Xelronia

AQA A2 Physics Unit 4 definitions

noreply@blogger.com (Alex) — Fri, 31 May 2013 09:34:00 +0000

Newton's Second Law – The rate of change of momentum is directly proportional to the resultant force upon it
Newton – The unit of force where one kilogram will be accelerated one metre per second
Conservation of momentum – In a collision, in the absence of external forces the total momentum remains constant
Impulse – change of momentum
Elastic collision – no momentum or KE is lost
Inelastic collision – momentum is conserved but KE is lost
Totally inelastic collision – momentum is conserved but KE is gained
Cantripetal force – the force, acting towards the centre of the circle and perpendicular to the motion of an object, responsible for the circular motion of that object
Simple harmonic motion – Motion where the acceleration of an object is proportional to its displacement from a central point and directed towards the mid point
Damping – loss of energy from an oscillating system leading to a reduction of amplitude of oscillation
Resonance – the situation which occurs when the driving force of a forced oscillation has the same frequency as the natural frequency of the material
Gravitational Field Strength – the force acting on a 1kg unit mass at any point in a gravitational field
Newton's Law of Gravitation – the force of attraction between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
Gravitational potential – The work done against the field in moving a unit mass from infinity to its current point
Electrical field strength – the force acting on a +1C charge at a point in an electric field
Electric potential – the work done against the field in moving a +1C charge from infinity to its current point
Capacitance – the amount of charge stored by a capacitor per volt PD across the capacitor
Magnetic field strength – the force on 1m of wire carrying a current of 1A at right angles to the magnetic field
Flux density – amount of flux (unit Wb) in an area (unit m^2) (total unit Wb m^-2 = T)
Flux linkage – amount of flux in an entire coil
Faraday's law – the emf produced by movement of a coil is directly proportional to the rate of change of flux passing through the coil
Lenz's law – the induced emf produced by movement of a coil always acts in the direction that opposes the force which made it

Edexcel A2 Chemistry Unit 4

noreply@blogger.com (Alex) — Thu, 30 May 2013 13:54:00 +0000

Rates of Reactions

Rate = k[A][B]
Observed by measuring the change in some physical quantity over time
- Eg. Charge, colour, pH
Orders of rates depend on the relative effect each reagent's concentration has on the overall rate
Main example is propanone and iodine
- First order in respect to propanone
- First order in respect to H+
- Zero order in respect to iodine
  - Unexpected because iodine present in the reaction but not in rate equation
  - Zero order means the reagent is involved in a fast step of the reaction which is not rate determining
By looking at the rate equation, we can see what reagents are in the rate determining step, as all reagents involved in the rate equation must be in the rate determining step of the reaction

Halogenoalkanes

Reaction by nucleophillic substitution to form alcohols
Reagent is NaOH
Heated under reflux
SN1
- Tertiary halogenoalkanes
- Halogen attracts electrons from the C-X bond, therefore breaking the bond
- Forms carbocation plus halogen ion
- Only halogenoalkane in rate determining step
- OH group attracted to C+ so alcohol forms
SN2
- Primary halogenoalkanes
- OH group attracted to slight positive charge on central carbon due to polarity of C-X bond
- 5 co-ordinate transition state
- OH group pushes halogen ion away

Activation energy/catalysts

Activation energy is the energy needed for a reaction to occur
Higher activation energy means there is a lower rate as less particles have enough energy
Catalysts decrease activation energy required and so increase the rate
Homogeneous catalysts are in the same phase as the reactants
Heterogeneous catalysts are in a different phase to the reactants
- Work by allowing the reactants to adsorb to the surface of the catalyst
- Bonding with the catalyst allows the reactants' bonds to be broken more easily so the reaction happens faster
- Also concentrates the reactant in a small area so there is more chance of collision
- The part of the reactant molecule which will react will be properly oriented for the reaction to occur
- The product molecules then desorb

Entropy

Measure of how much disorder there is in a substance
0 at 0K in a perfect solid crystal
Energetically more stable the greater the disorder is hence why gases diffuse out
If total entropy is positive a reaction is spontaneous and therefore feasible, otherwise no reaction
Total entropy = RlnK
- R = gas constant
- lnK = natural log of equilibrium constant
  - This is why equilibrium constants change with temperature
Thermodynamically stable when entropy is less than 0 for a reaction
Kinetically inert when entropy is positive but temperature does not give a fast rate due to a high activation energy
Lattice enthalpies
- Not sure why they're in this section but:
- Greater charge/smaller ionic radius = larger charge density
- Larger charge density = stronger force of attraction between ions in the lattice
- Stronger bonds = more exothermic (making bonds is exothermic)
- More exothermic = more negative lattice enthalpy

Equilibria

Dynamic equilibrium is when the rate of the forward and reverse reaction are equal
At a certain temperature, one particular ratio of products to reactants will always be reached
- Therefore products/reactants = constant
  - This constant is the equilibrium constant
    - It doesn't change unless you change the temperature
  - Changing the concentration of products/reactants by removing/adding substances will cause more or less of the products and reactants to be products to maintain the equilibrium at the same point
Acid base equilibria
- Strong acids dissociate fully
- Weak acids will not fully lose all of their protons
  - This is an equilibrium between protonated and deprotonated forms
  - The constant is Ka
- Water is a special case
  - As the concentration of water is so high in any calculation, we take it as 1
  - Therefore Ka for water = [H+] [OH-]
    - This has the special name Kw
    - Value 1*10^14 mol^2 dm^-6
  - This can be used to calculate the pH of alkaline solutions
- pH = -log[H+]
- In most calculations [H+] = [OH-]
  - So write it as H+ squared
- pH curves are drawn by sketching a graph of pH as you add an acid/alkali to a volume of acid/alkali
  - Mark on the known points eg. Equivalence points, pH with no alkali etc.
  - Sketch the rest according to whether it's a strong base/weak base strong acid/weak acid
  - At half the equivalence point, pKa = pH
- Indicators should be picked so that they have their pKa in the middle of the steep region of the pH curve
- Buffers
  - Resist changes in pH
  - Made from weak acids/bases and their salts
  - Some pH change still happens but mostly the H+ concentration is kept constant as the buffer salt/bases will react

Organic

Isomerism
- Optical isomerism
  - Caused by carbons with 4 different groups attached
  - Creates two possible shapes which are non-superimposable mirror images of each other
  - Distinguished by testing to see if they will rotate the plane of plane polarised light left or right
- Geometric isomerism
  - E/Z or Cis/trans
    - Z for zimilar
  - Caused by the restricted rotation of groups around a C=C double bond
    - Or in a cyclic group
Aldehydes and ketones
- Lower boiling point than alcohols and limited solubility
- This is because while the carbonyl oxygen can form hydrogen bonds using its lone pair, it has no hydrogens that are polarised enough to form bonds
- In alcohols the hydrogen in the hydroxyl group can be used to form hydrogen bonds as well as the oxygen using its lone pair
Nucleophillic addition using HCN
- HCN and NaOH or KCN and sulphuric acid
- Carbon in CN has a lone pair and attacks the positive side of the polar C=O bond
- Electrons from bond given to carbonyl oxygen
- Carbonyl oxygen then give electrons to H-CN to regenerate CN- nucleophile
Chemical tests
- Brady's/2,4-DNPH – aldehyde or ketone
- Tollen's reagent/Benedict's reagents – aldehyde
- Iodine + NaOH – Iodoform, methyl ketone
- Oxidation – Potassium dichromate (VI)
  - Orange to green
  - Manganate (VII) can also be used (purple to colourless)
- Calcium carbonate – carboxylic acid
Reduction
- Lithium aluminium hydride in dry ether
- Carboxylic acid to alcohol/aldehyde, ketone to alcohol, aldehyde to alcohol
Hydrolysis of nitriles
- Nitrile refluxed with HCl
- Forms carboxylic acid
Formation of esters
- Carboxylic acid + Alcohol
- Reflux under dilute acidic conditions
- Distil the ester and neutralise
- Alternatively form by reacting acyl chloride with alcohol to give a greater yield as it goes to completion
Acyl chlorides
- Formed by reacting carboxylic acids with PCl5
- React with water to form carboxylic acid
- React with alcohol to form ester
- React with amines/ammonia to form amides (N substituted)
Reactions of esters
- Acid hydrolysis – reverse of making
- Base hydrolysis – reflux with dilute NaOH to form a salt and alcohol
  - Used to break down triglycerides to glycerol + soaps
  - Soponification is this
- Trans-esterification
  - Ester + Alcohol -> New ester + alcohol (refluxed, acidic)

Spectroscopy

Mass spec
NMR
- Low-res just measures number of hydrogens in each environment
- High-res measures spin-spin coupling so follow n+1 rule to determine how many sub peaks each peak will be split into
IR
- Bonds absortb IR radiation and so dips in the spectrum can be seen
- Known fingerprint region can be used to positively identify a chemical else the bonds in the functional groups will be used to identify functional groups
Best to use data from multiple sources to confirm information
Chromotography
- Change in retention time/movement of a substance depending on the force of attraction between it and the stationary phase
- Gas chromatography
  - Stationary phase is a tube of oil
  - Vaporised sample is pumped through tube, depending on force between the sample and oil the retention time will be longer or shorter
  - Compare to a library of known retention times to identify sample
- High performance liquid chromatography
  - Stationary phase is a tube of silica pellets
  - Tube not heated, pressure used to force sample through
  - Can be used if heat sensitive sample

AQA A2 Physics Unit 4

noreply@blogger.com (Alex) — Wed, 29 May 2013 16:07:00 +0000

Further Mechanics

Momentum
- Momentum is always conserved in any collision
- Kinetic energy, however, can be transferred into/from other forms in collisions
  - Elastic collisions are ones where KE is conserved
  - Inelastic collisions are ones where KE is not conserved
  - Totally inelastic collisions are ones where the two object stick together
- Impulse is the change in momentum
  - Force * Time
- Unit is Ns (newton-seconds)
Circular motion
- Linear velocity is the usual distance/time
  - This means it's the proportion of the circumference of the circle moved through in a second
- Angular velocity is the angle moved/time
  - Angle in radians so 2*pi radians in a circle
- Centripetal force is a constant force which acts perpendicular to the movement of the object towards the centre of the circle
Simple harmonic motion
- Motion where the acceleration of the object is proportional to its displacement from the equilibrium position, and that acceleration always acts towards the equilibrium position
- Amplitude = maximum displacement from equilibrium position
- In the formulas for SHM, T = 0 when x = max and then increments from there
- KE is max when displacement = 0
- Potential energy is max when displacement = max
- Damping
  - Means the amplitude decreases as KE is lost
  - Time period of oscillations does not change
  - Critical damping is the amount of damping which causes the system to return to equilibrium quickest
  - Overdamping will lead to it taking longer to return to equilibrium
- Natural frequency and resonance
  - When objects are allowed to oscillate of their own accord they will at the natural frequency
  - When objects are forced to oscillate, any damping felt will decrease around the natural frequency
    - This means that the amplitude increases closer to the natural frequency

Gravitation

Newton's law of gravitation
- The force due to gravity felt by two masses is proportional to the sizes of the two masses and inversely proportional to the square of the distance between them
Field strength = force felt by a test mass
On diagrams the arrows point in the direction the test mass would go
Potential
- Work done against the field to bring an object from infinity to that point
- As the field is doing the work, negative value
- Gradient of a potential/distance graph is field strength
Orbits
- Gravity acting as centripetal force
- Circular orbits have constant speed and distance from earth
- Elliptical orbits have higher speeds as they are closer to earth, and slower speeds further away, meaning KE + GPE remains constant
- Geosynchronous orbits take 24 hours

Electric Fields

Coulomb's law
- The force between point charges is proportional to the size of the charges and inversely proportional to the square of the distance between them
Field strength = force felt by +1C charge
On diagrams the arrows show the direction a positive charge would move
Parallel plates of opposite charge will have straight field lines, creating an area of uniform field strength
Potential
- Work done against the field moving a charge from infinity to that point
- For positive charges this is positive, as work must be done as positive charges will be repelled
- Negative charges this is negative as the field will be doing the work
Charged particles moving through electric fields will have a parabolic path
Capacitors
- Capacitors charge quickly at first and then more slowly
- This is all given by the equation involving natural logs
- T = RC (time taken for charge to drop to 37% or rise to 63%)

Magnetic fields

Force = Flux Density * Current * Length
Flux density is the measure of how many lines of flux there are in an area
This all depends on the force, current and magnetic field being at right angles according to the left hand rule
Flux and flux linkage
- Flux is measured in Wb
- Flux linkage is the total flux in an entire coil, so number of turns * flux
- When the coil is not perpendicular to the field, multiply the flux/flux linkage by cos(angle) where the angle is drawn from a normal perpendicular to the side of the coil compared to the direction of the magnetic field
  - Basically, draw it so the angle is 0 when the coil is perpendicular to the field and you know it's right because cos(0) = 1 and so that's when the flux linkage will be highest
Electromagnetic induction
- Faraday's law
  - The induced EMF is directly proportional to the rate of change of flux linkage
- Lenz's law
  - The induced EMF is always in the direction that will oppose the force that created it
- Relative motion between a conductor and a magnet will create an EMF in the conductor, as the electrons in the conductor feel a force from the magnetic field and so become concentrated in one part of the conductor
Transformers
- Made from two coils with a core of soft iron
- The AC in one coil means that the flux produced is always changing, so there is an EMF induced in the second coil as there is a relative change in flux linkage
- The ratio of the voltages is the same as the ratio of turns on either coil
- Generally highly efficient
  - Some losses due to eddy currents induced in the core
    - (reduced by laminating the core)
  - Some losses due to changing the polarity of the core

AQA A2 Biology – Unit 4

noreply@blogger.com (Alex) — Mon, 27 May 2013 09:21:00 +0000

Ecology and biochemistry, because they go together right?

Ecology

Study of living organisms and environment
Terms
- Ecosystems – self contained area containing living organisms linked together by nutrient and energy flow
- Habitats are abiotic part of organism
- Community is the term for all organisms of all species in an ecosystem
- Population is for all organisms in one species
Fieldwork
- Sampling
  - Random sampling – measuring tapes placed along sides like axes of graph and random numbers are used to determine co-ordinates for a quadrat where you count the species present.
    - Preferable 2% area coverage
    - Keep sampling until means remain constant so sample is representative
  - Systemetric sampling - choosing where to take samples to investigate a pattern
    - Basically, belt transects
    - Count the organisms in a quadrat placed at regular intervals along the line to investigate how samples change
  - While sampling measure abiotic factors to understand how visible differences in the ecosystem affect the local conditions
    - Soil temp
    - Light intensity at ground level
    - Soil pH
    - Soil depth
    - Altitude
    - Water flow rate
    - Water oxygen content
      - And many more...
  - Repeats for reliability, over long time periods to account for daily and seasonal variations
  - Pick your quadrat so you identify as many species as possible without wasting effort
    - Point quadrats can be used as a more accurate and less subjective measure of percentage cover
  - Quadrats are good for plants and slow animals, but otherwise use nets or traps
- Capture-Mark-Release
  - Method of estimating the population of a species in an area (only to within 50%)
  - Capture a large number of animals, then mark them
    - Eg. Leg rings on birds
    - DNA fingerprinting can also be used
  - Release the animals so they mix with the general population
  - Capture more animals
  - The proportion of captured animals that are already marked is can be used to work out the total number of animals in the area
    - N = Sample size ^2 / Recaptures
  - Limitations
    - Marking cannot affect survival
    - There must be time for the marked animals to mix with the population
    - The population must be constant
- Stats tests
  - GCSE stats in action
  - Key thing is that we want a 95% confidence value before we reject the null hypothesis
    - This means error bars representing 2SD must not overlap on a bar chart else we cannot assume there is a difference between the two values in reality
  - Qualitative data can be compared to expected values for frequency (eg from genotype calculations)
Populations
- Affected by abiotic factors – density independent as they will limit growth regardless of competition - usually harsh environments
- Also affected by biotic factors – these often lead to competition – usually milder temperate climates
  - Interspecific – between species
  - Intraspecific – within a species
    - Significant as they have the same niche and so are after the exact same resources
    - Stabilises population as population growth increases competition, leading to population decrease, decreasing competition and so on
    - Leads to natural selection as individuals within a species with better suited genes will be more likely to survive competition and pass those genes on
- Predation
  - When one species uses another species as food
  - As prey increases in population size, competition in predators reduces
  - Predator population growth results in more prey being eaten so numbers reduces
  - More predator completion so predator numbers decrease
  - Prey numbers then recover and cycle restarts
- Parasitism
  - Not in the book but ok
  - Parasites kill their hosts, so as parasite numbers increase host numbers decrease
  - Parasites then die due to lack of hosts
  - Hosts then increase again in number as there are less parasites killing them off
  - Cycle restarts
- Each population has a niche, which is the conditions it is best adapted to surviving
  - Populations can coexist when they have different niches, but not when their niches are too similar that one species is able to outcompete the other
  - Specialists are species with a narrow niche that outcompete any other species attempting to occupy the niche
Succession
- The idea that ecosystems change over time
- It's self-perpetuating because the growth of organisms in an ecosystem changes the environment and so leads to new species gaining niches
- Goes from pioneer species which can grow quickly through seral stages until reaching a climax community, where succession stops due to the large and complex food web being self sustaining
- Two kinds:
  - Primary – from bare rocks or sand eg after a volcanic eruption
  - Secondary – from empty soil but no species eg after a forest fire
- Humans have destroyed climax communities and prevent areas from reaching them again, through interventions necessary for agriculture – eg. Plowing, weeding, mowing, grazing animals
  - Grazing leads to a climax community of grasslands, as grazing animals such as sheep will eat the tips of shoots which kills dicotyledonous plants but not monocotyledonous plants such as grasses
Conservation
- Management to maintain biodiversity
  - This means that species diversity should be increased, and prevention of climax communities actually helps with this
  - Interventions which prevent succession, but also recognition that different areas need to be kept at different seral stages to produce maximum biodiversity
Food Chains
- Show the relationships of energy flow between organisms
- Start with a photosynthetic producer which can use energy from the sun to convert abiotic molecules to biomass
  - (Or other autotroph)
- As you go along the chain, you go up trophic levels
- Detritus, which is waste biomass from dead organisms/excretion, is used as a food source by saprobiotic organisms
- Very small amounts of energy pass from one trophic level to another, roughly 10%, the rest is all lost via respiration, undigestible biomass etc.
Nutrient cycles
- Inorganic molecules used in biological processes are known as nutrients
- Nutrients are absorbed and converted into biomass by producers, where they are passed up food chains
- Decomposers then return nutrients in biomass to the inorganic environment to be reused by producers once the organisms have died
- Carbon cycle
  - Photosynthesis is the process by which carbon is fixed from CO2 in the atmosphere to biomass
  - Respiration then returns that CO2 to the atmosphere, as the organic molecules are passed along food chains
  - When organisms die the carbon compounds in them are broken down by decomposers and returned to the atmosphere via respiration of those decomposers
  - Some carbon compounds in detritus are prevented from being broken down by decomposers due to geological processes, leading to fossil fuels
- Saprobiotic organisms secrete digestive enzymes onto their food and then absorb the soluble products
- Detritivores are small animals which feed on detritus, which start the process of breaking down detritus into inorganic molecules. They physically break down dead biomass so there is more surface area for saprobiotic organisms to feed on
- Nitrogen cycle
  - Nitrogen in the atmosphere is converted into ammonia and then ammonium ions by nitrogen fixation (by bacteria in the soil)
  - The ammonia is then converted into nitrite, and then nitrate, in a process called nitrification (again by bacteria)
  - The nitrates are absorbed by plants and used to construct proteins
  - The proteins are eaten by animals and broken down into amino acids, then used to construct new proteins
  - When organisms die, the saprobiotic organisms turn the nitrogen-containing compounds into ammonia again
  - In anaerobic conditions, bacteria convert nitrate to nitrogen, in a process called denitrification
Productivity
- Energy fixed by producers is the gross primary productivity
- Energy absorbed by consumers is the gross secondary productivity
- Net productivity = Gross – losses due to respiration, lack of digestion etc.
- Different ecosystems have different productivities, as most areas have a similar amount of solar energy on them but cannot utilise it to the same extent. Rainforests are among the most productive areas.
- Farmers want to increase the productivity as much as possible, as the greater the productivity the greater the biomass fixed into their products, which is the yield they can sell at market
  - They do this by increasing gross productivity eg. Through using fertilisers
  - They can also do it by reducing respiratory losses as seen in factory farming, where animals are restrained so they lose less energy for movement
- Fertilisers
  - Fertilisation is when nutrients are added to the soil so plants can use them to grow more efficiently as the lack of that nutrient is reduced as a limiting factor
  - Crops called legumes have mutualistic bacteria which carry out nitrogen fixation for them, by growing these crops and then ploughing them back into the soil the nitrogen fixed by the bacteria can be used to provide for future crops
  - Inorganic fertilisers produced using the Haber Process can be used to quickly and easily add Nitrate, Potassium and Phosphate ions to the soil, which are what most plants need to grow
    - This can cause problems such as eutrophication
      - This is where addition of nutrients due to human activity leads to algal blooms in ponds, which block the light of plants on the bottom and stop oxygen diffusing in to the pond, meaning that decomposers use up all of the oxygen to break down the dead plants and eventually only anaerobic organisms can survive, which produce toxic waste products
  - Organic fertilisers are basically detritus from farms which contain the nutrients needed for new plant growth stored in biological molecules, after the detritus is broken down by decomposers the plants can use the nutrients
    - It is however slower, as the decay can take a while
- Pest control
  - Chemical and biological pest control
    - Chemicals are pesticides/herbicides which directly kill pests
    - Biological pest controls are species which are predators to pests, so they are introduced to the area to kill off pest populations
  - Integrated pest management is when multiple methods are used together
  - Pest population must be reduced below the economic threshold where it does little harm
Global Warming/Climate Change
- Caused by the greenhouse effect
  - Heat reflected by certain gases called greenhouse gases
  - The concentration of these gases is increasing so the amount of heat reflected increases
- Humans have caused it
  - Burning of fossil fuels, deforestation of rainforest and heavy industry have increased CO2 concentration in the atmosphere
- Effects will be mostly negative
  - Sea level rise
  - Extinction of animal species as their climates change beyond the range they are adapted for
  - Pests will be more able to spread as climates warm to pests preferred conditions
Human Populations
- Human growth rate has increased exponentially in the past 100 years or so
- Mainly due to decreased death rate meaning people live to reproduce and have kids more often
- Democratic transition model
  - Stage 1 – High birth and high death rate – balanced
    - (Invention of better medicine)
  - Stage 2 – High birth rate and falling death rate – population growth
  - Stage 3 – Birth rate decreases, death rate remains low – slow growth
  - Stage 4 – Low birth rate, low death rate – balanced/decrease

Respiration

Glucose + Oxygen -> Carbon Dioxide + Water
The reaction is exothermic, and this energy is coupled to the synthesis of ATP from ADP and inorganic phosphate groups
ATP
- ATP is the energy carrier molecule used in biological processes
- Very soluble
- Remains inside cells
- Bond between phosphate group can be easily broken to release a useful amount of energy, returning it to ADP and Pi (inorganic phosphate)
Glycolysis
- Glucose in the cytoplasm is the starting point
- Phosphorylated using 2 ATP molecules
- Breaks down at this point into 2 separate triose phosphate molecules (TP)
- Each triose phosphate releases 2 ATP and reduces one NAD to become pyruvate
Link reaction (aerobic)
- Inside mitochondrial matrix
- Pyruvate -> Acetyl Coenzyme A (Acetyl CoA)
- Releases CO2 at this point and another NAD becomes reduced
Anaerobic respiration
- Happens after glycolysis, no link reaction
- In cytoplasm still
- In animals and bacteria
  - Pyruvate + reduced NAD -> Lactate (lactic acid) + NAD
  - Recycles reduced NAD to NAD for more glycolysis, but the lactic acid is toxic
- In plants and fungi (fermentation)
  - Pyruvate + reduced NAD -> Ethanol + CO2 + NAD
Krebs cycle (aerobic)
- Mitochondrial matrix again
- Acetyl CoA (2-carbon) combines with 4-carbon intermediate to form citrate (6-carbon molecule)
- This 6 carbon molecule breaks down to form 2 CO2 molecules, reduce one NAD and reduce one FAD, and produce one ATP from ADP
- Back to a 4 carbon molecule again so the cycle turns twice
- 2x Acetyl CoA are produced from each glucose, so it turns twice per glucose
Sum total of products at this point:
- 2x ATP from glycolysis (2 used, 2 released each TP molecule)
- 4 NAD reduced from glycolysis and link reaction
- 6NAD and 2 FAD reduced from krebs cycle
- 2 ATP from krebs cycle
- 3 CO2
Electron transport chain
- Occurs on the inner membrane of the mitochondria, on the cristae
- Reduced carrier molecules are oxidised
- This means that hydrogen atoms on the carrier molecules are stripped of their electrons and removed from the carrier
- Energy from the electrons is used to pump the H+ ions into the intermembrane space
- As the electrons pass down the chain of proteins more H+ ions are pumped into the intermembrane space
- Finally the chain ends when molecular oxygen is reduced into water, accepting H+ ions and electrons
- The H+ ions in the intermembrane space travel down a concentration gradient into the matrix of the mitochondria. This is coupled to an ATP synthesase enzyme on the end on the H+ transport protein, so the gradient of H+ ion concentration powers synthesis of ATP
Fats and glycogen can also be broken down by respiration, as well as proteins in extreme circumstances

Photosynthesis

Light dependant reactions
- Happen on thylakoid membrane in chloroplasts
- Chlorophyll pigments absorb light, exciting some of the electrons in Photosystem II to a higher energy level
- This allows water to be broken down by photolysis to oxygen, H+ and electrons inside the lumen of the thylakoid
- H+ ions build up causing a concentration gradient
- Electrons replace lost electrons from the photosystem
- High energy electrons are passed down a chain of proteins, pumping protons from the stroma into the lumen of the thylakoid
- In Photosystem I, more light energy is absorbed and the electron is increased to a higher energy level again
- This high energy electron is used to reduced NADP to NADPH by combining it with a H+ ion
- The concentration gradient of H+ ions is again used to power the formation of ATP from ADP using an ATP synthesase enzyme
Light independant reactions
- Called the Calvin cycle
- RuBP (5 carbon) + CO2 -> 2x GP (3 carbon)
- Relies on ATP and NADPH from the light dependant stage
- 2x ATP + 2x NADPH + 2x GP -> 2x TP
- Only one carbon from both of the two TP molecules combined is then removed from the cycle, to return to the original 5-carbon RuBP
- The carbon removed is then used to create glucose, which is a 6 carbon molecule
- 6 turns of the calvin cycle are needed for one glucose
Factors affecting photosynthesis
- Temperature
  - Higher temperature = higher rate
  - Until you reach the point where the enzymes denature
- Carbon dioxide concentration
  - Higher concentration = higher rate
  - Until something else becomes limiting
- Light intensity
  - Higher light intensity = higher rate
  - Until something else becomes limiting
  - Until light intensity increases the temperature so much the plant gets too hot

Genetics

Define homozygous/heterozygous
Draw punnett squares
Dominant and recessive genes
Sex determination
- This is because the egg always contains an X chromosome
- Sperm can contain either an X or a Y depending on what they picked up in meiosis
- Y chromosomes contain dominant genes for hormones which convert embryos to males
Sex linked genes
- Y chromosomes only code for sex determination
- X chromosomes contain other genes
- Therefore males only have one set of X chromosome alleles (from the mother) and whatever genotype is present will be expressed
  - Colour blindness is the usual example, which is a recessive allele and so not expressed in females, but males will always express the colourblindness gene if they inherit it
Codominance
- Not every gene has only two phenotypes, sometimes heterozygous individuals will display a third phenotype
- This is due to incomplete dominance of one allele over another, leading to both being partially expressed
  - Sickle cell anaemia is the usual example
    - This has the interesting effect that heterozygous individuals have a competitive advantage in malaria-prone areas as the malaria parasite cannot infect them as easily
Multiple alleles
- When there are more than 2 types of allele in the gene pool for a population
- Only 2 can be present in one individual, but it means there can be a variety of crosses
  - Blood typing using the ABO system is an example of this
    - A and B are also codominant, to give an AB phenotype
Population genetics
- Hardy Weinberg principle
  - Frequencies of dominant and recessive alleles will remain constant as long as:
    - There is no mutation
    - There is no migration
    - There is no selection of different alleles over each other
    - Random mating is observed
    - There is a large population
  - If these are true there is genetic equilibrium
- P + q = 1
- P^2 + pq + q^2 = 1
Natural selection
- Based on 4 observations
  - There is variation within a species
  - Characteristics are inherited
  - Most organisms die before they can reproduce
  - Populations remain constant in size
- Over time, individuals who are better adapted to the conditions they live in will be able to survive for longer and so have more offspring
- This means that the genes which created that better adaptation make up a larger proportion of the gene pool
- Eventually the entire population changes as a result of the changed gene pool
- Types
  - Directional – when there is a change in environment favouring one extreme of phenotype
  - Stabilising – when the environment is stable and the average is well adapted
  - Disruptive – when there is a sudden change in environment and opposite extremes are favoured
- Speciation
  - Formation of new species by isolation of groups of current species
  - Isolated groups will adapt to their new environments
  - When the isolated groups then meet again, the adaptations mean they are no longer able to breed
  - Therefore different species

Edexcel AS Chemistry–Unit 2

noreply@blogger.com (Alex) — Tue, 22 May 2012 19:19:00 +0000

Bonding and intermolecular forces

Electron pair repulsion theory

Bond angles

Linear 180°
Triganol Planar 120°
Tetrahedral 109.5°
Triganol Bipyramidal 90° and 120°
Octahedral 90°
Lone pairs of electrons count toward an area of electron density but as they repel to a much greater extent they reduce the bond angle by 2.5°

Bond length – the stronger the bond the shorter the length

Electronegativity

The ability to attract the electrons in a covalent bond

Ionic property of covalent bonds

Same applies the other way around

Differences in electronegativity cause permanent dipoles

Polar substances dissolve in water as they disrupt hydrogen bonding lattice

Non-polar substances will not dissolve in water

This is because there is not enough energy to make the non-polar substances break the bonds within the polar water molecules

Polar bonds break first in organic chemistry

Polar bonds are always heterolytic fission

Produces one electrophile and one nucleophile

London forces

Exist between all atoms
Weak force relative to size of electron cloud
Random fluctuation will induce instantaneous dipoles

Hydrogen bonding

Formed when hydrogen bonds to a highly electronegative atom with an unpaired electron
Formed at 180°
Strongest intermolecular bonds

Physical properties from bonding

Allotropes of carbon

Diamond – 4 bonds, giant covalent structure, requires high energy to break as there are numerous strong bonds. No conduction of electricity
Graphite – 3 bonds in flat sheets, makes it very slippery and useful as a lubricant. Weak bonds between flat layers are london forces. Delocalised electron so conducts electricity
Fullerenes – Ball shaped (Bucky ball) so strong due to distribution of bonds, conducts also
Nanotubes – Hollow tubes of carbon atoms, very strong due to rigid shape and conducts electricity

Organic chemistry

Longer chains have more electrons so greater london forces
More branching reduces boiling points as chains can’t get as close to each other so london forces are weaker

Inorganic Chemistry

Ionisation energies decrease down group 2

This is because the atomic radii increase and the shielding stays the same so the effective nuclear charge is the same but further away

Group 2 reactions:

Group 2 + Oxygen –> Metal Oxide (solid)
Group 2 + Water –> Hydroxide + Hydrogen gas
Group 2 + Chlorine –> Metal Chloride (solid)

Group 2 Oxide reactions

Oxide + Water –> Hydroxide
Oxide + Acid –> Chloride/Nitrate + H2O

Group 2 Hydroxides will also do this, 2H2O results

Group 2 sulphates

Solubility decreases down group
Test for sulphates: add to Barium Chloride, will give white precipitate

Group 2 hydroxides become less soluble down the group
Thermal stability of group 1 and 2 carbonates

Group 1 – stable, they don’t decompose from heating
Group 2 carbonates + heat –> Group 2 oxide + CO2

Stability of nitrates and carbonates increase down the group

This is because oxides are more stable, and the first elements are more polarising so they attract the oxygen away from the carbonate

Group 1 and 2 nitrates:

Group 1 decompose to nitrite and oxygen
Group 2 decompose to oxygen, nitrogen and oxide

Flame tests

Caused by electron being excited to a higher energy level, when it decreases energy level the extra energy is released as a photon

(Physics!)

Halogens are oxidising agents; their strength decreases down the group

Fluorine is the strongest oxidising agent as it has the strongest attraction from the nuclear charge where it is so small

Disproportionation with alkalis

Cold will lead to something like 2NaOH + Cl2 –> NaCl + NaClO + H2O
Hot forms the halate: 2NaOH + Cl2 –> NaCl + NaClO3 + H2O

So for bromine: cold leads to bromide, but if it’s hot you get a bromate

Iodine thiosulphate titrations

An oxidising agent will react with iodine ions
These iodine ions will then react with thiosulphate
Colour goes from yellow to colourless with just thiosulphate

Adding starch makes it go black as there are still iodine ions, as they react with thiosulphate it goes colourless

Test for halides

Add silver nitrate and colour of precipitate

White = Cl
Cream = Br
Yellow = I

Confirmation test using ammonia

Cl will dissolve with dilute ammonia
Br will dissolve with concentrated ammonia
I will not dissolve

Reaction rates

Increased by increasing:

Concentration
Pressure
Surface Area
Temperature
Alternative reaction routes – catalyst

All based on collision theory
Maxwell-boltzmann distribution curves

Total area under the graph must remain constant
Increasing rate of reaction means that more particles will be past eA on the energy scale

Equilibria

Dynamic state in a closed system due to reversible reactions
Le Chatellier’s principle says that if you change the environment, the position of equilibria will change to compensate for the environment

So increasing the pressure moves towards the less dense side etc etc.

Reactions of Alcohols

The more methyl groups the C in R-C-OH is bonded to, the more stable the molecule is
Combustion
Alcohols and sodium –> H2 and white precipitate (sodium propanoxide)
Substitution with a halogen produces halogenoalkanes

This is electrophilic substitution
Iodo/bromoalkanes need acid catalyst

Oxidisation – goes from orange to green

Only primary and secondary
Primary – aldehyde and then carboxylic acid

Aldehyde + Benedict’s –> Red precipitate

Secondary – ketone

Ketone + Brady’s reagent –> Yellow/orange precipitate

Halogenoalkanes

The more reactive the halogen, the less reactive the halogenoalkane
More methyl groups attached to the C in R-C-X make it more reactive

Electron density pulled away from the halogen

Strength of bond can be determined using aqueous silver nitrate solution (hot)

Faster precipitate = weaker bond

Free radical substitution

Green chemistry bit, with UV light

Reactions summarised:

+ Hot aqueous alkali –> Alcohol (Nucleophilic substitution)
+ Concentrated alcoholic alkali (reflux and heat) –> Alkene (Elimination)
+ Alcoholic ammonia (heat under pressure) –> Amine

AQA AS Biology Unit 2

noreply@blogger.com (Alex) — Sat, 19 May 2012 10:43:00 +0000

This unit doesn’t have the same structure as unit 1, there are loose categories based on the notes I’m using to write this… but mostly each topic is on it’s own. The key idea overall is adaptation and diversity – this is the more ecology and genetics (and adaptations therein) based part.

Polysaccharides

Starch

Plant storage polysaccharide
Forms insoluble granules inside cells

Does not change water potential

(We’ve already been tested on this in the unit 1 exam I wouldn’t worry about explaining it)

Mixture of amylose and amylopectin

(Explains the name Amylase for the enzyme!)

Forms a helix shape held together by hydrogen bonds
Broken down into maltose

Glycogen

“Animal starch”
Found in muscle and liver cells
Highly branched

Lots of ends for enzymes to work on
Therefore converted to energy easily and quickly

Enzyme called Glycogen phosphorylase

Cellulose

Main component of cell walls
Only in plants
b-glucose instead of a-glucose

Alternate molecules are inverted
Straight chains!
Hydrogen bonds link chains

Strong cell walls!
These linked chains are called microfibrils

(Bit brief again because I already did this)

Cellulase enzyme

Only produced by bacteria
Humans don’t carry this bacteria but ruminants do

So it’s called “fibre”

Diffusion and the Problem of Size

The larger an organism, the smaller its surface area to volume ratio

Therefore diffusion is slower into it

Above a certain size, diffusion is too slow to support life

Maximum size of a normal cell: 100um
Heat exchange the same way so larger animals are better adapted for cold environments

Gas Exchange

Small organisms

Large SA:V ratio, therefore simple diffusion
Low metabolic rates

Insects

Waterproof exoskeleton

Prevents drying out and supports organs

Spiracles, pores in the exoskeleton, allow air in and out

These pores lead to tracheae and tracheoles strengthened by chitin
Air pores go directly to the cellular level

Actively respiring cells produce lactic acid, lowering the water potential and so causing water to go into the cells

This then means the air can reach closer to the cell as the water layer around it is thinner

Therefore, rate of diffusion is faster

Fish

Concentration of oxygen in water is low
Gills are exchange organs

Composed of filaments with lamellae on

Lamellae only a few cells thick with capillaries inside

Large surface area and small thickness

High rate of diffusion

If a fish is taken out of water the gills collapse and water is needed to cushion each individual lamellae

Ventilation

One way ventilation

In through the mouth, out through the fin valves

The water flows in the opposite direction to the blood in the gills so a constant concentration gradient remains
80% of oxygen is extracted

Plants

Gases enter the leaf through the stomata
The spongy mesophyll cells then transport gas in and out of the plant
Water loss is the main problem by transpiration as the mesophyll cells must be damp to dissolve O2

This is reduced as there is a waterproof cuticle on the upper cuticle
Pitted stomata trap a space of moist air, reducing the concentration gradient
Guard cells can close stopping water loss and gas exchange

No ventilation as leaves are highly exposed

Human Circulatory System

Humans have a double circulatory system

This means we have two sides to our heart which pump blood to different places

The sequence of blood vessels is as follows:

Heart > Aorta > Arteries > Arterioles > Capillaries (outward journey)
Capillaries > Venules > Veins > Vena Cava > Heart (return journey)

The purpose of the blood vessels is to deliver blood to capillaries, which are spaced every 100um in the body at least

There is not enough blood to supply every capillary, so 20% of capillaries are closed off at any time

This is obvious when you consider your skin going red/pink when you exercise – heat exchange has become a priority so capillaries that were closed off mostly open up and others (in the gut) close down

Structures of blood vessels

Arteries

Thick walls of elastic tissue and muscle fibres

Allows artery to expand without bursting and resist high pressures
Expansion and contractions even out pressures in the blood flow

Capillaries

Very narrow
Walls are single endothelial cells
Gaps in wall allowing substances to dissolve out freely
Huge surface area in total

Veins

Thin inelastic walls
Thicker lumen
Valves

These prevent blood flowing backwards as blood in the veins is at low pressures

Contractions of nearby muscles help push blood up from legs etc.

Hence not moving your legs can cause DVT as there are no contractions to pump blood

Tissue fluid

Bathes all cells
Final site of transport
Formed from blood plasma

High pressure in arterial end of capillary forces blood plasma out into tissue fluid
Materials transfer between tissue fluid and cells by all 4 methods of transport
At venous end of capillary there is low pressure so blood plasma is reabsorbed
Some plasma is not reabsorbed, this drains into the lymph system

The lymphatic system

A secondary system for exchange and transport in the body
It reabsorbs into the blood near the vena cava
Has three main roles:

Drains excess tissue fluid
Absorbs fats from the small intestine
Forms part of the immune system, allowing white blood cells to develop in lymph nodes

Transport of Oxygen

Haemoglobin

Protein molecule that allows red blood cells to carry oxygen more efficiently

20% concentration rather than 1%

One haemoglobin can carry up to 4 oxygen molecules
Picks up and releases oxygen according to the oxygen dissociation curve

This is a graph showing the percentage saturation of oxygen in haemoglobin depending on the partial pressure of O2 in the environment
This explains why the haemoglobin becomes saturated in the lungs, as there is a high pressure of oxygen
In respiring tissues there is less oxygen so it unloads from the haemoglobin
Respiring tissues also form CO2, which then dissolves to form carbonic acid, moving the curve to the right and so meaning more O2 unloads

Water transport in plants

Water is transported by xylem vessels

Xylem vessels are dead cells that merge together to form long hollow tubes
Rings of lignin form in the walls to allow the xylem to withstand pressure

Transport in the roots

There are two pathways for water to travel through the roots

The symplast pathway – through the cytoplasm
The apoplast pathway – through the cell walls

This stops at the casparian strip, forcing all water into the cytoplasm inside the endodermis

This active absorption of water means that a pressure is produced in the xylem – root pressure

This is quite weak however

Mass flow in the stem

As water leaves the leaves there is a tension to pull more water up to replace it
The thin tubes of the xylem mean that capillary action pulls the water up as it is stretched
Strong walls is needed to stop the xylem collapsing under the pressure

Diffusion through the leaves

There is a water potential gradient in the leaves because of transpiration so water leaves the xylem into the cells

Factors affecting transpiration

Light – makes the stomata open so gas exchange is needed and transpiration must occur
Temperature – water will have more kinetic energy so it’s more likely to evaporate
Humidity – high humidity means there is less of a concentration gradient so water leaves less quickly
Air movement – wind will blow saturated air so the concentration gradient remains constant

Examples of adaptations

Thick cuticle – prevents evaporation through top of leaf
Small leaf surface area – cactuses and conifer needles
Sunken stomata/hairy stomata – trap pocket of saturated air
Succulent leaves and stem – water storage
Extensive roots – collects more water

DNA

Nucleotides

Contain elements CHONP
Three part structure

Phosphate connected to a pentose sugar, connected to an organic base

5 different bases, Adenine, Cytosine, Guanine, Thymine and Uracil

Thymine in DNA = Uracil in RNA

Each base joins to one other base to form a base pair

Guanine and Cytosine (3 hydrogen bonds)
Adenine and Thymine (2 hydrogen bonds)

Join together to form polynucleotides by condensation reactions

DNA structure

Double stranded
Antiparallel strands
Double helix structure
Hydrogen bonds hold strands together
Benefits of structure:

Makes it strong so it can’t be damaged easily
Bases can be used to encode information
DNA can be very long so lots of information stored
Complementary strands means there are two copies of information

Errors can be spotted easily

Replication

Used to produce two copies of DNA for cell division
One strand conserved in each replication, one new strand assembled

Remember the experiment with heavy nitrogen

(I’m not writing about it because it’s boring and I know it)

Process:

DNA Helicase unwinds and separates two strands of DNA
Free nucleotides attach to exposed bases (following base pairing rule)
DNA Polymerase joins the nucleotides together
Another enzyme winds the new strands into helixes

DNA replication speed is the limiting factor of cell division

Function

DNA determines the sequence of amino acids in a polypeptide

This in turn determines the shape of the protein

This in turn determines the functionality of the protein

This in turn determines how cells work

A gene is the DNA sequence for one polypeptide

The triplet code

Every three combinations of base pairs codes for one amino acid
64 possible combinations, most amino acids have more than one code

Control genes

Some genes do not code for proteins but instead determine what other genes activate at particular times

This is important because all body cells have the full genetic code, control genes determine what parts of the genetic code are expressed

Mutations

These are small errors in replication of DNA
Most of the time they either have no effect or stop a gene from functioning
Occasionally they will have a positive effect and this is what causes evolution

Chromosomes

Chromosomes are formed of two sets of the same chromatid (a section of the total DNA)
They are joined at the centromere
They form because there is temporarily twice the usual amount of DNA in the cell before replication, so it must be wound up tighter than usual to fit within the nucleus – this makes complexes big enough to see
Humans have 46 chromosomes in 23 pairs

(and don’t forget each chromosome is double the usual amount of DNA needed)

Chromosome pairs are not identical, but they do contain the same type of genes

One of each pair comes from each parent, and so can contain different alleles of each gene

Mitosis and the Cell Cycle

Mitosis is needed to produce new body cells – either to grow, replace or repair
It is also used to produce new organisms for asexual reproduction
The cell cycle:

Interphase

90% of cell cycle
Spent performing usual cell functions
Includes 3 phases:

G1 – Cell regrowing and recovering organelles after mitosis
S – DNA replicated
G2 – Spindle proteins replicated

Mitosis

Prophase

Chromosomes condensed and visible
Centrioles form at opposite poles
Nucleolus vanishes

Metaphase

Nuclear envelope vanishes
Chromosomes align along centre of cell
Spindle fibres form between centrioles and chromosomes

Anaphase

Centromeres split
Chromosomes start to diverge
Centromeres travel along spindle fibres to opposite sides of cell

Telophase

Spindle fibres disperse
Nuclear envelope reappears around new sets of chromosomes
Chromatids uncoil

Cytokinesis

The cytoplasm splits and the cells become seperate

Usually there is control over how often cells can divide

If these controls stop working, this is cancer

Meiosis and Sexual Reproduction

Meiosis differs from mitosis because it results in 4 cells rather than 2, each with half the usual number of chromosomes
This is because the sex cells combine with another sex cell, so the zygote will have the normal number once they have joined together
Chromosomes are re-arranged to form new combinations of genes in order to create genetic variation in the zygote

This is achieved in three ways:

Independent assortment – The homologous chromosomes pair up independently of each other, so the final meiosis cells can have any combination of maternal and paternal chromatids
Crossing over – When the two homologous chromosomes pair up, they become tangled together and then cut of when separated with part of the paired chromosome on one chromatid each swapped between the two, so the final meiosis cells will have combination maternal-paternal alleles on each chromatid
Random fertilisation – The sperm that reaches the egg could contain any combination of alleles, it is more or less random what sperm and what egg will fuse together

Antibiotic resistance

Antibiotics kill bacteria, often by weakening their cell walls so they burst under pressure

70S ribosomes are also a common target of antibiotics

Mutations in bacteria can make them resistant to antibiotics

When the antibiotics are then used, the bacteria which are resistant will survive and pass on this mutation to their offspring

This is because they have a selective advantage – the environment contains antibiotics so being resistant to them gives them the change to survive

Mutations can also be passed on through genetic conjugation, where one bacteria donates a gene to another

Classification

Defining a species:

Organisms that are similar in appearance, biochemistry and fulfil the same ecological niche
Organisms that can breed to produce fertile offspring
Organisms that share a common ancestor

Species are formed when two isolated populations of the same species diverge from each other in terms of evolution

Eventually they will become too genetically different to breed

Species are the bottom rung of taxonomic hierarchy:

Kingdom
Phylum
Class
Order
Family
Genus
Species

The further down the hierarchy the more closely related two organisms are
Names of species are binomial, with the genus and species given to identify positively one species within the entire tree of species
Phylogenetic trees are also used to classify species, this is according to evolutionary relationships rather than groupings

The earlier a path splits on a phylogenetic tree, the more distantly related the groups are, as the point of splitting shows the last common ancestor

DNA Classification

This is where you create a hybrid DNA molecule from one strand each of two species DNA
The closer the species are related, the more of the bases will match up
Therefore, closer species will form more hydrogen bonds and require higher temperatures to break apart

Protein immunology classification

This is where you inject an animal (eg a rabbit) with protein from a species
The rabbit will produce antibodies against that protein
Collect these antibodies, then react them with proteins from different species
The closer related a species is, the more antibodies will react with it and so the greater the volume of sediment produced

Courtship behaviours

Contrary to human belief, courtship behaviours are intrinsic

This means they are genetically coded into species and aren’t a matter of choice

The purpose of courtship behaviours is to ensure that individuals only attempt to mate with compatible mates

This means they’re of the same species, sexually mature and fertile

Genetic Diversity

Genetic diversity is important as it means species are more likely to have the tools needed to survive a change in the environment
Genetic diversity is however lowered in three main ways:

Genetic Bottlenecks – When some event occurs that wipes out a large number of a species, therefore meaning the remaining individuals will have a reduced range of alleles
The Founder Effect – When only a small number of settlers become isolated from the main population, the effect of every allele carried by these settlers is increased, as there are few settlers and so few alleles

Not just geographically isolated either: Amish people only get married to other Amish people as a rule and nobody joins the community, so there are only a few alleles in circulation

Selective Breeding – When people choose to control the individuals allowed to breed in a species based on desirable characteristics, individuals with other characteristics die out as they are not able to pass these on

Measuring species diversity

Some maths or something we didn’t do so I don’t think we need

It’s called the Simpson Diversity Index, look it up if you care

Edexcel AS Chemistry–Unit 1

noreply@blogger.com (Alex) — Mon, 14 May 2012 15:20:00 +0000

Chemical quantities and formulae

Definitions:

Elements are substances which cannot be broken down by chemical means into other substances
Atoms are the smallest part of any elements that can take part in chemical reactions
Ions are formed when an atom gains or loses electrons, in other words a charged atom
Compounds are formed when two or more elements bond together
A molecule is a covalent compound
Empirical formulae are the simplest ratios of atoms possible for a given compound
- Three steps to working these out:
  - Divide the mass (or percentage, assume it’s 100 total mass) by the molar mass of the element
  - Divide the results of the first step by the smallest result of the first step
  - This is the ratio of elements (to the nearest whole number)
Molecular formulae are the formulas as found in reality ie. multiplied to fit the actual mass value recorded

Ionic equations:

Include something if it changes state
Make sure both sides balance charges and all other ions
- Change in charge and no balanced change in charge? Add an electron to balance!
  - (This is more for half equations)
- The quick way to do half equations when you’re including acidic/alkaline conditions as well is to balance the H+ or OH- from the amount of water produced and then balance the charge with electrons

Concentrations and calculations:

Concentration = moles/amount of solute
- (Alternatively can be done with grams)
Three steps to working out the numbers in a chemistry paper:
- Get a balanced reaction written down
- Figure out the mole ratio of what you’re calculating
- Times the number of moles by the mole ratio
Avogadro’s constant
- It’s written on the sheet or so I’m told, but what it tells you is the value of a mole
  - That rhymes kill me now
    - There' is a number, oh haven’t you heard? It’s six point oh-two to the twenty third
  - Avogadro’s constant = the amount of a substance particles required to form one mole of a substance
    - 6.02 x 10²³
Gas volumes
- In standard conditions: 1 mol of a gas fills 24dm³of space
  - Use this value instead of the mass in grams to work out the number of moles in a gas
Percentage yield
- Get the theoretical yield (from a standard calculation)
  - The actual yield by the theoretical yield and times it by 100
    - If you get more than 100%, you screwed up!
    - If you get 100% and there’s more than one product? You screwed up!
Atom economy
- All theoretical
- It works out how effective your reaction is in terms of atoms in to useful atoms out
- RFM of product/RFM of reactants x 100

Enthalpy changes and kinetics

Enthalpy level diagrams:

X axis = reaction stage (roughly time)
Y axis = energy level
- Exothermic reactions have energy exit the system, so the energy level decreases
- Endothermic reactions have energy enter the system, so the energy level increases

Definitions:

Standard conditions – 298K and 100kPa pressure (or 1Atm pressure)
- Remember all standard enthalpy changes will be based on reactants in the states they are at in these conditions
Standard enthalpy change of reaction – The standard enthalpy change of a reaction is the enthalpy change which occurs when equation quantities of materials react under standard conditions, and with everything in its standard state
Enthalpy change of formation – The standard enthalpy change of formation of a compound is the enthalpy change which occurs when one mole of the compound is formed from its elements under standard conditions, and with everything in its standard state.
- Formed from elements! So 1/2 O2 not 1 O
- 1 mole of the product formed
Enthalpy change of combustion - The standard enthalpy change of combustion of a compound is the enthalpy change which occurs when one mole of the compound is burned completely in oxygen under standard conditions, and with everything in its standard state.
Bond enthalpy – Energy required on average to break 1 mole of a type of bond
Relative atomic mass – Mass of a particle relative to 1/12 of C12
- Also the average mass of an element’s isotopes worked out by the ratios of their relative abundance

Calorimeter experiments:

Assumptions:
- All energy is transferred into water (no loss into environment)
- Calorimeter does not absorb any heat
- Fuel has undergone complete combustion
Calculation to be done:
- Mass x specific heat capacity x change in temp = change in energy
  - Then work this out per mole: energy produced/moles of fuel
Always negative enthalpy

Hess’s Law:

The total enthalpy change of a reaction is the same no matter what route you take
- Therefore, using data values you can work out the enthalpy change of a reaction by going an alternate route
Draw the arrows on the hess’s law diagram according to the route they reaction would take – eg if you’re given combustion data then the lines are from the reactants and products to the combustion products below

Mass spectrometry:

Works by ionising the molecule to be tested through bombardment of electrons
Ions accelerated with an electric field and deflected with magnets
These ions then hit the detectors at different points as different masses will be moved more/less by the same magnetic field
The greatest mass is always the molecular ion – RFM of the original molecule
Other peaks are caused by fragmentation – splitting of molecule into two ionised chunks

Ionisation energy and atomic structure

Definition:

Ionisation energy – the energy required to remove 1 mole of electrons from 1 mole of gaseous atoms

Evidence for electron shells:

Ionisation energy has steep jumps in it at point where shells change
- These jumps mean that there must be a large difference in energy level
  - Energy level = shell
Subshells can be explained in a similar way
- s orbitals – 1 pair (2 electrons)
  - Li and Be fill this, so B has a lower energy as it has started the p ortbital
- p orbitals – 3 pairs (6 electrons)
  - N has a slightly higher ionisation energy than O, as it has got one electron in each of the 3 orbitals, and O has a second in one orbital which feels repulsion
- d orbitals – 5 pairs (10 electrons)
  - Don’t worry about this

Melting and boiling points:

Giant molecular structures
- C and Si
- High melting points as there are lots of strong bonds so a high lattice energy
Metals
- Li, Mg, Na, etc.
- Sea of delocalised electrons create lots of bonds so high melting point
Simple covalent bonds
- Small enough to melt unless held together by intermolecular forces
  - eg. London forces and hydrogen bonding
- Intermolecular forces are weak so low melting point

Ionic bonding:

Evidence for ions:
- Electrolysis allows splitting of particles by charge
- Conduct charge in solution/when molten only
- Electron density maps with 0 density in between
Ions will attempt to gain noble gas configuration
- Anions are negatively charged - they gain electrons
- Cations are positively charged – they lose electrons
Ionic lattices are formed when oppositely charged ions mix, so they each try and get as far away from similarly charged particles as possible while also being attracted to oppositely charged ions
Trends in ionic radii:
- Increase down groups (more electron shells)
- Cations are smaller than anions
- Isoelectronic ions depend on the number of electrons gained or lost:
  - N^3-> O^2- > F^-> Ne > Na⁺ > Mg²⁺ > Al³⁺
  - The stronger the nuclear charge, the smaller the ionic radius
Born-Haber cycles are complicated Hess’s law cycles used to determine the reaction energy from formation of a lattice
- Latice energy is always exothermic
  - That means it’s a negative number
Ions may be polarised
- This is where their electron cloud is distorted from spherical due to additional charges acting on the ion

Covalent bonding:

Involves sharing a pair of electrons between two atoms
Dative bonds are when both electrons come from one atom
Can form double/triple bonds with multiple shared pairs
Lone pairs can also affect the shape of covalently bonded molecules as they contribute areas of electron density

Metallic bonding:

The attraction between metal ions and a sea of delocalised electrons
Electrical and thermal conductivity because of movement of electrons throughout the sea
Strong attraction due to the amount of electrons
Malleable as atoms can slide along and remain surrounded by electrons

Organic Chemistry

Alkanes

Saturated hydrocarbons
C_nH_2n+2
Fuels separated out by fractional distillation

Cracking and reforming used to change lengths of alkanes

Cracking results in a smaller chain and an alkene

Carried out by heating over a catalyst of porous pot

Reforming is also breakdown but increases the proportion of aromatic compounds

Reaction mechanism: Free radical substitution

Initiation step: Cl₂ -> 2 Cl∙
Propagation step:

CH₄ + Cl∙ → ∙CH₃ + HCl
∙CH₃ + Cl₂ → CH₃Cl + Cl∙
Must maintain one free radical on either side at all times

Termination: Two free radicals combine

Alkenes

Unsaturated hydrocarbons
Contain a double bond

One sigma bond
One pi bond

Pi bonds are non-rotational so you get stereoisomerism

If you have matching functional groups on the top, it’s a cis-whatever-ene, else it’s trans
If you have no matching functional groups, the largest molecular mass is used to decide if something is z-whatever-ene or e-whatever ene

Z = zimmilar (how I remember it) – both sides big

Reactions:

Hydrogenation – forms an alkane
Halogenation – di-substituted halogenoalkane

(Yeah what?)

Addition of hydrogen halide (ie HCl, HBr) – Halogenoalkane

Gotta know the mechanism of this
Oxidation with acidified KMnO₄ - Diol

Polymerisation

AQA AS Biology Unit 1

noreply@blogger.com (Alex) — Sun, 13 May 2012 12:12:00 +0000

This unit contains three main areas:

Biological Molecules
Cells
Physiology and Disease

(According to the revision notes I'm summing up in this post - we learnt it differently in class)

Biological Molecules

Carbohydrates

Contain Carbon, Hydrogen, Oxygen
Polymer name: polysaccharides; Monomer name: monosaccharides
Includes Glucose and its isomers:

a-glucose - you must know the simplified structure of this (in the textbook)
b-glucose - a-glucose but with the right hand OH and H groups swapped
Galactose
Fructose

Disaccharides are combinations of two monomers linked by a glycosidic bond

The OH groups of two monomers join together, releasing water and leaving behind one O which is where the bond is formed
You have to know three disaccharides composition as far as I know, if there's more I don't know of then good for you

Maltose = a-glucose + a-glucose
Sucrose = a-glucose + fructose

Bit of GCSE here: this stuff is really sweet, so an enzyme called Isomerase is used in industry to convert glucose to fructose which then makes sucrose rather than maltose. Use the sucrose in foods, and you'll need less sugar for the same taste, which is good for diet foods

Lactose = a-glucose + galactose

Polysaccharides include starch and cellulose:

Starch is a helix formed of lots of a-glucose
Cellulose is straight sheets of b-glucose

Lipids

Contain Carbon, Hydrogen, Oxygen, Phosphorus (for Phospholipids)
Don't follow the monomer/polymer way of looking at them:

They are made up of fatty acids + glycerol

Glycerol is Propan-1,2,3-triol to put it a chemistry way, or a 3-carbon long molecule with an OH group on each carbon
The bond is called an ester bond but it's functionally the same as a glycosidic bond - an OH from glycerol joins up to the OH from the fatty acid

(Fatty acids are carboxylic acids, chemists, if that helps you understand)

Three fatty acids and a glycerol makes a triglyceride (see where the name comes from)

Knowing the difference between saturated and unsaturated is important when dealing with these:

Saturated molecules have no C=C double bonds
Monounsaturated molecules have one C=C double bond
Polyunsaturated molecules have multiple C=C double bonds

The more unsaturated you get, the lower the melting point of the oil/fat
Also saturated fats are bad for you in terms of heart disease, as they can solidify in blood vessels (higher melting point) and so cause blockages

They are insoluble in water, and form fats and oils, so they can't be transported around the body too quickly
Useful for energy storage, as they release a large amount of energy for their mass when broken down
They also insulate and protect major organs
Phospholipids are like triglycerides but with a phosphate group instead of one fatty acid

This means that the molecule becomes polar
The phosphate group "head" is attracted to water but the two fatty acid "tails" are insoluble and repelled by water

(Chemists again will get why this is: the phosphate head can disrupt the hydrogen bonding between water molecules)

These are core components of cell-surface membranes

The phospholipids form a bilayer - a bubble of water surrounded by two sets of phospholipids facing opposite directions so no tails are exposed to water and neither are any heads facing away from it

Proteins

Proteins make up 50% of dry cellular mass, as well as structural components of the body eg. collagen
They also provide roles in transport and digestion: as enzymes or transport molecules (eg haemoglobin or cell surface transporters)
Also: antibodies are proteins, which we'll go into in the immunology section
Contain Carbon, Hydrogen, Oxygen, Nitrogen, Sulphur
Polymer name: Polypeptides; Monomer name: Amino acids

Amino acids are made up of an amino group (NH₂), a carboxyl acid group, a R group (the functional part) and a hydrogen atom all around a central carbon

The important part is the R group, which varies from one amino acid to another

There are 20 different types, and so 20 different amino acids found in the body
Each different R group gives the amino acid different properties when it comes to bonding, which changes the structure of the protein overall

The bonding in proteins is called peptide bonds but it's, again, the same stuff as in carbohydrates and even more similar to fatty acids: the OH from the carboxyl group joins to a H from the amino group to give off water
Protein structure is developed into 4 stages:

Primary structure - the sequence of amino acids bonded together in the polypeptide

This sequence is determined based on the DNA in the cell

Secondary structure - folding based on hydrogen bonds between amino groups and carboxyl groups, usually found in 2 forms:

a-helix - The polypeptide chain winds up to form a helix where the hydrogen bonds are parallel to the length of the helix. Lots of bonds in this, so it's a strong, stable structure
b-sheet - The polypeptide chain goes in flat segments and then folds over itself so hydrogen bonds from between each flat layer

Tertiary structure - The 3D shape resulting from folding up of the entire polypeptide chain, based on additional bonds being formed due to the R groups interacting with each other
Quaternary structure - The combination of multiple polypeptide chains into one final protein, including any prosthetic groups (components that aren't polypeptides such as the iron in haemoglobin)

The final shape is either globular or fibrous: roughly spherical or long and straight, depending on the role of the protein in the body

Protein denaturing - as hydrogen bonds are relatively weak, if you change the temperature or pH of the environment a protein is in, its secondary and tertiary structures will start to break down, stopping the protein from working

Biochemical tests

Starch: Add iodine, it'll go black if there is starch present
Reducing sugars: Benedict's test - add benedict's reagent then heat the sample in a water bath, more brown/red colour means there is reducing sugar present
Non-reducing sugars: Test with benedict's - if negative, then add dilute hydrochloric acid to a new sample and allow a few minutes to react before neutralising with sodium hydrogen carbonate. Test again with benedict's and if it now goes red/brown then it is a non-reducing sugar (sucrose)
Lipids: Dissolve the lipid in ethanol, then add the ethanol solution to water. If the water goes cloudy, lipids are present
Protein: The biuret test - add biuret solution and see if the solution goes purple after shaking

Enzymes

Proteins which act as biological catalysts

Like chemical catalysts they provide an alternative reaction pathway with a lower activation energy, so the reaction is more likely to happen

Each enzyme matches a particular substrate

This is due to the specific shape of the active site on the enzyme as determined by its tertiary and quaternary structure

The substrate reacts with the amino acids in the active site creating/breaking bonds - if the wrong amino acids are there or the shape isn't right, the reaction can't happen

NOT a lock and key model, instead an induced fit like a hand and glove. The enzyme's active site is complementary to the substrate and in the presence of the substrate changes shape slightly to fit around it

The movement also provides the pressure on parts of the substrate molecule needed to break it down

Enzymes include small non-protein components called "coenzymes" (often derived from vitamins) which help the reaction to take place
Factors affecting the rate of enzyme action:

Temperature - Higher temperature gives molecules more kinetic energy and so makes them more likely to hit an enzyme's active site and react. However, above a certain temperature the enzyme will be denatured as the hydrogen bonds determining its active site's shape will be broken down
pH - Changing the pH changes the availability of hydrogen ions, which can affect the hydrogen bonding. Also, some R groups become charged in different pH ranges which changes the bonding characteristics of the active site
Enzyme concentration - The greater the enzyme concentration, the more enzymes there are available to catalyse the reaction so the rate will increase. However after a certain concentration another factor will become rate limiting
Substrate concentration - Similar to enzyme concentration, but it is much more likely that the substrate concentration will become rate limiting
Presence of inhibitors - Increasing the amount of inhibitor will reduce the amount of enzymes free to catalyse reactions so the rate will decrease

Competitive inhibitors - Molecules with similar structures to the substrate which can bind with the enzyme but will not react, therefore blocking the enzyme so the substrate can't bind there
Non-competitive inhibitors - Molecules that aren't similar to the substrate and don't bind at the active site, but join to another part of the enzyme and change its shape so the active site no longer works

Cells

Prokaryote

Without a nucleus
Bacteria
Always unicellular organisms
Smaller ribosomes
No cytoskeleton
Circular DNA without proteins

Eucaryote

With a nucleus
Everything but bacteria
Either unicellular or multicellular
Larger ribosomes
Has a cytoskeleton
DNA linear and joined to proteins to form chromatin

Organelles:

Cytoplasm

Solution within the cell membrane containing all the organelles and the molecules needed for the cell to function

Nucleus

Largest organelle
Surrounded by nuclear envelope which controls the exit of RNA and ribosomes
Contains nucleoplasm which holds chromatin (DNA)
Nucleolus is a darker region which makes ribosomes

Mitochondria

Site of respiration
Double membrane with folded cristae on the inside

Gives a large surface area

Inside of membranes is matrix which is site of ATP production

Chloroplast

Bigger than mitochondria
Site of photosynthesis
Inside of membrane is the stroma
Contains stacks of thylakoids called grana floating in the stroma
Thylakoids contain chlorophyll and are site of photosynthesis
Starch grains also found inside chloroplast

Ribosomes

Smallest organelles
Found free in the cell or attached to ER (forming Rough ER)
They produce proteins from their RNA template

Endoplasmic Reticulum

Made up of a series of flattened membranes
Processes proteins, lipids and carbohydrates for use in the cell or export to the surroundings

Golgi Body

Also flattened membranes
Transports proteins from RER to cell membrane for excretion
Produces lysosomes containing chemicals for transport

Vacuole

Membrane bound sacs of liquid
Most commonly plant cell vacuoles which contain the cell sap needed to retain turgidity

Lysosomes

Membrane bound vesicles produced from the ER or Golgi which contain enzymes that break down parts of cells so the materials can be recycled
Responsible for internal digestion within the cell

Cytoskeleton

Network of protein fibres that gives the cell support
Responsible for cell movements
Specific cytoskeleton fibres involved in cell division are called centrioles

Microvilli

Small extensions of the cell membrane which increase the surface area for absorption

Cell membrane

Flexible outer layer of the cell
Formed of phospholipids mainly with proteins and cholesterol to add rigidity
Controls the entrance and exit of substances through the cell by direct diffusion or use of a transport protein
Carbohydrates attached to proteins can be signals for other cells - eg antigens

Cell wall

Cellulose structure on the outside of plant cells
Provides strength and rigidity for the cell
Freely soluble
Prevents plant cells from bursting in solutions with higher water potential

Plasmid

Circular loop of DNA found in bacteria used to transport DNA between cells

Slime capsule

Thick layer of carbohydrates on the outside of the cell wall in bacteria
Sticks cells together into a biofilm
Protects the cell from chemicals and water loss as well as phagocytosis
Emergency food source

Flagellum

Tail used for cell propulsion
Driven by H+ gradient across cell membrane at protein motor area

Endosymbiosis: the idea that eukaryotic cells developed as a result of multiple prokaryotic cells engulfing one another, with the smaller cells becoming organelles

(I don't think we need to know this at all, but basically because organelles are a lot like small cells in their own right, perhaps they once were)

Cell fractionation

Done using a centrifuge
The liquid left after centrifuging is the supernatant
The solid removed after centrifuging is the pellet
Order of organelles separating out:

Low speed: Nucleus
Medium speed: Mitochondria and chloroplasts
High speed: ER, Golgi, bits of membrane
Highest speed: Ribosomes

Prepare cells for centrifuging in a cold, isotonic, buffered solution

Cold to slow down enzyme reactions
Isotonic to stop organelles from shrinking or bursting due to osmosis
Buffered to prevent pH changes damaging the cells

Microscopy

Measurements used are SI:

1m = 1m
1mm = 1x10^-3m
1um = 1x10^-6m
And so on, keep dividing it by three powers of 10

Magnification definition: the amount of times larger than life the image is - M = I/A
Resolution definition: the smallest separation at which two objects can be distinguished
Types of microscope:

Light - Cheap, widely used, and can have living or dead samples with stain added. 200nm resolution - too big to be able to see organelles
Transmission electron microscope - Much greater resolution of less than 1nm to be able to see more details, however samples must be within a vacuum and the preparation of samples can leave artefacts

Transport into and out of cells

Lipid Diffusion/Simple Diffusion

Lipid soluble or very small molecules can just push directly through the cell membrane and into the cell
Steroids are lipid soluble
Water, oxygen, carbon dioxide and the like are all small enough to push through

Osmosis

The movement of water from an area of high water potential to lower water potential through a partially permeable membrane
In other words, if something is too big to move, then the water will come to it to balance the concentrations
Water potential starts at 0 for pure water, and decreases as the amount of solute increases
Hypotonic solutions are those with higher water potential, hypertonic solutions are those with lower water potential, and isotonic solutions are those that are equal
Cells will shrivel up or burst if they are put into a medium with the wrong water potential

They will burst if put into a hypotonic solution
They will shrivel if put into a hypertonic solution

Facilitated diffusion

Transport of a molecule by a protein along its concentration gradient
Each protein fits a specific molecule (due to its structure)
Channel proteins are those with a water filled section that allows charged ions through
Carrier proteins are those which open and close on opposite sides, taking in molecules and then pushing them out on the other side of the membrane

Active transport

Requires energy and ATP
Transports molecules up their concentration gradient
Works in the same way as a carrier protein for facilitated diffusion but ATP provides the energy for a change of shape
Combining active transport and facilitated diffusion proteins can be used to make cotransporters where one molecule's concentration gradient powers the movement of a different molecule

Factors affecting diffusion

Fick's law - the rate is equal to the surface area x the concentration difference over the width of the exchange surface
Therefore increasing the surface area, the concentration gradient or decreasing the width of the exchange surface increases the rate of diffusion

Physiology and Disease

Requirements for a pathogen to cause disease (jesus this was like the first lessons we did)

The pathogen must be transmitted to the human host

eg. Water, food, breathing, animal bites or contact with infected people

The pathogen must gain entry to the body

eg. Through a wound or an exchange surface as this provides good condition for pathogens to grow

The pathogen must evade the immune defences
The pathogen must harm the host

Viruses reproduce inside host cells, using up cellular resources and then burst out damaging the cell membrane and killing the cell
Production of toxins by some pathogens will disrupt cellular functions by binding to receptors, blocking transport channels, inhibiting enzymes etc.

Lifestyle and risk factors

First off correlation does not imply causation and please remember that if they ask. Just because there is a link between two factors does not prove one of them is the cause of the other, only a direct relationship with lots of evidence proves that
This part is really wishy-washy and depends on the specific questions they ask
Basically, if you smoke, eat unhealthily etc. this can increase your risk factors and you need to be able to spot this on a graph

The digestive system

Know the path of food once eaten:

In the mouth there is mechanical digestion from the teeth and some chemical from salivary amylase
The oesophagus is the tube food goes down to the stomach, where it is pushed down by peristalsis, the contraction of muscles to push the food down
In the stomach the food is mechanically digested by the contraction of muscles and also bathed in hydrochloric acid to kill bacteria. Pepsin (protease) enzymes work here to break down proteins
In the small intestine, bile is sprayed on the food to neutralise the acid and emulsify the fats so there is a greater surface area. Then pancreatic juice is added to the food which contains enzymes to break down carbohydrates, fats and proteins
Also in the small intestine, broken down monomers are absorbed into the blood through villi in the wall of the intestine and then into capillaries. Villi have a large surface area, so the rate of diffusion is very quick
In the large intestine water is absorbed from the food, leaving the indigestible parts to form the faeces

Lactose intolerance

Some people don't produce lactase enzymes once they grow out of childhood

This is because lactose is not meant to be drunk naturally past childhood, and only in human societies do we drink milk, so the gene for lactase production is never switched off like in nature

This means that lactose will travel into the large intestine, where bacteria in the gut break it down into gases like methane and carbon dioxide as well as acids
As a result the person has a lowered water potential in the large intestine and water doesn't get absorbed, leading to diarrhoea

Cholera

Cholera is a disease caused by Vibrio cholerae, a bacteria
The symptoms include cramps, vomiting, fever and diarrhoea

This is because the bacteria produces a toxin which keeps a chloride ion channel in the cell membrane of epithelial cells open
As a result, the water potential of the lumen is lowered when chloride ions enter it
Water is therefore lost from cells causing dehydration and diarrhoea
75% of patients will die with no treatment

Treatment is by Oral Rehydration Therapy

This is where a mixture of salt and glucose is drunk, providing the necessary molecules to activate the sodium-glucose cotransport protein
Once sodium and glucose are inside the cell they lower its water potential and therefore reduce the symptoms as more water will remain inside the cell

The Gas Exchange System

The alveoli are the exchange surface of the gas exchange system

These are small air sacs only a single cell thick

This provides a large surface area and small distance to diffuse across, so quick diffusion
Also there is a large blood supply, which maintains a concentration gradient
Constant ventilation from breathing in and out maintains a concentration gradient in the air as well as the blood

The cells in the alveoli produce a surfactant to reduce the surface tension of the water on the cells and prevent the alveoli collapsing
Some cells also secrete mucus to trap bacteria and stop them infecting the body

Ventilation (AKA breathing)

The lungs aren't muscular so they can't move themselves
Instead, the thorax (the ribcage and chest) moves, compressing the lungs so there is a greater pressure in them, and leading to air being forced out

When inhaling, the internal intercostal muscles relax, and the external intercostal muscles contract, the diaphragm contracts and flattens downwards
This increases the volume of the thorax, and the volume of the lungs
So air is drawn in as the pressure is lower

The reverse happens for exhaling, although normally the elastic recoil of the alveoli and weight of the ribcage means the external intercostal muscles just need to relax in order to produce enough pressure to breathe out
During exercise gas exchange is needed more, so the ventilation rate is increased, meaning more gas is cycled through the lungs

Lung diseases

Pulmonary tuberculosis

Mycobacterium tuberculosis bacteria invade the lungs after being breathed in from droplets in the air
They multiply and form tubercles, lumps of dormant but living bacteria
The white blood cells attack these tubercles, leaving scar tissues that impair breathing (as the scar tissue is thicker) but don't kill all the bacteria
After years the bacteria reactivate and begin multiplying rapidly inside the lung cells, killing them and resisting the immune system
The TB bacteria also spread to other parts of the body and kill cells there
TB has almost been eradicated in the UK and other developed countries due to the presence of a vaccine against it, and also antibiotics which can work against it, however due to antibiotic resistance the treatment is less effective

Asthma

Asthma is an allergic response, where the allergens (eg animal fur) will cause an inflammatory response
This inflammatory response causes the airway to become constricted and so less oxygen can get through

Pulmonary Fibrosis

Caused by inhaling dust or chemicals, usually as a workplace disorder
The foreign bodies become embedded in the lungs and scar tissue forms as the body tries to dislodge them
Scar tissue is thicker and less elastic so the rate of diffusion is decreased

Emphysema

Caused by smoking primarily
Protease enzymes are released into the lungs in order to remove tar deposits, however this destroys the elastic proteins so the alveoli become permanently stretched
This means breathing is more difficult
Also some alveoli may burst and merge together, creating a much larger air space with smaller surface area

The circulatory system

Structure of the heart:

Two atria with thin walls lead down into two ventricles which are much thicker walled through the atrioventricular valves

The valves are held in place by heart tendons so they don't invert

The heart is in two halves:

The left side is the larger side, and deals with pumping oxygenated blood to the body
The right side pumps blood just to the lungs

The heart is made of cardiac muscle which contracts when it gets an electrical signal

As the muscles are constantly working they need a lot of oxygen
The signal powering the heart movement is made by the Atrioventricular node in the right atrium, which causes a wave of excitation to run through the two atria

Once the signal from the atrioventricular node reaches a second node called the sinoatrial node, it is delayed there for a moment before travelling along the Bundle of His to the bottom of the ventricles, where it then travels upwards

The cardiac cycle

This is the sequence of the heart contracting to push blood around the body
It goes in the following order:

Atrial systole
Ventricular systole
Diastole

This ensures that blood always flows from an area of high pressure to an area of low pressure whenever possible

Heart disease

Most heart disease is caused by a blockage in the blood vessels which then impairs blood flow to the heart itself
The blockage starts out as an atheroma, a collection of cholesterol and insoluble lipids on the inside of a blood vessel's wall
This then collects more minerals etc. and becomes a hardened plaque
The artery wall may then swell up and burst, in an aneurism - which can kill
Alternatively, blood cells may become trapped on the plaque and clot up, blocking blood flow

The Immune System

Three lines of defence:

Barriers eg the skin, ear wax, mucus

These block, trap or kill pathogens before they can enter the body

Non specific immune system - phagocytes

Phagocytes kill all pathogens they encounter by absorbing them to form a phagosome, and then releasing enzymes into the phagosome in order to dissolve the foreign cell

Specific immune system - lymphocytes

This system both kills pathogens but also remembers pathogens so they can be killed in future more quickly

Only lymphocyte cells which have been activated will reproduce, so in the first infection there will be only a limited number of matching cells to respond
Subsequent infections can bypass the clonal selection stage so the immune response will start very quickly

Specific immune responses are based on antigens - large molecules on the outside of cells that enable recognition of the cell by the immune system

Some cells will present antibodies on their surface when infected or when they encounter a pathogen, eg. cancer cells or phagocytes
Some pathogens can change their antigens (such as flu) so the

Two forms of specific response:

B-cells (mature in bone marrow)

These produce antibodies which attach to antigens, stopping them in the following ways:

They bind to antigens which interact with body cells which stops the pathogen from infecting a host cell
They bind to toxin proteins and change their shape so they don't work
They clump antigens together which makes them more noticeable to phagocytes and also immobilises cells

T-cells (mature in thymus)

These bind to antigens presented by cells, allowing them to directly kill the cells or become T-helper cells that activate B-cells and T-Killer cells

Vaccination

Vaccines exploit the production of memory cells by inoculating someone against a harmless form of a disease, which promotes the primary immune response without any illness
In the future, if infected, the clonal selection stage can be bypassed and a secondary, stronger immune response will begin immediately

Monoclonal antibodies

These are antibodies produced from one cloned cell - so they all react identically
They are used in science to target specific antigens such as in cancer treatments without hurting neighbouring cells or to react with specific proteins in low concentrations
They are produced in the following process:

Inject a mouse with the antigen needed
Extract the b-cells from the mouse's spleen
Fuse these cells with cancer cells so they will reproduce indefinitely
Test each fused cell for the correct antibody production
Clone the correct cell and collect the antibodies

By the way, I quit

noreply@blogger.com (Alex) — Thu, 16 Feb 2012 10:23:00 +0000

I quit RS more than a month ago. It was over Christmas, and I realised that despite the time off school I had, I was only logging in for weekly events or when I was more or less forcing myself to train.

I mean, the bits I found fun - idling skills while having a chat, questing, the odd bit of slayer - were all either exhausted or I was struck with the feeling that I was a severely second rate player. Quests were the only time in game I really felt like a hero anymore, everything else has become so refined into the "right" way of doing things and everything else is discarded as XP waste. I'm almost out of quests.

I mean, this whole phenomena of skilling efficiently and unefficiently is not new - I've been calculating and scheming on how to get the most bang for my buck when training for years. But the problem is, nowadays the right way to do things all seems to rely on vast sums of gold being available, which it is assumed any competent player will acquire through the "right" ways of making money. The whole build of any modern character seems really defined whereas in the past you were more free to do what you wanted.

But I'm not a luddite. Too many players get to the point where I'm at and complain endlessly about how the game isn't as good as it used to be. And for the record, while I don't think the changes are positive as such, I also think some change is inevitable and am willing to accept it might just be nostalgia on my part. Fair enough, I've been left behind in the wake of the changing game, or I've just grown out of it, or whatever. I didn't bother emptying my bank or anything, I just logged out one day, and when I realised I hadn't logged in again cancelled my subscription.

The fact I felt some anxiety about my members loyalty bonuses vanishing when I cancelled reaffirmed that the fun was gone, really. You used to either be a member, or not be a member, but increasingly now there's this strange place which is above your three quid a month. Well now it's five quid a month. When the price went up and I didn't resubscribe, I knew that was it for me. It's hard to play a game and enjoy the game, and really immerse yourself when you're indirectly paying for ingame benefits. It brings an element of the outside world into it that cheapens the whole thing.

So anyway, an observation or two about what the modern game is now I've extracted myself from it... Pretty much, the core change in the game is that skills are no longer half as valued as they used to be. They used to be the main limiting factor on your progress through the game, and nobody was really expected to get high levels. Sure, you might get a 99 or two if you really enjoyed something, but 1600 total level was something to be proud of. Nowadays, it's much more commonplace for people to get 99 in one or more skills as a matter of course. There never used to be an endgame, you just kept on skilling as and when you wanted, slowly improving your character.

The endgame is the big change. To have a maxed character, in combat at least, is not seen as rare at all. It's something a lot more expected that you will get there, and you'll get there quickly. And once you're there, the game becomes about equipment and the rate at which you make money to pay for that equipment. Combat has a much, much greater emphasis. And of course, if you're maxed in some skills, it's seen as logical that you can max others as well. This is reflected in the arguments over Nomad, or the 91 FM requirement. It's a clash between the players who are like me and cling onto the older ways of thought, who haven't moved with the times, and the new generations of players.

The modern game is much more of a game. I played RS not for the gameyness but the freedom and the exploration. So pretty much, I'm out.

Quick fix for the new RS homepage

noreply@blogger.com (Alex) — Tue, 22 Nov 2011 19:56:00 +0000

Winding down

noreply@blogger.com (Alex) — Fri, 14 Oct 2011 19:12:00 +0000

You may or may not have noticed an extreme lack of RS-related posts recently.

Sorry for that.

Pretty much, the reason is that my school and real life have been stepped up a lot recently. I know in the past I've been inactive, but this time I have the feeling it will be rather more permanent.

So yeah, I'm not closing up entirely, but I'll be going super-extremely inactive as far as RS posts go.

The story of the now #9

noreply@blogger.com (Alex) — Sun, 09 Oct 2011 10:41:00 +0000

Shadow cabinet reshuffle

Ed Milliband has added new members to his Shadow Cabinet after some stepped down to spend more time with their families
The new members are generally younger members of the party, some only having been elected in the last general election
11 of the new members are women
Notably Tom Watson has been promoted to the front bench with a role as deputy chair of the Labour Party, leading for calls for him to resign from the Commons culture committee as he is no longer independent from party policy to the same extent
He has refused to leave, with Ed Miliband backing him, saying it would be "wrong" to take him away from "serving our country"

New colleges announced

New "university technical colleges" have been announced, as specialist centres to teach highly technical subjects
The first of these is being set up at Silverstone race circuit in conjunction with Northampton University
At the same time, more free schools have been announced, with 55 new approvals
These centres will teach students from 14-16, cutting down on academic subjects and focusing on technical studies instead

£75bn cash injection

The Bank of England has added a further £75bn to the UK economy by quantitative easing
This is after £200bn of QE has already been used
Quantitative Easing is when the government buys up banks government bonds, replacing them with cash, in order to give banks more liquid cash to spend
However, using QE has negative impacts on pension yields, as they rely on profits from these bonds in order to make returns to pay the pensions with
Standard & Poors, the credit rating agency, has recently confirmed that the UK's credit rating is stable

The story of the now #8

noreply@blogger.com (Alex) — Sun, 02 Oct 2011 17:13:00 +0000

Protests in New York

Over 700 people were arrested yesterday in New York for protesting the uneven distribution of wealth in the USA
They complain because 1% of the people hold 40% of the wealth
Wall St has been occupied by protesters for 2 weeks now
However the Mayor Bloomberg of New York criticised the protests, saying that the protesters are disrupting the lives of average citizens, however he defends the protesters right to be there
Critics have attacked the protest for having vague goals and no real leadership

Weekly bin collections

The government is putting £250m forward to help councils restore weekly bin collections
More than half of councils run some fortnightly collection
People believe bin collections and public works are core responsibilities of councils

Cameron promises jobs and homes

David Cameron has promised up to 200,000 extra affordable homes and 400,000 new jobs
The homes will be freed up by increasing the "right-to-buy" and releasing government land
However critics compare the strategy to the one employed by Margaret Thatcher, and suggest the government is running out of ideas

Call to axe human rights act

The home secretary has called for the Human Rights Act to be scrapped
This is because it causes problems for the Home Office especially when deporting foreign suspects
However this has caused conflicts between Conservatives and Liberal Democrats

The best addition to citadels

noreply@blogger.com (Alex) — Wed, 28 Sep 2011 21:04:00 +0000

...more detailed tools for the resource system.

Seriously, Jagex have made resources a key thing in working the citadel and keeping it ticking over, why can't they give us more insight and control over who does what. If they're going to be so absolutely necessary, and make the requirements quite tight in terms of organisation and dedication, they really should have more options for how clans can moderate themselves.

I'm saying this after the second week of one particular member getting 700 charcoal, no ores, and making no bars with the mound of charcoal they gather. This of course means that another member has to use their entire cap to clean up after them, or more or less the entire 700 charcoal will go to waste. It's a constant struggle to keep discipline within the clan and make sure that the more unruly members collect the right damned resources.

But, surely the data is there that some interface could be made so clan admins can check out how much each individual member has collected. That would be valuable information as far as deciding promotions goes, as some members contribute each week and go relatively unnoticed. Equally, it means that we can keep an eye on high ranking members and make sure they're not being lax in their duties.

Ideal would be to lock resource plots to members below a certain rank. This would mean that the footsoldiers of the clan would only be able to gather say, stone and timber, whereas the higher ranks (who are generally more reliable) could manage the more complicated task of ores... and also keep on track of stone and timber when the bars are done.

And another useful addition would be the ability to call up the resource stats without visiting the citadel, say through a web interface or an item in game.

The story of the now #7

noreply@blogger.com (Alex) — Sun, 25 Sep 2011 19:54:00 +0000

Saudi women get the vote

Women in Saudi Arabia, a Muslim country that relies heavily on strict Sharia law are getting to vote for the first time
They will also be allowed onto the Shura Council as well as municipal councils, the only elected bodies in the country
Saudi women have less rights than Saudi men in a lot of areas, notably in that women can't drive

Labour promise a £6000 cap on tuition fees

At the Labour conference, the party promised lowering the cap on tuition fees
However, many people are criticising him for allowing any fee rise after Labour MPs were whipped to vote against the rise from £3000 fees
It also works out that the £6000 cap is not actually cheaper for students until they earn over £60000 a year, and as the proposal introduces new taxes at £65000/year the gap in which there is a benefit is very small

Public sector pensions

The government have announced a new plan to save money on public sector pensions
Public sector workers will have to pay more or receive less from their pension from two years time
The pension age will also be raised from 65 to 66 saving £300m
This will save about £900m a year
Unions have threatened a general strike in response to the announcement, with strike ballots being put to members

The story of the now #6

noreply@blogger.com (Alex) — Sun, 18 Sep 2011 18:00:00 +0000

Northern Ireland University Fees

Students in Northern Ireland have found out that they will not have to pay the new £9,000 tuition fees for university courses
The cap will be £3,465 in 2012
Students from elsewhere in the UK will pay higher fees in order to deter "a flood of applications"
This means that English students will have the greatest fees of anybody in the UK

Tax inspector recruitment

2000 tax inspectors will be recruited in order to crack down on tax evasion
The inspectors will be directed to investigate the 350,000 top earners more thoroughly, who each own more than £2.5m
The plan is to raise an extra £7bn of tax by 2015

Gay marriage

The government has declared support for changing the law to allow gay marriage by 2015
At the moment marriage is only for heterosexual relationships, and civil partnership is limited to same-sex relationships
David Cameron backed the drive and included equal marriage in the 2010 manifesto
Religious groups are divided on the issue, some consider it homophobia to prohibit gays from getting married, while others consider it their religious right to deny marriage according to scripture

ROTM

noreply@blogger.com (Alex) — Fri, 16 Sep 2011 16:26:00 +0000

So, continuing my trend of posting about quests well after they've been released because of how long it takes me to complete them, here's my account of Ritual of the Majingos.

Yes, I know, it's Majaraa-something but I can't spell it. Majingos makes them sound like genies anyway, which is what they look like. Well, they do now they're not skeletony anyway.

Yes, ROTM was much anticipated. Yes, it was hyped as providing loads, and loads, and loads of lore and a conclusion to the story While Guthix Sleeps began. And was it a good quest? Yeah. Did it advance the story? Yeah.

But did it conclude the story? No.
And was it... a Grandmaster? No.

ROTM was a lot of fun, with some amazing cinematics and great new tech. And yeah, the final battle was pretty epic of sorts. But the quest felt like it could do with another challenge, another act. The opening act where we introduce the villains, the agility area where the plot thickens, the build up to the climax... and then the fight is upon you, and it feels like there was something more to be done.

Pretty much, the quest is great on paper, but I think it's missing something. I mean, the rewards are telling that perhaps at one point the quest was planned to be something more, as they seem somewhat tacked on in the end. Perhaps there should have been an episode at the Barrows, perhaps there should be some explanation for the Armadyl runes. The Bane Ore was the biggest thing, for me - found only at the ritual cavern, by some coincidence? Perhaps there should have been a short episode of mining some Bane in order to explain the defeat of Lucien better.

The boss battle was also a little lacklustre. Considering you had the power of the Stone to help you out, I think you should have had a chance to fight Lucien directly, even if it wasn't a long or difficult fight. I mean, I've long complained that quests have too difficult boss monsters, and actually I think that this one had a pretty good balance of difficulty, but really? For a Grandmaster, you're fighting some ice titans and demons as a final boss? Hell, it would have been suitably epic still if you fought them all one after another, but the cutscenes here got in the way. They were too long, and split up the fighting too much.

The hype of the quest and the quest itself suggests to me that ROTM was not all it could have been. Perhaps it's just that While Guthix Sleeps is such a high standard, but it didn't hit the same high note as its prequel. In lore terms, it delivers, but the gameplay was just missing something for me. And of course, even in lore terms, it's hardly the end of a series, but the beginning of a whole new one, and who knows how much longer they're going to try and string out the Dragonkin line. It seems like Jagex can never resist the chance to add "one last quest", or in this case a whole lot more quests, rather than letting a storyline end.

The story of the now #5

noreply@blogger.com (Alex) — Sun, 11 Sep 2011 10:23:00 +0000

World Trade Center Memorial

10 years since the attacks on the world trade centre which led to the deaths of nearly 3000 people
Attacks were also carried out on the Pentagon and there was an unsuccessful attempt by hijackers that crashed in Shanksville, which killed all passengers on board
America (especially New York) is on high alert for a followup terrorist attack to disrupt the memorials
The response to the terrorist attack was part of the reason for the war in Iraq and continued operations in Afghanistan
The attacks resulted in racial and religious tensions across the western world, due to the religious motivation behind the attacks

Union calls for "civil disobedience"

The head of the Unite union, Len McCluskey has called for wide-ranging protests against government cuts to public sector jobs
He has called for "direct action" and a "campaign of resistance", calling the cuts an "attack" on pensions and conditions

Sinn Fein running for Irish presidency

Sinn Fein is running for the presidency in the Irish Republic for the first time next month
They are the fourth largest party in Ireland with 10% of the vote, previously having been banned from appearing on TV or the radio as an outlawed party

Bonus XP weekend

noreply@blogger.com (Alex) — Thu, 08 Sep 2011 20:25:00 +0000

So, it starts tomorrow. After a really unproductive day today where I did pengs and nothing else, I'll be starting with a fast farm run and then herblore. Then it's time for firemaking with yews until 83, before I go to the jadinko lair for what is apparently seriously fast XP.

It's a bit annoying really, that they've made a free, fast XP source. I mean, it's of course better for players (or at least easier), but it does mean that firemake is no longer an easy second skill for bonus XP weekends. It's now just as viable to do RC, FM or Agil, and they're all money-neutral.

Ah well. I'm gonna get a ton of levels either way.

Is the class system dead?

noreply@blogger.com (Alex) — Sat, 03 Sep 2011 16:46:00 +0000

The class system was at its height in the Victorian era of strict social etiquette, but now is apparently irrelevant for the most part. Apart from odd cases on either side, such as the super-rich and the very poor, everyone is in the same social group.

One poll showed that 24% of people still identify themselves as working class, with the other 71% of people claiming to be middle class. Nobody in the sample claimed to be upper class. This would suggest that the middle class is indeed expanding, and that even if the class system isn’t entirely gone there’s still a good chance that it is in decline.

However, this result could be based less upon genuine social mobility and more upon the nature of modern workplaces in the UK. The class system was if not appropriate, at least relevant when Britain was a manufacturing powerhouse, however now the office jobs that would previously have qualified someone as middle class are much more common. With fewer jobs in manufacturing, people who are still at a disadvantaged position in society are partway between working and middle class and are left unrecognised.

It is important to be aware of the different backgrounds people have in order to ensure social mobility can happen. If people falsely claim that the class system is abolished, then there will be no effort to counter it, and so some people will end up getting ‘left behind’. It is vital that everyone has as equal opportunity as possible to make a contribution towards society, otherwise those who are disadvantaged will become disinterested and groups will become fragmented.

There is no right answer as to what is the best way to counter social injustice. Education is generally accepted as being important, with some people championing the system of grammar schools. The government’s current policy of creating Free Schools is in part a way to replace grammar and specialist schools. Perhaps the biggest project against social injustice is the concept of the Big Society, proposed extensively by David Cameron as encouraging participation in the community by everyone regardless of social status, volunteering where needed. However, the Big Society has come under a lot of scrutiny and criticism by Labour politicians and the Unite union as being an excuse for the government to evade responsibility for lacking or poorly-funded public services, which are most critical to the least solvent members of society.

Vanstrom Clause

noreply@blogger.com (Alex) — Fri, 02 Sep 2011 17:40:00 +0000

Isn't he tough, eh? A very interesting, and possibly overpowered, quest boss.

In case you didn't catch the drift, I've been doing Branches of Darkmeyer today. Well, actually, I started it as soon as it came out, and got up to the boss battle on Wednesday. It was a very, very good quest. Enjoyable throughout, with a nice new area and interesting dialogue. And a little set of mini-mini quests for bragging rights.

Seriously, well done Jagex. I'm really impressed. The Myreque storyline is one of the biggest and best, and it's showing up for a great finale sometime soon. Perhaps a small quest sometime soon to tide it over and answer a few of the questions raised, before a big bang. The ending of this series could be of WGS-level awesomeness. Perhaps even ROTM-level, we'll find out later this month. (I can't wait!)

The only thing against the quest is it's boss. Because, yet again, I've finished the quest and I'm left facing only the boss two days later. He is allegedly not that tough. A lot of people fighting him died once, perhaps twice or three times (there sure were a lot of graves on release night), and then clicked onto his strategy and nabbed him. They say he's annoying but tell you the tricks of the trade and assume that's enough.

The problem is, it's not. I have no doubt some people did OK against him, and didn't suffer that much damage. I didn't in the end, actually. I died somewhere around twenty times, either getting piled by special attacks in borderline glitches or running out of food in a pretty protracted battle. The boss was really hard, and perhaps could do with a nerf. But in the end when I won, I used under half of the food I was carrying. I had a run where the specials didn't stack, I dodged a lot of darkness, I got some nice gold hits and more importantly than anything, I cracked how to run and avoid the blood bombs (for the most part). In other words, I made a breakthrough but also I got lucky. If I hadn't been "unlucky" previously, I would probably have beat the boss at seven attempts rather than twenty.

I can't use my Nomad argument here, that the boss is unjustified. He's not. This is the first major boss in a very long quest series, and there's a huge amount of lore and justification for Vanstrom being a tough fight. Everything you ever heard said that vampyres are strong, and that Vanstrom is a very powerful vamp.

But like I said, he's still very hard for some players. The blood spell where you get teleported is almost certainly broken for me, and I'm not suffering a lot of lag for that to happen. I get teleported to the middle and then can't move until the attack has already hit or it's too late to avoid damage. It's like I'm frozen or bound by a mage. And then other times, the same attack will fire, but I'll not be teleported and will get away free. I'm pretty sure that's not meant to happen. What I'm even more sure is not meant to happen is that you get that same spell fired multiple times in a row, with no gap between, meaning that on one occasion I got four casts of that chained against me one after the other. It's a miracle I actually survived the first two, let alone getting a scant second to eat and resist another shot and a half.

The multiple casting bug isn't just the blood spell, either. Darkness can often multicast, and while this is actually not so hard to deal with as long as you know what to do, there are occasions where Vanstrom doesn't properly run to the middle, leaving you with almost no warning, or he falls off the side of the screen so you can't see where to face, or the game doesn't register a character's position properly and you take the hit anyway. Sure, learning to turn away and face the camera to the back of Vanstrom's head is a part of the boss's technique, but it seems very hit and miss whether following the correct procedure actually stops you being hit. I mean, I was going to write a bit in this post about how the tech involved in the Darkness attack could be used against bots, but with the amount of grief the attack gave me even when I did everything right, I'd hope Jagex aren't trusting players' accounts to it.

The final gripe is the pathfinding within the boss room. I don't know why, but a lot of the old-school running back on yourself mechanic came into play for this boss battle, and when the aim of the game is to avoid things on the floor, that's deadly.

My internet connection is good and reliable, it doesn't freeze or lag often at all. If you have much latency at all, I feel very sorry for you trying to fight this boss. He's not that hard if you're lucky, but there are occasions where the game can (unfairly) KO you from almost max health, and at nearly any time if you're damaged. Remember the standard advice not to panic-eat, and remember that your stuff is pretty safe. At least he's a pretty fun boss to die to, right? I know I at least enjoyed fighting him today, even if it's cost a lot and I got a bit frustrated, it's a testament to the quest and the core boss design (even if the timings and bugs are squiffy) that he's fun to fight.

The story of the now #4

noreply@blogger.com (Alex) — Mon, 29 Aug 2011 13:00:00 +0000

Libyan conflict

The rebel government, the NTC, has taken control of Tripoli in Libya
After fighting in the capital, Gaddafi's forces have been largely defeated, although the leader himself is currently missing
Remaining soldiers are thought to be barricaded within the town of Sirte, Gaddafi's hometown, under the command of one of Gaddafi's sons
Concern is now emerging for thousands of prisoners, who have not been found and may be abandoned within secret military compounds that are strongly hidden
There is now a medical crisis as people arrive at hospitals fled by the medical staff during the violence
The provisional government is now organising how the seat of power can return to Tripoli and include more eastern leaders

Exam results

Record numbers of exam passes have been recorded for GCSEs this year, with 69.8% of grades being C or above and 23.2% of grades being A or A*
Especially notable is the widening gap between female and male achievement, with 19.6% of boys' entries being As or A*s, compared to 26.5% for girls.

...and the rest

noreply@blogger.com (Alex) — Fri, 26 Aug 2011 10:31:00 +0000

Sorry, little late. I was celebrating and didn't actually come home.

In total, 8 A*s, 4 As, so I'm really really really happy. The As were in English Lang, Graphics, Stats and French, and everything else (Sciences, Maths, Geography, RE and Literature) were A*s.

Thank god for that, my life is somewhat vindicated.

Edexcel

noreply@blogger.com (Alex) — Thu, 25 Aug 2011 06:04:00 +0000

Exam results day

noreply@blogger.com (Alex) — Thu, 25 Aug 2011 04:54:00 +0000

It is currently 5:46 AM. I woke up at around 5:30, and I'm writing this to pass the time and relieve some of the pressure before the magical 6AM mark.

What happens at 6? The first batch of my exam results become available on the internet. For some reason, Edexcel provide their results online, whereas all the other exam boards require you to go in and collect the results personally. The end result of it all is that I'll find about about 5 of my subjects in 11 minutes now, and the rest about three hours later.

I need 10 points to get into sixth form, which I can just about do now. The points are three for an A*, two for an A and one for a B. Nothing for C's or anything else - it's a pretty tough school. Hopefully I'll get an A in Graphics, an A* in Citz and some combination of 5 points from English and Maths, which I'm collecting in 8 minutes now.

Aaaaargh!