GCSE SCIENCE past paper notes

Notes: Question 1. 1  Nucleus = Eurkayotic cell / Permanent Vacuole = Plant cells only /  Plasma = Prokaryotic cell 1.2 tick the bottom box Vacuole, ribosme, cell wall 1.3  The student should turn the fine focusing knob until the cells are in focus 1.4 Rotate the objective lens to a higher power 1.5 Write the equation -magnification = image size / real size  convert  112mm to 112 000 um magnification = 112 000/280 answer = 400   Question 2.1 a non-communicable disease is not spread from person to person. this is because it is not caused by a pathogen 2.2 CHD can cause a heart attack by restricting blood flow through the artery. This means that less oxygen can reach the heart muscle. This means that the heart cells cannot respire enough. 2.3 Obesity and high cholesterol can cause fatty deposits and CHD. Smoking and high salt diet can cause high blood pressure which increases stress on fatty deposits leading to heart attacks. Genetics can affect how easily you can develop CHD Question 3.1 6CO2 + 6H2O -----> C6H12O6 + 6O2 3.2 Endothermic 3.3 measure the volume of gas released and measure with an increased length of time 3.4 If the pondweed is at a different temperature then it will have a different rate of photosynthesis this is because temperature affects the rate of photosynthesis and photosynthesis is controlled by enzymes. 3.5  L ∝ 1/5 squared = l ∝1/25     L  ∝ 1/10 squared = L  ∝ 1/100. As the distance doubles, the light intensity is quartered.  3.6 If you double 20 it would be 40 that would predict  2 bubbles. This is because there is very little light for photosynthesis. 3.7  To vary the carbon dioxide concentration, we would have to use different concentrations of sodium hydrogencarbonate solution. The other two control variables are the distance from the light source and the temperature for the solution. Question 4.1 This is because the carrots had different starting masses 4.2 watch a video on that question 4.3  watch a video 4.4 The carrots mass has decreased this is due to loss of water by osmosis. As the concentration of sugar is greater than the concentration of sugar solution inside the carrot. It also requires a partially permeable membrane. 4.5 This is because the high temperature damaged the partially permeable  membrane  Question5.1 not everyone would go to the doctor  5.2 percentage change = change / original x 100 1939/2030 x 100 = 95 .5 % 5.4 After the measles exposure, the concentration of antibodies produced was much higher than after the vaccine. Also, the antibodies were created much sooner than after the vaccine where there was a lag. Antibodies are made by white blood cells. After the vaccine, the white blood cells have remember how to make the specific measles antibodies using memory cells. This means the response can be immediate, large and specific. Question 6. 1 stem cells are found in the meristem  6.2  to produce large numbers of identical plants 6.3  6 x 10 to the power of - 12 6.5 Stage 1 - cell grows and replicates the DNA and the other organelles Stage 2 - The nucleus divides and one set of chromosomes move to each part of the cell. stage 3 - Cell membrane divides to form two identical cells My answers:                  

Notes: Question 1.1 chlorine 1.2 copper is less reactive than hydrogen 1.3) 0.6 + 1.2 + 2.4 + 3.06 = 7.26 1.4 watch a yt on to how to answer that question 7.26 / 4 = 1.815  answer = 1.8mg 1.5 0.05 x 300 = 15g still watch a yt video for that question 2.2 sodium loses one electron. sodium now has a negative ion. chlorine gains one electron. chlorine now has a positive ion 2.3 watch a yt video for that question 2.1 difference = sodium has 1 electron in their outer shell, chlorine has seven electrons in its outer shell  similarity = they both have incomplete outer shells Question 3) The student should use sulphuric acid as this will make sulphate instead of the hydrochloric acid which makes chlorides. they should make copper carbonate instead. The student should add carbonate until no more reacts. they should then filter this to remove the excess solid. They should finally, heat gently until nearly evaporated and left to slowly crystallise.    Question 4.1  g (make sure it is lower case g) 4.2  watch a yt to answer that question 4.3 18 4.4  2AI + 3Br2 ---> 2AIBr3 4.5 Chlorine is more reactive than bromine because it is more reactive in group 7 which means it has fewer energy levels so therefore chlorine can gain an electron more easily. 5.1 Diamond had a low melting point because each carbon atom is joined to four other carbon atoms by covalent bonds  a large amount of energy is needed to overcome the many strong covalent bonds. it has a giant covalent structure  5.2 If you dissolve sodium chloride in water, the ionic lattice breaks apart and the sodium and chloride ions are free to move around. 5.3 watch a YT video Question 6.1  CaO and CO2 6.2  12 + (3 x 16) = 60 197 - 60 = 137  relative atomic mass = 137 metal = barium 6.3  watch a yt video 6.4   8.1 hydrogen 8.2 filtration 8.3  8.4 iron is being reduced (Fe 3+) Fe 3+   +  3e(-)  --->  Fe reduction is the gain of electrons         my answers:  

Notes: Questions 1.2  positive charge comes from the protons. Every atom of the element has the same number of protons. so same total positive charge 1.3 ( 300,000,00/100) x 7 = 21,000,000 answer : 21,000,00 m/s 1.4  6 x 2.5 x 10 to the power of -11 = 1.5 x 10 to the power of - 10 answer = 1.5 x 10 to the power of - 10 Question 2.1 Place the stone on the top pan balance and measure its mass. Fill the displacement can until the water is level with the bottom of the pipe. Place a measuring cylinder under the pipe ready to collect the displaced water. Carefully drop the stone into the can and wait until no more water runs into the cylinder. Measure the volume of the displaced water. Use the measurements to calculate the density of the stone. 2.2 watch a yt video 2.3 Uncertainty =  1/2 x range uncertainty = 1/2 x ( 1120 - 960) uncertainty = 1/2 x 160 answer: 80 Question 3) 3.1 they move in random directions. they move at a range of different speeds. 3.2 the speed of the particles would increase 3.3 if the temperature increases, the pressure would also increase, so it could explode. 3.4   0.1 3.5   p = 2.25 x 0.25 p = 0.56 answer: 27 3.6  the volume of air increases Question 4) 4.1    2 charged particles and 2 neutral particles 4.2    it is the type of radiation with a negative charge 4.3      it has a very long range in air 4.4  The risk associated with Caesium hasn't decreased by much as Caesium has a long life. The risk associated with Iondine has decreased by a large amount as iodine has a small half life. 4.5     5 x 30 = 150 150 +  1986 = 2136 answer: 2136 Question 5) 5.1    The wall has two layers. cavity wall insulation has low thermal conductivity  so less energy is transferred by conduction.  5.2    T =  20.8 - 17.4 / 2 answer: 19.1 5.3  Chemical energy store of the fuel decreases thermal energy store of the water increases  thermal energy store of the air increases 5.4 E = 15 000 000  (J) T =  600 (s) p  = 15 000 000 / 600 p =  25 000 (w) answer: 25 000 Question 6) 6.1  watch a yt video 6.2      i to the power of 1  =  i to the power of 2 + i to the power of 3 i to the power of 2 =  i to the power of 3 6.3   p = i to the power of  2   x   12 3 = i to the power of 2  x 12 i = square root (  3 /12) i = 0.5 Q = 0.5 x 60 = 30 Q total = 60 answer: 60 6.4 my answer:

Notes: Question 1) Factor       /         Biotic        /       Abiotic Diseases       ✓ Herbivores   ✓ Temperature                          ✓ Water                                     ✓ 1.2  Low light intensity under the tree. less photosynthesis  under the tree which produces more glucose and proteins 1.3   quadrat  light meter 1.4      1.5m to the power of 2 1.5   to keep the light intensity as similar as possible 1.6    repeat investigation around the tree 1.7   daisy 1.8   as light intensity increased so did the percentage of plants. 1.9    Factor -   lack of water reason -  because the leaves are stopping the rain. Question 2 ) Do not prescribe fluoroquinolone. Because they will get better due  to the body's normal immune system Do not prescribe to antibiotics for viral infections, because antibiotics do not kill viruses. If you do prescribe fluoroquinolone make sure the patient finishes the course. because any bacteria left may develop resistance, survive and reproduce rapidly. Only prescribe fluoroquinolone if the patient has a new strain. Because routine use would lead to an increase in restraint bacteria. Doctors and nurses in the hospital should be using antibacterial hand wash between  each patient or disinfectant to clean wards, to kill bacteria.   Question 3 ) 3.1  They survive in high temperatures. They survive where it is acidic 3.2    C 3.3  because it has activity at high temperature  3.4   Archea - primitive bacteria Prokayota  -  modern bacteria Eukaryota -  includes plants and animals 3.5  these microorganisms live in extreme conditions. Question 4 ) 4.1   p ( synapse) Q ( relay neurone) 4.2   the neurone - electrical impulse synapse - movement of chemical transmitters 4.3  the impulse has to travel to the brain and back. 4.4    120   = 1.6 / time answer: 13 4.5   As age increases the time for the muscle to contract increase at an increasing rate. Question 5 ) Question 6 ) Question 7) my answers:

Notes: Question 1)  1.1 condenses 1.2 the fractions have different boiling points 1.3  propane 1.4 CnH2n + 2 1.5   CH4 + 2 O2 ----> CO2 + 2 H2O 1.6 Bromine water 1.7   To assess the environmental impact of the stages in the life of a product   Question 2) 2.1 methane 2.2  rising sea levels  agricultural problems 2.3    6.0/ 4.1  x 0.0235 = 0.0344kg 2.4 use less plastic 2.5 Question 3) 3.1  16 3.2   advantage -  more accurate result disadvantage -  takes a longer time, more energy needed 3.3   pure water -no  dissolved solids portable water -  has dissolved solids 3.4  groundwater - filtered and sterilised seawater - distilled  3.5   2.2/100 x 6.50 answer: 0.143g   Question 4) Question 5) Question 6)   my answer:  

Notes: question 1) 1.1 Its acceleration would decrease to zero. The resultant force on it would decrease to zero. 1.2  move the second light gate closer to the first 1.3 Mistake -  1.26667 m/s to the power of 2 is wrong Correction -  give values to 2 significant figures Mistake -  6.7 m/s to the power of 2 is wrong Correction - discard the anomalous result and recalculate the mean 1.4   resultant force is directly proportional to acceleration 1.5  look at the answers 1.6  as mass increases, acceleration decreases question 2) 2.1   tick the first box 2.2     permanent magnet has no effect on the aluminium iron is attracted to the permanent magnet only the permanent magnet can be repelled by the permanent magnet 2.3 Question 3) 3.1 momentum = mass x velocity 3.2    200 = m x 3.2  m = 200 / 3.2 answer: 63 3.3 question 4) question 5) question 6 ) question 7) my answers:  

Notes: Question 1) 1.1  B 1.2   right atrium  1.3   foxgloves 1.4  x = 2800 /52 = 53.846153 answer: 54 1.5 Question 2) 2.1 amylase 2.2  partially pumping testing - small intestine Water in a test tube - blood 2.3  Starch - Iodine solution Sugar -  Benedicts solution 2.4 enzymes had not started to work 2.5  enzyme digested not all the starch was broken down 2.6 sugar molecules formed are small enough to pass though tubing  Question 3) 3.1  opened and closed the tap 3.2 air bubble moves further so resolution is improved 3.3  66/5 x 0.8 answer: 10.56 3.4 3.5 3.6   no photosynthesis the stomata will close as  no carbon dioxide needed no transpiration  Question 4 ) Question 5) my answers:

Notes: Question 1) 1.1  Ca, Mg, Zn, Cu 1.2   Concentration mass 1.3  the type of element 1.4 Berrylium is less reactive reason - the greater attraction between the nucleus and outer electrons  1.5  50 / 1000 = 0.05 0.05 / 3.2 = 64 answer: 64 Question 2) 2.1   (aq) 2.2  HNO3 2.3  colour in nitric acid - red colour in ammonia solution - purple 2.4    D 2.5    3 x 16 = 48 48/80 x 100 = 60 answer: 60 2.6 Question 3) 3.1 3.2  ( 800 - 300) = 500 (kJ) answer: 500 3.3 look at the answers 3.4  (4 x 463) + (2 x 138)  ( 1,852 + 496) = 2348 ( 2128 - 2348) = - 220 answer: (-) 220 (KJ) Question 4 ) 4.1 atomic weight 4.2  left gaps 4.3  weak forces between the molecules. so little energy is required to break the forces between molecules. 4.4  The molecules get larger going down the group  So the forces between the molecules increases  4.5 2,8 2 in the first shell 8 in the second shell 4.6   1/40 x 6.02 x 10 to the power of 23 Question 5 )  5.1 metal is too reactive to be extracted using carbon 5.2     1)  aluminium oxide 2)  cryolite 5.3   Half equation at negative electrode  Cu 2+   + 2e-   ---> Cu half equation at positive electrode  2 CI-   ---> Cl 2 + 2e- 5.4    1) Volume of the solution was different 2)  copper removed when drying electrode 5.5  (1.8 / 10) = 0.18 0.18 x 24 x 60 0.18 x 1440  answer: 259 mg 5.6   4.75 5.7    2.0 / 10  = 0.2 0.2g/hour  Question 6) 6.1   2 Na + Cl2  ----> 2NaCl 6.2  Before reaction - silver solid during reaction - yellow flame After reaction - white solid 6.3  Sodium has fewer energy levels. The outer electron is closer to the nucleu.s So greater attraction between nucleus and outer electron.  So an outer electron is less easily lost. 6.4  my answers:

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