiration. During active transport, carrier proteins in the cell membrane ‘pick up’ particles and move them against the concentration gradient. Requires energy from the cell, which is created by respiration.

Ventilation is the process of breathing in and breathing out Feature Inhaling Exhaling Diaphragm flat & contracted domed & relaxed Volume increases decreases Ribs up and out down and in Intercostal muscle contracted relaxed Pressure Lungs inflated deflated

Stomata - water Guard cells – sensitive to water and light. TOO MUCH water – guard cells FULL, PLUMP, (TURGID)  stomata OPEN for gas exchange TOO LITTLE water – guard cells not much water, (FLACCID),  stomata CLOSE to prevent water evaporation. Increase in light intensity opens stomata Decrease in light intensity closes stomata

Transpiration is the Evaporation of Water from Leaves

Light - more light = more photosynthesis = more co2 released through stomata = more H2O lost through stomata = increased transpiration Temperature - More heat = more evaporation = increased transpiration Humidity - A lot of water vapour in air = less water loss as air already saturated with air = decreased transpiration Wind - Water vapour in air is replaced with drier air = water concentration in air is lower than in plant = increased transpiration

aorta pulmonary artery pulmonary vein valve left atrium valve oxygenated blood to the body pulmonary artery pulmonary vein valve left atrium valve vena cava tendon right atrium left ventricle valve right ventricle

A blood vessel which transports blood away from the heart A blood vessel which transports blood back to the heart A permeable blood vessel where gas exchange takes place Red blood cell not carrying any oxygen Red blood cell carrying oxygen Carries deoxygenated blood from the heart to the lungs Carries oxygenated blood from the lungs to the heart The main blood vessel transporting deoxygenated blood to the heart The main blood vessel transporting oxygenated blood to the body Found in the heart and veins to ensure the blood flows in one direction

Artificial Heart Mechanical device to pump blood ADVANTAGES Temporary fix until donor heart is found Some cases permanent therefore no need for transplant Not rejected by body’s immune system DISADVANTAGES Surgery involved therefore risk of infection Don’t work as well as natural Can wear out Blood flow is not as smooth therefore could get clots Drugs to thin blood

Stents are metal grids which can be inserted into an artery to maintain blood flow by keeping the artery open.

Advantages & disadvantages of stents No anaesthetic Relatively cheap Stent does not corrode Disadvantages Cannot open the most blocked or narrowed arteries Can irritate the lining of the blood vessel causing scar tissue to be formed Need to take anti-coagulant drugs

air sac in the lung 2 Haemoglobin and oxygen join to make oxyhaemoglobin oxygen 3 when the blood flows past cells with very little oxygen in them the oxyhaemoglobin breaks down 1 as blood flows through the lungs the haemoglobin in the red cells picks up oxygen 4 the haemoglobin in the red cells goes back to the lungs to pick up more oxygen oxygen diffuses into the cells of the body oxygen is used for respiration

Artificial blood products Advantages Disadvantages Cheap Sides effects Easily available Difficult to get in to the system Don’t need to depend on donors May rely on blood products anyway Good carriage of oxygen (compared to plasma or saline) Broken down rapidly No risk of disease Don’t carry dissolved food Long shelf life Don’t clot blood Less religious objections Don’t offer defence against disease

Kidney Function Summary 1 - Filter the blood at high pressure (squeeze everything into the kidney tubule [except proteins, blood cells]) 2 – Reabsorb all the glucose and amino acids by active transport 3 – reabsorb the dissolved ions (as much as the body needs) 4 – reabsorb as much water as the body needs 5 – release the urea, excess ions and excess water as urine.

Blood leaves the artery and enters the dialysis machine where the blood flows between partially permeable membranes. The dialysis fluid contains the same concentration of useful substances as the blood. Dialysis fluid contains no urea at all so urea passes out from the blood into the dialysis fluid due to a steep concentration gradient Blood with correct conc of dissolved substances is returned

Donor rejection All your body cells have ANTIGENS (labels to say you are you!) The donor kidney will have DIFFERENT ANTIGENS The immune system of the person who receives the kidney could ATTACK the donor kidney. TISSUE TYPE the kidney so its as close a match as possible Immunosuppressant drugs given for life to reduce chance of rejection

Glucose – a sugar found in the body. Glycogen – a storage of carbohydrate found in liver and muscles Glucagon – converts glycogen into glucose. Insulin – converts excess glucose into glycogen for storage

Evaluate the use of insulin injections over pancreas transplants Insulin treatment widely available; relatively cheap Pancreatic transplant good but surgery required; high risk; expensive; long term immunosuppressant use and most importantly not enough donors;

Compare modern insulin treatment with the original insulin used to treat diabetics and evaluate the two treatments Original – from pancreases of cattle and pigs used for meat ; no control over quantities as used what was available from slaughterhouses; not genetically identical to human insulin. Some people disagree with using animal insulin (ethical/religious issues) Modern – produced by genetically modified bacteria; exact quantity and quality control; genetically identical, however some people disagree with GM insulin, long term effects unknown

Increased population Non-renewable energy resources (such as coal, oil and natural gas) are being used up rapidly. More land is being used for buildings and transport networks, quarrying, farming and dumping waste - reducing the amount of land available to other animals and plants. More waste is being produced - causing more pollution.

Pollution Human activities may pollute: Water Air Land with sewage and fertilisers (eutrophication) or toxic chemicals Air with smoke and gases such as sulfur dioxide which contribute to acid rain Land with toxic chemicals such as pesticides and herbicides, which maybe washed from the land into water

Deforestation Is the cutting down of large scale forests, especially in tropical areas. Occurs because land needed for growing biofuel crops, growing food crops (rice) and rearing cattle, buildings, wood used for timber (furniture etc…) Causes damage because releases of CO2 when burned, less CO2 is locked away as wood, reduced biodiversity, loss of homes of indigenous people, increased methane release from rice and cattle fields.

Ethanol can be made by a process called fermentation Ethanol can be made by a process called fermentation. This converts sugar into ethanol and carbon dioxide if conditions are anaerobic. Disadvantages Greater demand on rainforest land. Only grows well in hot countries Engine modification is needed Although biofuels are in theory carbon neutral, this does not take into account the carbon dioxide emissions associated with growing, harvesting and transporting the crops, or producing the ethanol from them

Efficiency of food production can be improved by reducing the number of levels in the food chain

Animals are kept still and warm so they transfer less energy as waste heat. The energy saved can be used to produce more meat, eggs or milk.

FOOD MILES = The distance our food travels to get to our homes Why do we import food from abroad What are the problems associated with this How can we reduce food miles Cheaper, want out of season food, bigger profits for supermarkets, some food cannot be grown in UK Increased fuel consumption = increased CO2 emissions = global warming Buy British food, buy food locally, grow own food

Fishing quotas Size of the holes in nets, so only bigger fish are caught. Bans on fishing during breeding season. Strict limit on the amount and type of fish caught.

What is mycoprotein? What conditions are needed for its optimum growth? Why is this a good food source? Substance made from the fungi Fusarium Aerobic conditions High protein and low fat meat substitute ideal for vegetarians and dieters