Questions 1 HKALE 1990 Biology Paper II 1 HKALE 1993 Biology Paper II 1 HKALE 1996 Biology Paper II 1 HKALE 1999 Biology Paper II 1 Suggested Solution 3 HKALE 1990 Biology Paper II 3 HKALE 1993 Biology Paper II 4 HKALE 1996 Biology Paper II 6 Questions HKALE 1990 Biology Paper II 5. (b) Discuss the importance of carbohydrates‚ lipids‚ proteins and roughage in the human diet. (8 marks) Suggested Solution… HKALE 1993 Biology Paper II 6. Based upon its properties‚ discuss
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the heat transfer occur: from hot water to cold‚ or from cold water to hot? Answer: The heat transferred from hot water to cold water is due to their potential (temperature) difference. * c. What quantity of heat was transferred from one sample to the other? Answer: Here heat transfer from hot water to cold water. Mass of hot water (m) = 200g Initial temperature (T) = 80˚C Finial temperature (T2) = 60˚C Specific heat of water (s) = 4.18 J/g˚C ∆T=(60-80)℃ = - 20˚C Heat transfer
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of 23 printed pages and 1 blank page. SPA SJF4655/CGW T45720/3 © OCR 2008 [H/103/4250] OCR is an exempt Charity [Turn over 2 EQUATIONS efficiency = useful energy output total energy input energy = mass × specific heat capacity × temperature change energy = mass × specific latent heat fuel energy input = waste energy output + electrical energy output power = voltage × current energy supplied = power × time energy (kilowatt hours) = power (kW) × time (h) wave speed = frequency × wavelength ©
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of photosynthesis requires water in order to create glucose. The fact that water has an unusually high specific heat capacity makes it a very useful substance for living organisms. Water does not change temperature very easily and therefore minimizes fluctuations in temperature in cells and creates a remarkably constant sea temperature for aquatic organisms. Water has a high latent heat of vaporisation which means that when animals sweat and plants transpire water‚ takes energy from the organism
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Discuss why hydrogen bonding is essential for life Throughout biochemistry there are many bonds without which life as it is on earth today would not be possible. One of the most important bonds of these is the hydrogen bond‚ a weak chemical bond that is present in essential biological molecules such as water and polypeptides. A hydrogen bond is defined by Campbell and Reece as occurring when a hydrogen atom is covalently bonded to an electronegative atom but attracted to another electronegative
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energy. Planning We will be using 6 different fuels to heat up 100ml of water‚ and find out the changes of the temperature. We will measure the temperatures of the water before and after the experiment. We will burn heat the water for exactly 2 minutes‚ and check the changes in temperature. The change in temperature will allow us to work out the energy given off the fuel by using this formula: Mass of water x 4.2 (water’s specific heat capacity) x temperature change = energy transferred from the fuel
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significant figures! ] SHOW YOUR WORK to get full credit. 1) Number of moles: 2) Pressure of each gas: 2. [ out of 16 pts ] When 11.1 g of lead reacts with 3.81 L of oxygen gas‚ measured at 1.00 atm and 25.0°C‚ 11.8 kJ of heat is released at constant pressure. What is ∆H° for this reaction? (R = 0.0821 L • atm/(K • mol)) 2Pb(s) + O2(g) → 2PbO(s) [ do not neglect significant figures! ] SHOW YOUR WORK to get full credit. 1) Determine
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This experiment will test the suggestion that the enthalpy change between a metal and a solution of a salt is related to the relative position of the two metals in the reactivity. Presumably the further apart in the series the bigger the enthalpy change will be. The experiment is as follows‚ 1) Zn(s) + CuSO4(aq) ZnSO4(aq) + Cu(s) 2) Zn(s) + Pb(NO3)2(aq) Zn(NO3)2 (aq) + Pb(s) Both of the solutions will be in 1mol.dm-3 Apparatus: Distilled Water Polystyrene Cup
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needs for running‚ talking‚ and thinking comes from the food you eat. Energy content is the amount of heat produced by the burning of 1 gram of a substance‚ and is measured in joules per gram (J/g). Usually‚ fat-rich foods like peanuts and cashews provide more energy than just carbohydrates like marshmallows. You can determine the energy content by burning a portion of food and capturing the heat released to a known mass of water in a calorimeter. If you measure the initial and final temperatures
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Enthalpy change‚ ΔH‚ is defined as the heat output of a system as it goes through a reaction under constant pressure. It is an important aspect of thermochemistry‚ which is the study of energy changes during a chemical or physical reaction . When we calculate enthalpy change‚ we always assume that the pressure is constant. We are able to calculate enthalpy change numerous ways‚ notably by the increase in heat‚ Q‚ given by an exothermic reaction or the heat absorbed by an endothermic reaction. To
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