Q1. Fresh milk is a mixture of compounds including lipid, protein and about 5% lactose sugar.

Transcription

1 Q1. Fresh milk is a mixture of compounds including lipid, protein and about 5% lactose sugar. Lactose must be digested by the enzyme lactase, before the products can be absorbed. Lactase can be added to fresh milk to pre-digest the lactose. This makes lactose-free milk, which is suitable for people who do not produce enough lactase of their own. A student investigated the effect of changing ph and temperature on the digestion of lactose in milk. The results are shown in Tables 1 and 2. Table 1 Effect of ph Table 2 Effect of temperature ph Time taken to digest lactose in minutes Temperature in C Time taken to digest lactose in minutes No digestion (a) The label on a carton of lactose-free milk states: Lactase is normally produced in the stomach of mammals. The results in Table 1 suggest that this statement is not true. Explain how Page 1 of 26

2 (b) Explain, as fully as you can, the results shown in Table (3) (c) Bile is produced in the liver and is released into the small intestine. Bile helps the digestion of lipid in the milk. Describe how (Total 7 marks) Q2. (a) Use words from the box to complete the equation for aerobic respiration. alcohol glucose lactic acid water... + oxygen carbon dioxide +... (+ energy) Page 2 of 26

3 (b) Some students investigated the effect of temperature on the rate of aerobic respiration in earthworms. The diagram shows the apparatus the students used. When the tap is closed, the bead of liquid moves to the left as the earthworms take in oxygen. The students put the test tube into a water bath at 20 C for 10 minutes. They left the tap open during this time. Why did the students put the test tube in the water bath at 20 C for 10 minutes? Tick ( ) one box. Because the air contains more oxygen at 20 C. Because the air contains less carbon dioxide at 20 C. So the earthworms body temperature would change to 20 C. (c) The students then: closed the tap started a stopwatch recorded the position of the bead of liquid every 2 minutes for 10 minutes repeated the experiment at 10 C. The graph shows the students results. Page 3 of 26

4 Volume of oxygen taken in =... mm 3 Time in minutes (i) How much oxygen did the earthworms take in during the 10 minutes at 20 C? Use information from the graph to work out your answer. The earthworms took in this volume of oxygen in 10 minutes. Use your answer from part (c)(i) to calculate how much oxygen the earthworms took in each minute. Volume of oxygen taken in =... mm 3 per minute (iii) The earthworms took in less oxygen each minute at 10 C than they took in at 20 C. Explain why. Page 4 of 26

5 (d) When drawing the line on the graph for the experiment at 10 C, the students ignored the reading at 8 minutes. (i) Suggest why they ignored the reading at 8 minutes. One student suggested they should repeat the experiment twice more at each temperature. How would repeating the experiment improve the investigation? (Total 10 marks) Q3. The diagram shows some of the cell divisions that occur during human reproduction. (a) (i) Name the type of cell division that produces cell D from cell B. Which organ in the male body produces cell C from cell A? Page 5 of 26

6 (b) (i) Cells A and B each contain 46 chromosomes. How many chromosomes would there be in the nucleus of cell C? Why is it important that cell C has this number of chromosomes? (Total 5 marks) Q4. (a) Mr and Mrs Smith both have a history of cystic fibrosis in their families. Neither of them has cystic fibrosis. Mr and Mrs Smith are concerned that they may have a child with cystic fibrosis. Use a genetic diagram to show how they could have a child with cystic fibrosis. Use the symbol A for the dominant allele and the symbol a for the recessive allele. (3) Page 6 of 26

7 (b) Mr and Mrs Smith decided to visit a genetic counsellor who discussed embryo screening. Read the information which they received from the genetic counsellor. Five eggs will be removed from Mrs Smith's ovary while she is under an anaesthetic. The eggs will be fertilised in a dish using Mr Smith s sperm cells. The embryos will be grown in the dish until each embryo has about thirty cells. One cell will be removed from each embryo and tested for cystic fibrosis. A suitable embryo will be placed into Mrs Smith s uterus and she may become pregnant. Any unsuitable embryos will be destroyed. (i) Suggest why it is helpful to take five eggs from the ovary and not just one egg. Evaluate the use of embryo screening in this case. Remember to give a conclusion to your evaluation. (4) Page 7 of 26

8 (c) In someone who has cystic fibrosis the person s mucus becomes thick. The diagram shows how, in a healthy person, cells at the lung surface move chloride ions into the mucus surrounding the air passages. The movement of chloride ions causes water to pass out of the cells into the mucus. Explain why (3) (Total 11 marks) Q5. Evidence for early life comes from fossils. (a) (i) What is a fossil? Page 8 of 26

9 We do not have a complete fossil record from the beginning of life on Earth. Suggest two reasons why. (b) The sea erodes cliffs at the coast. Some cliffs have layers of rocks. The diagram shows a cliff at the coast. The cliff has four layers of rock, A, B, C and D, that contain fossils. Adrian Bicker / Science Photo Library Which layer of rock, A, B, C or D, is likely to contain the oldest fossils? Write your answer in the box. Explain your answer Page 9 of 26

10 (c) The fossil record shows that some animals have become extinct. Give three possible reasons why animals become extinct (3) (Total 9 marks) Q6. Oil rigs are used to drill for crude oil. Digital Vision/Photodisc (a) Drill heads are made from steel. Steel is an alloy. Explain why alloys are harder than pure metals (3) Page 10 of 26

11 (b) Drill heads also contain diamonds. Describe, as fully as you can, the structure and bonding in diamond (4) (c) Polymers are produced from crude oil. Describe the structure and bonding in a thermosoftening polymer and explain why thermosoftening polymers melt when heated (4) (Total 11 marks) Page 11 of 26

12 Q7. Printed pictures can be made using etchings. Eduardo Jose Bernardino/iStock An etching can be made when a sheet of brass reacts with iron chloride solution. (a) Brass is a mixture of two metals, copper and zinc. (i) A mixture of two metals is called.... Draw a ring around the correct answer to complete the sentence. Copper and zinc atoms are different sizes. harder This makes brass more flexible than the pure metals. softer (b) Iron chloride has the formula FeCl 3 Relative atomic masses (A r ): Cl = 35.5; Fe = 56. (i) Calculate the relative formula mass (M r ) of iron chloride (FeCl 3 ). Relative formula mass (M r ) of iron chloride =... Page 12 of 26

13 Calculate the percentage of iron in iron chloride (FeCl 3 ). Percentage of iron in iron chloride =...% (Total 6 marks) Q8. Hand warmers use chemical reactions. (a) The table shows temperature changes for chemical reactions A, B and C. Reaction Starting temperature in C Final temperature in C Change in temperature in C A B C What is the final temperature for reaction B? Write your answer in the table. (b) (i) What name is given to reactions that heat the surroundings?... Which reaction, A, B or C, would be best to use in a hand warmer? Reaction Give a reason why you chose this reaction Page 13 of 26

14 (c) A student added water to some anhydrous copper sulfate. The equation for the reaction is shown. anhydrous copper sulfate + water hydrated copper sulfate CuSO H 2 O CuSO 4.5H 2 O The student measured the temperature before and after the reaction. (i) The measurements showed that this reaction can be used for a hand warmer. Draw a ring around the correct answer to complete the sentence. When water is added to anhydrous copper sulfate the temperature increases. of the mixture decreases. stays the same. Anhydrous copper sulfate is white. What colour is seen after water is added to the anhydrous copper sulfate?... (iii) What does the symbol mean?... Page 14 of 26

15 (iv) The student heated a tube containing hydrated copper sulfate. Name the solid substance produced.... (Total 8 marks) Q9. Magnesium reacts with chlorine to make the ionic compound called magnesium chloride. (a) Complete the diagram by adding the electronic structures of the magnesium atom and the chloride ion. (b) Magnesium metal can be extracted from sea water. Sea water contains magnesium chloride, MgCl 2 (i) Calcium hydroxide, Ca(OH) 2, is added to the sea water. Magnesium hydroxide, Mg(OH) 2, is produced. MgCl 2 (aq) + Ca(OH) 2 (aq) Mg(OH) 2 (s) + CaCl 2 (aq) Name a method that could be used to separate magnesium hydroxide from the solution. An acid is then added to the magnesium hydroxide to make magnesium chloride. Name this acid.... Page 15 of 26

16 (c) Electrolysis is used to extract magnesium metal from magnesium chloride. (i) Why must the magnesium chloride be molten? The equation shows the reaction that takes place at the positive electrode. 2Cl Cl 2 + 2e Why is this reaction an oxidation reaction? (iii) Complete the equation for the reaction at the negative electrode. Mg 2+ Mg (Total 7 marks) Page 16 of 26

17 Q10. (a) (i) The diagram shows three vehicles travelling along a straight road at 14 m/s. Which vehicle has the greatest momentum?... Give the reason for your answer. Use the equation in the box to calculate the momentum of the motorbike when it travels at 14 m/s. momentum = mass velocity Show clearly how you work out your answer. Momentum =...kg m/s (b) The motorbike follows the lorry for a short time, and then accelerates to overtake both the lorry and van. (i) Complete the following sentence by drawing a ring around the correct line in the box. When the motorbike starts to overtake, the kinetic energy decreases. of the motorbike stays the same. increases. Page 17 of 26

18 Give a reason for your answer to part (b)(i). (iii) The graph shows the velocity of the motorbike up to the time when it starts to accelerate. The motorbike accelerates constantly, going from a speed of 14 m/s to a speed of 20 m/s in a time of 2 seconds. The motorbike then stays at 20 m/s. Complete the graph to show the motion of the motorbike over the next 4 seconds. (3) (Total 9 marks) Page 18 of 26

19 Q11. (a) A student set up the circuit shown in the diagram. The student uses the circuit to obtain the data needed to plot a current - potential difference graph for a diode. (i) Draw, in the boxes, the circuit symbol for a diode and the circuit symbol for a variable resistor. Diode Variable resistor The student made two mistakes when setting up the circuit. What two mistakes did the student make? Page 19 of 26

20 (b) After correcting the circuit, the student obtained a set of data and plotted the graph below. Potential difference in volts (i) At what potential difference did the diode start to conduct an electric current?... V Use data from the graph to calculate the resistance of the diode when the potential difference across the diode is 0.3 V. Use the correct equation from the Physics Equations Sheet. Resistance =... ohms (3) Page 20 of 26

21 (c) The diagram shows the trace produced by an alternating current (a.c.) supply on an oscilloscope. Each horizontal division on the oscilloscope screen represents a time of 0.01s. (i) Calculate the frequency of the a.c. supply. Frequency =... hertz A diode is now connected in series with the a.c. power supply. Why does the diode cause the trace on the oscilloscope screen to change? (Total 12 marks) Page 21 of 26

22 Q12. The diagram shows the structure of a cable. The cable is part of an undersoil heating circuit inside a large greenhouse. (a) The cable is connected to the mains electricity supply through a residual current circuit breaker (RCCB). If the cable is accidentally cut the RCCB automatically switches the circuit off. (i) What is the frequency of the mains electricity supply in the UK? What happens, as the cable is cut, to cause the RCCB to switch the circuit off? (iii) A circuit can also be switched off by the action of a fuse. Give one advantage of using a RCCB to switch off a circuit rather than a fuse. (b) The 230 volt mains electricity supply causes a current of 11 amps to flow through the cable. (i) Calculate the amount of charge that flows through the cable when the cable is switched on for 2 hours and give the unit. Use the correct equation from the Physics Equations Sheet. Charge =... (3) Page 22 of 26

23 Calculate the energy transferred from the cable to the soil in 2 hours. Use the correct equation from the Physics Equations Sheet. Energy transferred =... J (c) The heating circuit includes a thermistor. The thermistor is buried in the soil and acts as a thermostat to control the increase in the temperature of the soil. Describe how an increase in the temperature of the soil affects the thermistor (Total 11 marks) Q13. (a) The names of three types of radiation are given in List A. Some properties of these three types of radiation are given in List B. Draw one line from each type of radiation in List A to its correct property in List B. List A Type of radiation alpha beta gamma List B Property of radiation will pass through paper but is stopped by thin metal has the shortest range in air will not harm human cells is very weakly ionising (3) Page 23 of 26

24 (b) The radioactive isotope iodine-123 can be used by a doctor to examine the thyroid gland of a patient. The iodine, taken as a tablet, is absorbed by the thyroid gland. The gamma radiation emitted as the iodine atoms decay is detected outside the body. The doctor uses an isotope emitting gamma radiation to examine the thyroid gland rather than an isotope emitting alpha or beta radiation. Which one of the following gives a reason why gamma radiation is used? Tick ( ) one box. Gamma radiation will pass through the body. Gamma radiation is not deflected by a magnet. Gamma radiation has a long range in air. (c) Iodine-123 has a half-life of 13 hours. Use a word from the box to complete the sentence. all half most After 13 hours... of the iodine-123 atoms the thyroid absorbed have decayed. Page 24 of 26

25 (d) Iodine-123 and iodine-131 are two of the isotopes of iodine. Draw a ring around the correct answer to complete the sentence. electrons The nucleus of an iodine-123 atom has the same number of neutrons as the protons nucleus of an iodine-131 atom. (Total 6 marks) Page 25 of 26

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