B2, C2, P2

Nota:

• collision theory is a theory explaining rate of reactions, the more collisions, the higher the rate of reactions. 3 things affect the collision rate; temperature, the higher the temperature, the more energy the particle has, the faster it will move resulting in more collisions. concentration also increases collision rate as the more particles in a certain space, the more collisions. surface area also affects the collision rate as the larger the surface area, the more area for collisions to happen.

Nota:

• the rate of reaction depends on four things; temperature, concentration, surface area and whether theres a catalyst present.

1. Measuring rate of reaction

   Nota:

   • there are 3 main ways of measuring the rate of reaction; precipitation, change in mass and volume. measuring the time taken for a substance to go cloudy because of a precipitate is one way of measuring the rate of reaction; the faster it goes cloudy, the quicker the rate of reaction. the change in mass is another way; as gas is produced the mass will reduce, meaning the more mass given off over a given amount of time, the faster the rate of reaction. the final method is the volume of gas given off; the more gas given off during a time interval, the faster the rate of reaction.

Nota:

• percentage yield= actual yield/predicted yield

Nota:

• 1)work out the balanced equation 2)underline the sections you need 3)work out the relative formula mass for the parts you want

1. Relative formula mass

   Nota:

   • relative formula mass isnthe sum of all of the relative atomic mass' in a compound.
   1. Calculations

      Nota:

      • to find percentage of an element in a compound: = (atomic mass X number of atoms)/ relative formula mass  all times 100
   2. moles

      Nota:

      • one mole of a substance is the relative formula mass inn grams, so 1 mole = mass(g) / relative formula mass.
2. Relative atomic mass

   Nota:

   • relative atomic mass is the mass in comparison to carbon-12, its usually the same as the mass number. the relative atomic mass is the average mass over all of the stable isotopes of a specific element.

Nota:

• polymers are plastics, covalent bonds form long polymer chains, the strength of the plastic is determined by whether there are bonds holding these chains together, if there's not the plastic can slide and be mis-shapen..

1. Thermosoftening

   Nota:

   • don't have crosslinks so can be melted easily and moulded.
2. Thermosettting

   Nota:

   • have crosslinks to hld the chains together in a solid structure meaning it dosent soften when it gets heated.

Nota:

• metals bond to create giant structures with delocalised electrons from their outer shells moving freely around the substance. because of these delocalised electrons the structure is full of ions and electrons making metals great conductors of electricity. these electrons are also what keeps the structure together; strong electrostatic forces between the positive ions and the negative electrons. this allows metals atoms to be bent and slid over each other, meaning metals can be bent and shaped.

1. Alloys

   Nota:

   • alloys are stronger than regular metals as the different atoms are different sizes so they cannot slide over each other. 

Nota:

• an ion is any atom that has lost or gained an electron and therefore has a non-neutral charge. because of this ions conduct electricity as they have an electrical charge.

1. Ionic bonding

   Nota:

   • ionic bonding is transferring electrons, this happens in the case that one element needs to lose electron and another needs to gain one so the first effectively transfers the electron to the other meaning they can both achieve a full outer shell. ionic compounds all share similar properties andhave a regular lattice that is help togeather by a strong electrostatic force.
2. Covalent bonding

   Nota:

   • covalent bonding is sharing electrons, 2 elements that need to gain electrons will share electrons to create 2 bonded noble gases. each bond provides another electron for 1 of the elements.
   1. Covalent substances

      Nota:

      • covalent substances don't conduct electricity as they do not form ions.(exception- graphite) simple- strong covalent bonds between atoms but weak intermolecular bonds between molecules, because of this the melting and boiling points of the substance is very low because separate molecules can be split with little energy required.giant- similar to giant ionic structures, all of the molecules are bonded with very high intermolecular forces meaning they have a very high melting and boiling point, substances like diamond have 4 rigid bonds making it the hardest natural substance.

1. Atomic number

   Nota:

   • the atomic number is the amount of protons or electrons in an atom
2. Atomic mass

   Nota:

   • the atomic mass is the combined mass of the protons and neutrons.
3. Compounds

   Nota:

   • compounds are chemically bonded elements. carbon and oxygen makes the compound, carbon dioxide.
4. Isotopes

   Nota:

   • an isotope is avariant of an element that has the same atomic number but extra neutrons.

1. Electrolysis of sodium chloride solution
2. Electroplating
3. Extraction of aluminium

1. Acids

   Nota:

   • acids are substances with a ph of less than 7, this ph is caused by h+ ions in the solutuion
   1. H+
   2. Acids reacting with metals

      Nota:

      • metals react with acids to produce salts and hydrogen, only metals that are more reactive than hydrogen will react with the acid, meaning things like copper will not react. different acids produce different salts; hydrochloric acids will produce chlorides, sulphuric acids will produce sulfates, etc...
2. Alkalis

   Nota:

   • alkalis are substances with a ph level of 8 or above, this ph is caused by the oh- ions in the solution.
   1. OH-

Nota:

• activation energy is the energy required for a reaction to take place, if the atoms do not have enough energy to react then the reaction will not take place, a catalyst lowers the activation energy so that the reaction can take place. in industry this reduces the cost as lower temperatures are required and the reaction will take place faster. 

Nota:

• a reversible reaction is a reaction in which the products can react to produce the original reactants.

Nota:

• oxides and hydroxides are bases so thay react with acids to produce salt and water, again the metal decides which type of salt it is.

Nota:

• just like oxides and hydroxides, ammonia is also a base; when ammonia is neutralised with nitric acid it produces ammonium nitrate, an especially good fertilizer.

Nota:

• speed is how fast you're going with no regard to direction.

1. on a graph

   Nota:

   • On a distance time graph the gradient is the speed, if its flat its stationary, straight then its at a steady speed. The steeper the gradient, the faster its going.

Nota:

• Speed and velocity are both how fast you're going, but velocity is speed in a certain direction.

1. acceleration

Nota:

• weight is mass depending on gravity;it is measured in newtons and worked out by the formula:   w=mg weight = mass X gravitational force

Nota:

• mass is the same everywhere, it is the amount of material in an object and is measured in kg.

Nota:

• Gravitational force is the force of attraction between all masses, it depends on the size of the attraction determined by the masss of the object, on Earth its 10ms^2.

Nota:

• A resultant force is the overall force on an object, it can be worked out by adding or subtracting the forces acting on the object. if all forces are equal then the object will remain stationary, if there is any resultant force then it will change its state of rest or motion, meaning if its stationary and theres a resultant force acting on it then it will move. if the object is already moving and there is aresultant force then the object will either speed up or slow down depending on the direction of the resultant force.

1. F = ma

   Nota:

   • the resultant force can also be calculated by mass X acceleration.

Nota:

• Friction always acts in the opposite direction to movement. to travel at a speady speed the resultant force must be equal meaning the force must be equal to the frictional force.

1. Drag/Resistance

   Nota:

   • Drag or resistance is similar to fiction but in air or liquids, as the speed increases the drag increases.
   1. Terminal velocity

      Nota:

      • When an object is moving drag will act upon it decreasing the acceleration until the force acting upon it(gravity or driving force) is equal to the resistance.

Nota:

• The stopping distance is the time it takes from the moment the driver first notices the hazard to the moment the car comes to a complete stop. The overall stopping distance is the thinking distance and the braking distance added together. there are 2 factors that affect the stopping distance, these are the braking distance and the thinking distance.

1. Thinking distance

   Nota:

   • Thinking distance is dependant on the drivers reaction time, the distance however is just how far you travel in this time so therefore the faster you go, the larger the thinking distance. Another factor that impacts this is whether the driver is affected by tiredness, drugs or carelessness.
2. Braking distance

   Nota:

   • The braking distance is the time from when the driver begins braking to when the car is at a complete stop. this can be affected by 4 things: speed, the condition of the brakes, the condition of the tires and how good the grip of the terrain is.

1. work

   Nota:

   • Work is when something is moved, it is calculated by, work done = force(moving the object) X distance. whenever something is moved there is something providing the energy for this movement, this could be fuel, food or electricity. the thing providing the energy is the source of the work. work done is measured in joules.
2. Potential energy

   Nota:

   • Gravitational potential energy is the energy an object has depending on its position in a gravitational field. it is calculated by, gravitational potential energy = mass X height X gravity

Nota:

• Kinetic energy is energy gained by moving, kinetic energy is calculated by, kinetic energy = 1/2 mass X speed^2. so the more something weighs and the faster its going both increase the kinetic energy.

1. Kinetic energy transferred

   Nota:

   • to slow a car down the kinetic energy needs to be lowered, to do this the kinetic energy needs to be transferred into another form of energy, in this case heat through friction so, kinetic energy transferred = work done by brakes.
   1. kinetic energy and work

      Nota:

      • when something fall, the potential energyit had because of its height becomes kinetic energy, so: potential energy lost = kinetic energy gained.

Nota:

• Whenever work is done to change the shape of an elastic, the energy is stored as elastic potential energy. when the force is removed the potential energy is converted into kinetic energy. Any object that will return to its original shape is considered an elastic.

1. Extension

   Nota:

   • when an elastic object is extended, the force that has extende can be worked out by: force = spring constant(depends on the material and will be given) X extension.

Nota:

• power is the rate that work is done, power = work tone/ time       p = e/t         its measured in watts or j/s

1. Power in cars

   Nota:

   • the more powerful a car is, the more energy it transfers from its fuel every second.

Nota:

• momentum= mass X velocity. its a property that moving objects have, the greater the mass and velocity, the higher the momentum. momentum is always the same before and after a collision.

Nota:

• in the case of a car crash the car experiences a massive change in momentum in a very short time, if  human is subjected to this kind of force it could be fatal. in order for the momentum(mass X velocity) to be reduced the speed at which this change happens must be increased. crumple zones do this by increasing the time between the initial hit and the final hit.

1. Crumple zones

   Nota:

   • crumple zones increase the time between the initial hit and the final hit.
2. Side impact bars

   Nota:

   • Side impact bars redirect kinetic energy away from the passengers and towards places better designed for taking hits such as the crumple zones.
3. Seat belts

   Nota:

   • seat belts stretch a little absorbing the kinetic energy, slowing down the time taken for the user to stop and creating elastical potential energy.
4. Air bags

   Nota:

   • Air bags slow you down gradually but more important make it so that the you don't hit your head on hard surfaces.

Nota:

• static is caused by friction, when some materials are rubbed together electrons move from one surface to the other, leaving the surface positive and making the other surface negative, meaning they attract.

Nota:

• current is the electric charge in circuit, current will only flow if there is a voltage(potential difference). it is measured as the amount of charge over time.

Nota:

• resistance increases with temperature, as electricity flows through a resistor, some energy is given off as heat energy. as the heat increases, the ions move more ad it becomes harder for the current to transfer to the next ion, increasing the resistance.

Nota:

• anything that supplies electricity is also supplying energy. whenever a current flows through anything with resistance electrical energy is turned into heat, the more current the more  heat so having a larger voltage will also produce more heat as its pushing more current around.

1. Efficiency

   Nota:

   • efficiency is the amount of energy it wastes compared to the amount it uses. the more energy that's used as useful energy the more efficient something is.
2. Power = energy/time

1. Mains electricity

   Nota:

   • mains electricity is AC(alternating current) but battery suppy is DC(direct current) meaning the current needs to be changed.
   1. Electricity in the home
      1. Fusing
      2. Earthing

         Nota:

         • the earth wire is for the cases when something goes wrong, In these cases the live nad neutral  wires will flow into the earth wire which will take the electricity away.
2. Energy
3. Power

1. Atomic structure

   Nota:

   • the early atom model, the plum pudding, stated that an atom was a positive sphere negative elctrons stuck in it, meaning it has an equal neutral charge throughout, this was disproved by firing alpha particles through gold foil. if this was true and the gold foil was equally neutral, the positive alpha particles would have been slightly deflected. in reality most of the particles went through bring repelled slightly or were deflected massively. this is because the negative electrons sattracted the positive alpha particles but the positive protons repelled them, this meant that depending on where they hit, they either went through and were repelled off at an angle ou the other side or they were reppeled out by the protons.
   1. Parts of an atom

      Nota:

      • protons- positive, mass of 1 neutrons- neutral, mass of 1 electrons- negative, negligible mass 
2. Radiation
   1. Ionising radiation

      Nota:

      • ionising radiation is any form of radiation that creates ions. an ion is an atom which has lost or gained anelectron, it is created when a form of radiation penetrates a material and knocks off electrons.
      1. Alpha

         Nota:

         • Alpha particles are 2 protons and 2 neutrons, the nucleus of a helium atom. they are created when radioactive substances decay producing the particle, in this process the substance's mass goes down by 4 and its atomic mass by 2, creating a new element. they are the largest form of radiation, they are slow and therefore don't penetrate far into any materials, even air. they are strongly ionising, meaning they create a lot of ions, positively charged atoms, when they penetrate a material. 
      2. Beta

         Nota:

         • Beta particles are electrons, they move quite fast and are a lot smaller than alpha particles therefore they penetrate a lot deeper but are less ionising because of their size(electrons will struggle to displace other electrons)when a neutron in the nucleus decays it produces a proton and an electron, the electron is released as beta radiation and the proton joins the nucleus meaning the atom now has a higher atomic number but the same mass, meaning its a different element.
      3. Gamma

         Nota:

         • gamma radiation ismade up of extremely high energy photons, so have no mass or charge. because of this they pass far into materials, making them very weakly ionising as they don't collide with atoms much.
   2. Isotopes

      Nota:

      • isotopes are different forms of the same element, they have the same number of protons and electrons but a different number of neutrons, changing the mass number but not the atomic number. most isotopes are radioactive meaning the nuclei gives out radiation from decaying particles(alpha, beta or gamma)

1. Half life

   Nota:

   • the half life is the time taken for the number of radioactive nuclei to half. the number f radioactive nuclei will decrease as radiation is given out.
2. uses of radiation

   Nota:

   • smoke detectors- alpha, a weak source of alpha radiation is placed between 2 electrodes, causing ionisation and a current to flow between the electrodes. smoke absorbs this radiation meaning the current will stop and the alarm will sound. tracers in medicine- beta or gamma, must have a short half life. using a detector the traces can be followed and monitored as they move around the body, this can be turned into a display that shows where the strongest reading is coming from. an example of this Is using iodine 127 which is radioactive but just like iodine 131 is absorbed by the thyroid gland, it can be traced to see if the ingested sample is absorbed or not. cancer treatment uses gamma radiation, the gamma rays are directed towards a cancer, they kill all living ceels so kill off the cancer along with some healthy cells. as gamma radiation kills all living cells it can be used on food or instruments to kill microbes and keep it clean.
   1. dangers

      Nota:

      • low doses of radiation causes minor ionisation which mutates cells, these cells divide uncontrollably, this is cancer. as beta and gamma can penetrate the skina dn damage delicate organs they are more dangerous from outside the body. as alpha particles are more ionising they do more damage from within the body in a localised area whilst beta and gamma can pass straight out.
      1. safety precautions

         Nota:

         • minimise exposure, avoid contact, keep it as far from the body as possible, avoid looking at it(the eyes are sensitive), store the source in led(it absorbs all 3 types of radiation).

1. Fusion

   Nota:

   • fusion is the joining of two light nuclei, like hydrogen, which will join to create a larger nucleus and a different element. this releases a lot of energy, can be fuelled with just hydrogen and produces little waste. the only problem is that it requires heats of around 10 million degrees C.
2. Fission

   Nota:

   • fission is the splitting up of atomic nuclei, this splitting is exothermic so produces heat which boils water producing steam. a neutron is fired slowly into a uranium or plutonium nucleus, this additional neutron makes it unstable and causes it to split creating 2 or 3 more nuetrons which go off and hit other nucleus' creating an infinitely expanding chain reaction. the heat is created when the nucleus splits but what is also produced is the waste, the rest of the atom that wasn't the 2 or 3 neutrons, in any radioactive substance this is barium and another atom.

1. Photostar

   Nota:

   • clouds of dust and gas collect, the gravitational force between each particle causes the dust and gas to spiral togaether to form a photostar
   1. star

      Nota:

      • gravitational enrgy is converted to heat enrgy, when this heat gets high enough hydrogen nuclei undergo nuclear fusion producing helium nuclei and lots of heat and light.
      1. main sequence star

         Nota:

         • the nuclear fusion has created enough heat to balance the force of gravity, for millions of years its able to consume hydrogen and produce heat. for billions of years after that the star is stable.
         1. Red giant

            Nota:

            • the hydrogen runs out and the star cools turning red, nuclear fusion now turns helium into elements such as iron.
            1. White dwarf

               Nota:

               • the star becomes unstable and ejects its outer gas and dust layer, leaving a dense, solid core.
               1. Black dwarf

                  Nota:

                  • The white dwarf can nolonger produce energy so cools down end eventually dissapears
         2. Red super giant

            Nota:

            • a red super giant is just a bigger red giant.
            1. Supernova

               Nota:

               • the larger red super giant will begin to undergo fusion again, meaning it will glow brightly again and expand and contract, forming harder elements such as iron. the supernova is the explosion in which the star ejects its heavier elements which form new planets and stars, the outer layers of dust and gas are also ejected.
               1. Neutron star

                  Nota:

                  • the neutron star is the dense core left by the supernova.
                  1. Black hole

                     Nota:

                     • if the neutron star is big enough it, the gravitational force will become so strong that it implodes on itself becoming denser and denser. if there it is big enough there is no force stopping it from getting infinitely smaller and infinitely denser. this point is called a singularity and is so dense that not even light can escape the infinite pull of its gravity.

Nota:

• potential difference is voltage it is a force, it pushes the current around a circuit.

Nota:

• Cells make up tissue, which makes up an organ which makes up an organ system.

1. Properties of a cell

   Nota:

   • all cells have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. plant cells have all that plus a cell wall, vacuole and chloroplasts.
2. specialised cells

   Nota:

   • palisade leaf cells- photosynthesis guard cells- open and closered blood cells- carry oxygensperm and egg cells- reproduce

1. Plant structure

   Nota:

   • plants have tissues and organs too.
2. Photosynthesis

   Nota:

   • Carbon dioxide + water => glucose + oxygen (must have sunlight and chlorophyll) To create glucose for cellular respiiration, Oxygen is the bi-product.
   1. Limiting factors

      Nota:

      • factors- sunlight, water and carbon dioxide. sunlight and heat- optimum temp 35" too hot- the enzymes, chloroplasts, get denatured and cannot aid the reaction. too cold- the reactants dont have enough energy so the reaction is very slow.                                                                                                                                                                              

Nota:

• The distribution of an organism depends on environmental factors, such as: temp, water, oxygen, carbon dioxide, nutrients, light.

1. Always consider reliability and validity

Nota:

• exercise increases the heart rate.

1. muscles

   Nota:

   • Muscle cells use oxygen to release energy from glucose. this creates carbon dioxide which needs to be carried out in the blood, meaning heart rate increased.
   1. glucose

      Nota:

      • glucose, from sugars, is needed for the muscle cells to create energy. glucose is stored as glycogen which is stored in the liver, but each muscle has its own store. when a muscle needs more glucose it releases the hormone glucagon because the GLUCose is All  GONe.

Nota:

• embryonic stem cells are celss that can turn into any type of cell. stem cells are undifferentiated cells, meaning they have not been allocated a specialisation. as they have the potential to turn into any cell they want meaning they have the potential to cure many things.

1. Medical potential

   Nota:

   • stem cells from bone marrow are already used to creat new blood cells when people have blood diseases but because of controversy the far more versatile embryonic stem cells are not widely used even though they could be used to create glands and heart tissue even nerve cells for spinal injuries and paralysis.
   1. Opposition

      Nota:

      • Many people are against it as it is the potential of human life.  people believe that it is not sustainable and that scientists should focus on curing a disease than individual patients.

Nota:

• Genetic disorders are caused by dominant or recessive allelles. genetic screenings can detect genetic disorders but there are many argumants for and against this.

1. genetic screening
   1. For

      Nota:

      • it will stop suffering there are limits- laws prevent things from going "TOO" far during IVF most embryos are destroyed anyway treating disorders will cost more money in the long run.
   2. Against

      Nota:

      • its very subjective as people can basically decide every characteristic they want in a child- not natural rejected embryos are destroyed it implies that people with genetic problems are undesirable its expensive.

1. Extinction

   Nota:

   • extinction happens when a species cant evolve quick enough to survive-  the changing environment predators disease competition for food or because of a catastrophic event that wipes out an entire species.      
2. Speciation

   Nota:

   • speciation is when a population of a certain species evolve separately to the rest because of environment, predators.. and create an entirely new species.
3. what makes it a new species?

   Nota:

   • a specie is a group of similar organisms that can breed to crete fertile offspring. when something evolves and can no longer breedto produce fertile offspring speciation has taken place and that is a new specie.

Nota:

• Fossils are the remains of plants and animals. as teeth, bones, shell... eventually decay they are replaced by minerals, the actual fossil, which is shaped like the original "hard part" when things are preserved I clay and soft things it will decay and the clay will harden leaving a cast. amber- in amber there is no oxygen or moisture so things cant decay meaning when it solidified anything inside is fully formed.

Nota:

• every cell has 46 chromosomes, 22 matched pairs and 1 either XX or XY pair(XX female XY male)

1. Sperm and eggs

   Nota:

   • sperm cells are either X or Y (50/50) and eggs are always X.

Nota:

• deoxyribonucleic acid makes up chromosomes

1. Genes

   Nota:

   • Genes are found in DNA, they contain the instructions to create a specific protein, this is done by stringing together the 20 different amino acids in different orders.
   1. Cells create protein, depending on the DNA and genes

Nota:

• natural catalysts speed up reactions, they are not used up in the reaction. they can split or create substances and are usually only shaped so that 1 reaction can take place using that catalyst.

1. Enzymes in digestion

   Nota:

   • the process of digestion depends entirely on enzymes to break down large jmolecules nto smaller ones.
   1. Lipase

      Nota:

      • lipase converts lipids into glycerol and fatty acids. it is created in the pancreas and small intestine.
   2. Amylase

      Nota:

      • amylase is one of the main enzyme involved in digestion it converts starch into sugars, it is produced in pancreas, small intestite and as salivar.
   3. protease

      Nota:

      • protease converts protein into amino acids.it is produced in the stomach, pancreas and small intestine. 
   4. Bile

      Nota:

      • Bile is produced in the liver and is an alkaline that neutralizes the stomach acids so that enzymes can work efficiently. it also breaks down fat so that lipase can break it convert it easier (larger surface area).
2. Enzymes in respiration
   1. RESPIRATION IS RELEASING ENERGY THROUGH THE BREAKDOWN OF GLUCOSE
      1. THIS HAPPENS IN EVRY CELL IN EVERY LIVING THING.
   2. Aerobic

      Nota:

      • Respiration using oxygen. its always happening in order to maintain body heat, contract muscles.
      1. GLUCOSE + OXYGEN => CARBON DIOXIDE + WATER + ENERGY
   3. Aenerobic

      Nota:

      • used when the body dosent have enough oxygen for aerobic, basically a backup. it gives a short burst of energy
      1. Oxygen debt

         Nota:

         • when your body cant keep up with the demand for oxygen to create energy you use anaerobic and get an oxygen debt. you will need oxygen,this will oxidise all of the harmful lactic acid produced into carbon dioxide and water.
      2. GLUCOSE => ENERGY + LACTIC ACID
3. NATURAL PROTEIN CATALYST

   Nota:

   • in the human body an enzymes optimum catalysing temperature is 37" (body temp) optimum ph is usually neutral (7)
4. Uses for enzymes

   Nota:

   • the digesting enzymes are used in detergents to break down stains. they're used in baby foods to basically pre-digest the food.
   1. Industry

      Nota:

      • used to speed up reactions advantages- they're specific energy saving as there is no need for pressurising machines and high temperatures. long term cheaper as its only the initial cost. environmentally friendly.    
      1. advantages
      2. disadvantages

         Nota:

         • allergies to enzymes very susceptible to being denatured from a small increase in temp and contamination in an industrial environment. expensive to produce  

Nota:

• -Respiration -Making:  -Cell walls-Proteins-Stored as glucose to be used in the winter when photosynthesis cannot take place.

Nota:

• the net movement of particles through a partially permeable membrane along a concentration gradient.

1. mitosis

   Nota:

   • Mitosis takes place with every cell to create new cells in order to grow or repair.1)The 46 chromosomes in a cell duplicate to form 46 chromosomes which each consists of 2 chromatids bound by a centromere. 2)The chromosomes move to the centre of the cell, the 2 chromatids of each chromosome split at the centromere, creating 92 chromosomes. 46 chromosomes go to either side of the cell.  3The cell splits creating 2 cells each with 46 chromosomes, they are both identical to the original cell.
2. Meiosis

   Nota:

   • meiosis is cell division used in reproduction, it creates 4 daughter cells that each have 23 chromosomes. 1) 23 chromosomes from each parent combine to make a cell with 46 chromosomes. 2)These 46 chromosones duplicate to form 46 chromosomes that consist of 2 sister chromatids bound with a centromere. 3)The chromosomes pair with another chromosome from the other parent to form 23  homologous pairs, each homologous pair consists of 2 chromosomes (each are 2 sister chromatids)4)These 23 homologous pairs line up and exchange genetic material.5)These 23 homologous pairs split in the cell and form 46 chromosomes which have a mix of genetic material, half at each side of the cells.6)The cell splits and forms two cells with 23 chromosomes with a mix of genes.27)In each cell, the centromeres connecting the chromatids of the 23 chromosomes split producing 46 chromosomes at either side of the cell. 8)Both cell splits producing, in total, 4 daughter cells with 23 chromosomes each.