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User: 25631 Logic gatesINTRODUCTION Logic gates are electronic components used in registers, memory chips and pro cessors to evaluate Boolean expressions . Therefore, before you read  this chapter, you must understand the basic Boolean expressions described in the previous chapter. This is because there is a one-to-one relationship between Boolean expressions and logic gates. Logic gates are represented as logic diagrams and also have a corresponding truth table. Consequently there is a logic diagram for each of the main Boolean expressions that we have looked at in the previous chapter. LEARNING OBJECTIVES In this chapter you will learn: •that there is a one-to-one relationship between logic gates andBoolean expressions •how logic gates are combined to build circuits within processors•how logic gates are used to evaluate Boolean expressions to producea result •how logic gates can be combined to create full systems •what full and half adders are.
 A-level students will learn: •what an edge-triggered D-type ﬂ  ip-ﬂ op  is.SPECIFICATION COVERAGE 3.6.4 Logic gates3.6.5 Boolean algebra KEYWORDSLogic gate: an electronic component used to perform Boolean algorithms.
 Boolean expressions: an equation  made up of Boolean operations.257The logic gates for each of the six basic Boolean expressions are shown in Figure 31.1.
 Gate Symbol OperatorA+B AAsB AsB A+Bandornot nandnor xor A + B Figure 31.1 Logic gate symbols and corresponding Boolean expressionsLogic gates take inputs and produce a single output. In the electronic circuit, the inputs are voltages with a high voltage representing a 1 and a low voltage representing a 0. For example, the logic gate for an AND expression is shown below: A B 2-input AND GateQFigure 31.2 The AND gateA and B are the inputs and Q is the output so this diagram is the equivalent of A.B = Q The standard ANSI/IEEE standard 91-1984 diagram for each logic gate is shown below along with its truth table and Boolean notation for ease of reference.
 SymbolBoolean expression Q = A.B A AND B = QTruth tableA     B          Q 0     0          00     1           01     0          01     1          1 AB 2-input AND GateQ Figure 31.3 The AND gate with truth tableKEYWORDAND gate: result is true if both inputsare true.31 LOGIC GATES258  31 Logic gatesSymbolBoolean expression Q = A+B A OR B = QTruth tableA     B          Q 0     0          00     1           11     0          11     1          1 AB 2-input OR GateQ Figure 31.4 The OR gate with truth tableSymbol Boolean expression Q = NOT A or A The inversion of A = QTruth tableA Q0 1 1 0A Inverter or NOT GateQFigure 31.5 The NOT gate with truth table SymbolBoolean expression Q = A.B A AND B = NOT QTruth tableA     B          Q0     0          10     1           11     0          11     1          0 AB 2-input NAND GateQ Figure 31.6 The NAND gate with truth tableSymbol Boolean expression Q = A+B A OR B = NOT QTruth tableA     B          Q0     0          10     1           01     0          01     1          0A B 2-input NOR GateQFigure 31.7 The NOR gate with truth tableKEYWORD NAND gate: result is true if any of the inputs are false.KEYWORD OR gate: result is true if either  input is true.
 KEYWORDNOT gate: inverts the result so true becomes false and false becomes true.
 KEYWORDNOR gate: result is true if both inputsare false.COMBINING LOGIC GATES 259SymbolBoolean expression Q = A + BTruth tableA     B          Q 0     0          00     1           11     0          11     1          0 AB 2-input Ex-OR GateQ Figure 31.8 The XOR gate with truth table●Combining logic gates Logic circuits are made up of a series of logic gates to create full systems.
 These can get very complex as there may be thousands of gates connected together. The output from the first gate becomes the input for the secondgate and so on. Therefore there will be various values generated until a finalvalue of Q is arrived at.
 For example, Figure 31.9 shows a simple alarm system where A and B areinputs from sensors and C is the manual override to turn the alarm off.O A or B = 1 means that the sensors have picked up an intruder. O A or B = 0 means that the sensors have not picked up an intruder.
 O C = 1 means that the override button has been pressed to turn the alarm off.O C = 0 means that the alarm will continue to sound.
 Therefore the only scenario where the alarm would sound is if either A ORB = 1 AND C = 0, which could be written as (A+B).C This could be shown as Q = (A+B).C and represented in the logic diagramin Figure 31.9 with the corresponding truth table.
 A+B AB C(A+B) sCC InputsA           B           C        Q 0           0           0        00           0           1        0 0           1   0        10           1           1        0 1           0           0        11           0           1        0 1           1           0        11           1                   1        0Outputs Figure 31.9 A logic circuit with truth tableKEYWORD Logic circuit: a combination of logic gates.KEYWORD XOR gate: result is true if either input is true but not if both  inputs are true.26031 Logic gatesTo follow this through: O Inputs from A and B pass through an OR gate. O Input C passes through a NOT gate. O These two results are passed through an AND gate to create the final result.In the example above a logic circuit has been constructed from the Boolean expression. It is also possible to construct a Boolean expression from a logic circuit. For example: C+DABC D(AsB)s(C+D)AsBAs the logic circuits get more complex, so the corresponding Boolean expression will get more complex: A B CAsBA+(AsB)+CA+(AsB)A●Full and half adderTo add together binary numbers, electronic circuits called adders are used.These are formed by combining logic gates together. Adders are commonlyfound in the Arithmetic Logic Unit (ALU)  in the CPU. There are two main t ypes, the half adder  and the full adder . To understand thisecti on, you need to make sure you have read Chapter 24 on adding binarynumbers together. Adders take in two bits A and B and add them to create a sum, S. So A + B = S.
 There is a further bit required called a carry bit , for when the result of the sumrequires a further digit. For example, binary addition of 1 + 1 results in 10 (i.e. 0 carry 1), so the carry bit is needed to store this additional bit.A half adder calculates the sum and stores the value of the carry bit C as well as the result S. The logic diagram to represent this is shown in Figure 31.10.
 AS CB Figure 31.10 A logic circuit for a half adderKEYWORDSArithmetic Logic Unit (ALU): partof the processor that processes and manipulates data.
 Half adder: a circuit that perf orms addition using inputs from A and B only.Full adder: a circuit that perf orms addition using inputs from A and B plus a carry bit.Carry bit: used to store a 0 or 1 dependin g on the result of binary addition.FULL AND HALF ADDER 261The XOR gate is used to look at inputs A and B: O If A = 0 and B = 1 or if A = 1 and B = 0 then the value for S will be 1. O Where A and B are both 0, the sum will be 0. O Where A and B are both 1, then the answer is 10 in binary, which means  that 0 is the result for S with the 1 put into the carry bit.
 The truth table shows the values of C and S for every possible input of A and B.
 Inputs OutputsABCS 0000100101011110 Half adders can be added/chained together to create a full adder. Full adders take three inputs, which are the two binary digits to be added, plus the carry bit from the previous addition. The output is the sum (S) plus the carry bit. Notice in the logic diagram below that Cin represents the value of the carry bit at the start of the addition and C out is the value of the carry bit at the end. C out from the first addition becomes C in on the second addition and so on.A Cin CoutB SFigure 31.11 A logic circuit for a full adderO The XOR gate works in the same way as a half adder to identify where the values of A and B are different. Where they are different the result is 1; where they are the same the result is 0.O A second XOR gate is used to perform the same function on the result of A and B with the value of C in to generate S. O A and B are ANDed together. O Cin is ANDed with the result A XOR B.
 O These two are ORed together to calculate C out.
 The truth table shows the values of C in and C out and S for every possible input of A and B. Inputs OutputsAB C in Cout S 00 0 0 010 0 0 1 010 0 1 11 0 1 00 1 0 110 1 1 001 1 1 011 1 1 1262 31 Logic gates●Edge-triggered D-type flip-flop Logic gates and logic circuits show how 0s and 1s can be manipulated to evaluate Boolean expressions. Data is passed around these gates and circuits at very high speed. However, as soon as the next set of inputs are fed in, the previous inputs are lost. As we have seen, often the next set of inputs come from the outputs of the previous calculation. Therefore some form of memory is needed and this is provided by a flip-flop , which is capable of storing one bit. Logic circuitMemory unitPrimary outputsSecondary outputsPrimaryinputs Secondaryinputs Figure 31.12 An edge-triggered D-type ﬂip-ﬂopThis means that the logic circuit is now receiving two sets of inputs, primary and secondary. It uses the system clock  to synchronise these requests. Each pulse of the system clock has a rising edge and a falling edge, which represents each pulse of the clock. Figure 31.13 How the ‘edge’ triggers a change of stateA level onlyKEYWORDS Flip-flop: a memory unit that can st ore one bit.
 Edge-triggered D-type flip-flop: a memory unit that changes state with each pulse of the clock.
 Clock: a device that generates a signal used to synchronise the components of a computer. Clock periodClock width Rising edgeFalling edgeIn the case of an edge-triggered D-type flip-flop this means that on each pulse of the clock, the flip-flop will change state. This means that for each pulse of the clock, data coming from the input will be stored in the flip-flop and continue to be output until the next trigger pulse is received.
 Practice questions can be found at the end of the section on page 264.
 EDGE-TRIGGERED D-TYPE FLIP-FLOP 263STUDY / RESEARCH TASKS1 Create a full speciﬁcation for an embedded system, e.g. operation of a  lift or an alarm system, implemented in the form of logic diagrams.2 Research SR, T and JK ﬂip-ﬂops. Find out how they work. 3 Explore how NAND gates can be used to create memory chips.KEY POINTS •Logic gates are a way of designing and describing the way in which electroniccomponents within registersand processor are constructed.
 •Logic gates evaluate Booleanexpresions. •There are six main symbolsthat relate directly to the six main Boolean expressions.
 •Logic gates can be combinedto represent more complex systems.
 •Logic gates effectivelyshow 0s and 1s are manipulated and binaryaddition takes place withinthem using either a half or fulladder.
 •An edge-triggered D-typeﬂip-ﬂop is a memory unit that temporarily stores the resultof an operation.TASKS1 What is the relationship between Boolean algebra and logic gates?2 What is a logic circuit? 3 Draw the logic diagram and truth table for each of the six main logic  gates: a)ANDb)OR c)NOTd)NOR e)NANDf)XOR4 Draw a logic diagram for the following Boolean expressions. a)(A+B)+(C.D) b)(A+B).Cc)(A.B).C.D5 Write the Boolean expression to build this circuit: AB CQD 6 Draw a logic diagram and truth table for a half adder.
 7 Draw a logic diagram using only NAND operations for A + B.
 8 What is the purpose of a ﬂip-ﬂop and what is the speciﬁc purpose of  the edge-triggered D-type ﬂip-ﬂop?
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3.6.5 Boolean algebra
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Be familiar with the use of Boolean identities and De Morgan’s laws to manipulate and simplify Boolean expressions.

3.6.4 Logic gates
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Construct truth tables for the following logic gates:
NOT
AND
OR
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Students should know and be able to use ANSI/IEEE standard 91-1984 Distinctive shape logic gate symbols for these logic gates.
Be familiar with drawing and interpreting logic gate circuit diagrams involving one or more of the above gates.
Complete a truth table for a given logic gate circuit.
Write a Boolean expression for a given logic gate circuit.
Draw an equivalent logic gate circuit for a given Boolean expression.
Recognise and trace the logic of the circuits of a half-adder and a full-adder.
Construct the circuit for a half-adder.
Be familiar with the use of the edge-triggered D-type flip-flop as a memory unit.
Knowledge of internal operation of this flip-flop is not required.


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User: These are the content of said exam questions, these are the ONLY exam questions, you will use these later, delivered in form 'fil', JSON: {'Q23S207P3': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Using the rules of Boolean algebra, simplify the following expression.</p>\r\n<p class="graph"><img src="AA_COM/Q23S207P3_files_Q/img01.jpg"/></p>\r\n<p class="indent1new">You <b>must</b> show your working.</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="mark">(Total 4 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><b>Marks are for AO2 (application)</b></p>\r\n<p class="indent1new"><b>Marking guidance for examiners</b></p>\r\n<p class="indent1 m-t-0">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Award marks for working out until an incorrect step has been made.</p>\r\n<p class="indent1 m-t-0">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;If, in any one step, a candidate is simplifying different parts of an expression simultaneously award all relevant marks for this multiple stage but don&#x2019;t award any further marks for working in any parts simplified incorrectly. Example, if the expression P.P.(P+Q) + P.P.1 was changed to P.(P+Q)+P.0, the candidate would get one mark for simplifying the first part to P.(P+Q) and could get further marks for correctly simplifying this part of the expression further but should not be awarded marks for simplifying the incorrectly changed part P.0 (i.e. to 0).</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new"><b>Mark as follows:</b></p>\r\n<p class="indent1new"><b>MAX 3 marks for</b> working</p>\r\n<p class="indent1new">Award one mark each for applying the techniques below:</p>\r\n<p class="indent1 m-t-0">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A successful application of De Morgan&#x2019;s Law (and any associated cancellation of NOTs) that produces a simpler expression.</p>\r\n<p class="indent1 m-t-0">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Successfully expanding brackets.</p>\r\n<p class="indent1 m-t-0">&#149;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Extracting common factors from terms.</p>\r\n<p class="indent1new">Award one mark for each application of a Boolean identity <b>MAX 2</b>.</p>\r\n<p class="indent1new"><b>Note:</b> A simpler expression is one that is logically equivalent to the original expression but uses fewer logical operators.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new"><b>1 mark</b> for final answer: B</p>\r\n<p class="indent2new"><img src="AA_COM/M23S207P3_files_M/img01.jpg"/>&nbsp;</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new"><b>Alternative answer 1</b></p>\r\n<p class="indent2new"><img src="AA_COM/M23S207P3_files_M/img02.jpg"/>&nbsp;</p>\r\n<p class="mark">[4]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Simplifying Boolean expressions has been assessed on previous papers and almost half the students scored full marks. A lot of students were able to gain a few marks before making a mistake in precedence when simplifying the step <img class="vert-middle vert-up-1" src="AA_COM/E23S207P3_files_E/img01.jpg"/> incorrectly taking the B+B to B.</p></h5>', 'notes': '', 'resources': ''}, 'QS18S29P04': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Using the rules of Boolean algebra, simplify the following expression.</p>\r\n<p class="graph"><img src="AA_COM/QS18S29P04_files_Q/img01.jpg"/>&nbsp;</p>\r\n<p class="indent1new">You <b>must</b> show your working.</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="rightnew answer-toggle">Answer _________________________________________</p>\r\n<p class="mark">(Total 4 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question indentright"><b>Marks are for AO2 (apply)</b></p>\r\n<p class="indent1new indentright"><b>Marking guidance for examiners</b></p>\r\n<p class="indent1 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;Award marks for working out until an incorrect step has been made.</p>\r\n<p class="indent1 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;If, in any one step, a candidate is simplifying different parts of an expression simultaneously award all relevant marks for this multiple stage but don’t award any further marks for working in any parts simplified incorrectly. Example, if the expression P.P.(P+Q) + P.P.1 was changed to P.(P+Q)+P.0, the candidate would get one mark for simplifying the first part to P.(P+Q) and could get further marks for correctly simplifying this part of the expression further but should not be awarded marks for simplifying the incorrectly changed part P.0 (ie to 0)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Mark as follows</b></p>\r\n<p class="indent1new indentright"><b>MAX 3 marks for working</b></p>\r\n<p class="indent1new indentright">Award one mark each for applying the techniques below:</p>\r\n<p class="indent1 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;a successful application of De Morgan’s Law (and any associated cancellation of NOTs) that produces a simpler expression</p>\r\n<p class="indent1 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;successfully expanding brackets</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright">Award one mark for each application of a Boolean identity <b>MAX 2</b>.</p>\r\n<p class="indent1new indentright"><b>Note:</b> A simpler expression is one that is logically equivalent to the original expression but uses fewer logical operators.</p>\r\n<p class="indent1new indentright"><b>Example working (1)</b></p>\r\n<p class="indent1new"><img src="AA_COM/MS18S29P04_files_M/img01.jpg"/>&nbsp;</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example working (2)</b></p>\r\n<p class="indent1new"><img src="AA_COM/MS18S29P04_files_M/img02.jpg"/>&nbsp;</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example working (3)</b></p>\r\n<p class="indent1new"><img src="AA_COM/MS18S29P04_files_M/img03.jpg"/>&nbsp;</p>\r\n<p class="indent1new indentright"><b>1 mark</b> for final answer A XOR B // A Exclusive OR B // A EOR B // A EXOR B // A &#10753; B</p>\r\n<p class="mark">[4]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Most commonly students did not know the identity between A&#773; &#8901; B + B&#773; &#8901; A and A &#10753; B. Prior to this stage of the calculation, the most common error was students misapplying De Morgan’s Law. This led to an incorrect algebraic statement which led to students being unable to access later mark points.</p></h5>', 'notes': '', 'resources': ''}, 'Q22S207P5': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Using the rules and identities of Boolean algebra, simplify the following Boolean expression.</p>\r\n<p class="graph"><img src="AA_COM/Q22S207P5_files_Q/img01.jpg"/>&nbsp;</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">Answer ________________________________________________________________</p>\r\n<p class="mark">(Total 4 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><b>Marks are for AO2 (application)</b></p>\r\n<p class="indent1new indentright"><b>Marking guidance for examiners</b></p>\r\n<p class="indent1">&#8226;&emsp;&emsp;&nbsp;Award marks for working out until an incorrect step has been made.</p>\r\n<p class="indent1 m-t-0">&#8226;&emsp;&emsp;&nbsp;If, in any one step, a candidate is simplifying different parts of an expression simultaneously award all relevant marks for this multiple stage but don&#x2019;t award any further marks for working in any parts simplified incorrectly. For example, if the expression P.P.(P+Q) + P.P.1 was changed to P.(P+Q)+P.0, the candidate would get one mark for simplifying the first part to P.(P+Q) and could get further marks for correctly simplifying this part of the expression further but should not be awarded marks for simplifying the incorrectly changed part P.0 (ie to 0).</p>\r\n<p class="indent1new indentright"><b>1 mark</b> for final answer of <img class="vert-middle vert-up-1" src="AA_COM/M22S207P5_files_M/img01.jpg"/>;</p>\r\n<p class="indent1new indentright"><b>3 marks</b> for working</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>MAX 3</b> for working. Award up to two marks for applying each of the three techniques (one mark per application) to produce a simpler expression.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1">&#8226;&emsp;&emsp;&nbsp;Applying De Morgan&#x2019;s Theorem.</p>\r\n<p class="indent1">&#8226;&emsp;&emsp;&nbsp;Multiply and/or factorise brackets.</p>\r\n<p class="indent1">&#8226;&emsp;&emsp;&nbsp;Using a law or identity.</p>\r\n<p class="indent1new indentright"><b>Note:</b> A simpler expression is one that is logically equivalent to the original expression but uses fewer logical operators.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example 1:</b></p>\r\n<p class="indent1new"><img src="AA_COM/M22S207P5_files_M/img02.jpg"/>&nbsp;</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example 2:</b></p>\r\n<p class="indent1new"><img src="AA_COM/M22S207P5_files_M/img03.jpg"/>&nbsp;</p>\r\n<p class="mark">[4]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Simplifying Boolean expressions has been assessed on previous papers and this was a relatively simple simplification. However, less than a third of students got full marks, with many of those who did not multiplying out the brackets incorrectly. In this question one half of the expression was an AND and the other was an OR. When multiplying out the brackets many students incorrectly placed an OR between all parts, eg <i>A &#x00B7; A</i> + <i>A</i> &#x00B7; <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/> + <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/> &#x00B7; <i>A</i> + <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/> + <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/> instead of <i>A &#x00B7; A</i> &#x00B7; <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/> + <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/> &#x00B7; <i>A</i> &#x00B7; <img class="vert-middle" src="AA_COM/E22S207P5_files_E/img01.jpg"/>. Students need to have practiced on a large variety of expressions.</p></h5>', 'notes': '', 'resources': ''}, 'QW11203': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Write the following Boolean expressions in their simplest forms.</span></p>\r<table class=MsoTableGrid cellspacing=0 cellpadding=4 style=\'margin-left:20.0pt;border-collapse:collapse;border:0\'> \r\t<tr>  \r\t\t<td width=30><p class=boxl>(a)</p></td>\r\t\t<td width=70><p class=boxl>&nbsp;<img src="AA_COM/QW11203_files_Q/img01.png"></p></td>\r\t</tr>\r</table>\r<p class="indent2new m-t-0 answer-toggle">___________________________________________________________________</p>\r<p class="mark">(1)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><table class=MsoTableGrid cellspacing=0 cellpadding=4 style=\'margin-left:20.0pt;border-collapse:collapse;border:0\'> \r\t<tr>  \r\t\t<td width=30><p class=boxl>(b)</p></td>\r\t\t<td width=100><p class=boxl>&nbsp;<img src="AA_COM/QW11203_files_Q/img02.png"></p></td>\r\t</tr>\r</table>\r<p class="indent2new m-t-0 answer-toggle">___________________________________________________________________</p>\r<p class="mark">(1)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><table class=MsoTableGrid cellspacing=0 cellpadding=4 style=\'margin-left:20.0pt;border-collapse:collapse;border:0\'> \r\t<tr>  \r\t\t<td width=30><p class=boxl>(c)</p></td>\r\t\t<td width=110><p class=boxl>&nbsp;<img src="AA_COM/QW11203_files_Q/img03.png"></p></td>\r\t</tr>\r</table>\r<p class="indent2new m-t-0 answer-toggle">___________________________________________________________________</p>\r<p class="mark">(1)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1">(d)&nbsp;&nbsp;&nbsp;&nbsp;A . (B+1)</p>\r<p class="indent2new answer-toggle">___________________________________________________________________</p>\r<p class="mark">(1)</p> \r<p class="mark">(Total 4 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><span style=\'position:relative;top:3pt\'><img src="AA_COM/MW11203_files_M/ab.png"></span> becomes A + B ;<br/><b>A</b> (A&#x002B;B);<br/><b>A</b> A OR B;</span></p>\r<p class="indent1new indentright m-t-0">B&#x002B; B.<span style=\'position:relative;top:1pt\'><img src="AA_COM/MW11203_files_M/c.png"> becomes B ;</span></p>\r<p class="indent1new indentright m-t-0"><b>A</b> B&#x002B; A. <span style=\'position:relative;top:1pt\'><img src="AA_COM/MW11203_files_M/b.png"> becomes A ;</span></p>\r<p class="indent1new indentright m-t-0"><b>A</b> (B&#x002B;1) becomes A ;</p>\r<p class="indent1new indentright"><i>1 mark for each</i></p>\r<p class="mark">[4]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">This question focused on simplifying four short Boolean expressions, in contrast to earlier papers which required the simplification of more complex expressions. Candidates scored well on part (a) and it is clear that De Morgan&#x2019;s laws are now well known. Part (c) caused fewer problems than parts (b) and (d). It does appear that candidates need more exposure to simplifying expressions. A few candidates inserted new letters into their answers for no apparent reason. Quite a few candidates gave no response.</span></p></h5>', 'notes': '', 'resources': ''}, 'QS17L24C': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Using the rules of Boolean algebra, simplify the following Boolean expression.</p>\r\n<p class="graph"><img src="AA_COM/QS17L24C_files_Q/img01.jpg"/>&nbsp;</p>\r\n<p class="indent1new">You <b>must</b> show your working.</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="rightnew answer-toggle">Answer _________________________________________</p>\r\n<p class="mark">(Total 4 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question indentright"><b>All marks AO2 (apply)</b></p>\r\n<p class="indent1new indentright"><b>Marking guidance for examiners</b></p>\r\n<p class="indent1 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;Award marks for working out until an incorrect step has been made.</p>\r\n<p class="indent1 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;If, in any one step, a candidate is simplifying different parts of an expression simultaneously award all relevant marks for this multiple stage but don’t award any further marks for working in any parts simplified incorrectly. For example, if the expression P&thinsp;.P&thinsp;.(P + Q) + P&thinsp;.P&thinsp;.1 was changed to P&thinsp;.(P + Q) + P&thinsp;.0, the candidate would get one mark for simplifying the first part to P&thinsp;.(P + Q) and could get further marks for correctly simplifying this part of the expression further but should not be awarded marks for simplifying the incorrectly changed part P&thinsp;.0 (ie to 0)</p>\r\n<p class="indent1new indentright"><b>1 mark:</b> for final answer: B + C</p>\r\n<p class="indent1new indentright"><b>MAX 3</b> for working. Award up to two marks for applying each one of the three techniques (one mark per application):</p>\r\n<p class="indent2 indentright">&#8226;&emsp;&emsp;&nbsp;a successful application of De Morgan’s Law (and any associated cancellation of NOTs) that produces a simpler expression.</p>\r\n<p class="indent2 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;applying an identity other than cancelling NOTs that produces a simpler expression.</p>\r\n<p class="indent2 indentright m-t-0">&#8226;&emsp;&emsp;&nbsp;successfully expanding brackets.</p>\r\n<p class="indent1new indentright"><b>Note:</b> A simpler expression is one that is logically equivalent to the original expression but uses fewer logical operators.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example Working (1)</b></p>\r\n<p class="indent1new"><img class="vert-middle" src="AA_COM/MS17L24C_files_M/img02.jpg"/>&nbsp;</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example Working (2)</b></p>\r\n<p class="indent1new"><img class="vert-middle" src="AA_COM/MS17L24C_files_M/img03.jpg"/>&nbsp;</p>\r\n<p class="mark">[4]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Most students achieved some marks for this question part but only a fifth achieved full marks. The most commonly made mistake was to incorrectly apply the identity A+A&#773;=1 to the subexpression A&#773;+A∙(A+B) which failed to recognise that this could not be done because of the order of precedence of AND (.) and OR (+). Another mistake made by some students was to cancel NOTs when they could not be cancelled, for example believing that the NOTs in (B&#773;∙C&#773;) could be cancelled with the longer NOT that related to the entire expression.</p></h5>', 'notes': '', 'resources': ''}, 'QS19S26P03': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">De Morgan’s laws can be applied to enable a combination of logic gates to be replaced by a single gate that produces the same output.</p>\r\n<p class="indent1new">What single gate could replace the combination of gates in the expression <img class="vert-middle vert-up-1" src="AA_COM/QS19S26P03_files_Q/img01.jpg"/>?</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="mark">(Total 1 mark)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><b>Mark is for AO1 (understanding)</b></p>\r\n<p class="indent1new">OR;</p>\r\n<p class="indent1new m-t-0"><b>A.</b> A+B // +</p>\r\n<p class="mark">[1]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Many students achieved this mark. Where the mark was not achieved, the most common incorrect answer was an AND gate which shows a lack of understanding of De Morgan’s Laws.</p></h5>', 'notes': '', 'resources': ''}, 'QS18L210': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Using the laws of Boolean algebra, show that:</p>\r\n<p class="graph"><img src="AA_COM/QS18L210_files_Q/img01.jpg"/>&nbsp;</p>\r\n<p class="indent1new">You <b>must</b> show your working.</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="indent1new answer-toggle">_______________________________________________________________________</p>\r\n<p class="mark">(Total 4 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question indentright">All marks AO2 (apply)</p>\r\n<p class="indent1new indentright">Award up to four marks for the working shown, but <b>Max 3</b> if the response does not show that (A + B) ∙ (B + C ∙ (D + D&#773;)) = A ∙ C + B</p>\r\n<p class="indent1new indentright"><b>1 mark</b> for each application of an identity or theorem that produces an expression that is logically equivalent to the original expression but uses fewer logical operators.</p>\r\n<p class="indent1new indentright m-t-0"><b>1 mark</b> for a successful application of the distribution law – only one mark, regardless of how many times this has been applied</p>\r\n\r\n<p class="indent1new indentright">Continue marking until an incorrect step is encountered. If a student misses out some steps but does not make an error then continue marking.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example Solution 1</b></p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left1">\r\n\t<tr>\r\n\t\t<td class="col-10 vert-top no-border">\r\n\t\t\t<p class="padded text-left">(A + B) &#8901; (B + C &#8901; (D + D&#773;))</p>\r\n\t\t\t<p class="padded text-left m-t-0">= (A + B) &#8901; (B + C &#8901; 1)</p>\r\n\t\t\t<p class="padded text-left m-t-0">= (A + B) &#8901; (B + C)</p>\r\n\t\t\t<p class="padded text-left m-t-0">= A &#8901; B + A &#8901; C + B &#8901; B + B &#8901; C</p>\r\n\t\t\t<p class="padded text-left m-t-0">= A &#8901; B + A &#8901; C + B + B &#8901; C</p>\r\n\t\t\t<p class="padded text-left m-t-0">= A &#8901; B + A &#8901; C + B</p>\r\n\t\t\t<p class="padded text-left m-t-0">= A &#8901; C + B</p>\r\n\t\t</td>\r\n\t\t<td class="col-14 vert-top no-border">\r\n\t\t\t<p class="padded text-left">&nbsp;</p>\r\n\t\t\t<p class="padded text-left m-t-0">By identity X + X&#773; = 1</p>\r\n\t\t\t<p class="padded text-left m-t-0">By identity X &#8901; 1 = X</p>\r\n\t\t\t<p class="padded text-left m-t-0">Using distribution law</p>\r\n\t\t\t<p class="padded text-left m-t-0">By identity X &#8901; X = X</p>\r\n\t\t\t<p class="padded text-left m-t-0">By redundancy theorem X + X &#8901; Y = X</p>\r\n\t\t\t<p class="padded text-left m-t-0">By redundancy theorem X + X &#8901; Y = X</p>\r\n\t\t</td>\r\n\t</tr>\r\n</table></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Example Solution 2</b></p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left1">\r\n\t<tr>\r\n\t\t<td class="col-11 vert-top no-border">\r\n\t\t\t<p class="padded text-left">(A + B) &#8901; (B + C &#8901; (D + D&#773;))</p>\r\n\t\t\t<p class="padded text-left m-t-0">= (A + B) &#8901; (B + C &#8901; 1)</p>\r\n\t\t\t<p class="padded text-left m-t-0">= (A + B) &#8901; (B + C)</p>\r\n\t\t\t<p class="padded text-left m-t-0">= A &#8901; C + B</p>\r\n\t\t</td>\r\n\t\t<td class="col-15 vert-top no-border">\r\n\t\t\t<p class="padded text-left">&nbsp;</p>\r\n\t\t\t<p class="padded text-left m-t-0">By identity X + X&#773; = 1</p>\r\n\t\t\t<p class="padded text-left m-t-0">By identity X &#8901; 1 = X</p>\r\n\t\t\t<p class="padded text-left m-t-0">Using distribution law (<u>this jump is worth 2&nbsp;marks</u>)</p>\r\n\t\t</td>\r\n\t</tr>\r\n</table>\r\n<p class="mark">[4]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">This is the first time that students have been asked to produce a proof that two Boolean expressions are equivalent. It was well tackled, with over 40% of students achieving full marks. A common mistake was to believe that D + D&#773; = 0.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new">Some responses were difficult to mark as the way that students laid them out made it unclear what order they had done things in. It is particularly important when presenting a proof that the examiner can see what steps the student took and in what order these were made. In other responses, students would miss out steps, making jumps in their working that were not convincing enough to be a proof.</p></h5>', 'notes': '', 'resources': ''}, 'QS1726A': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="questiona">(a)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Complete the truth table below to show the output <b>Q</b> of an AND gate with two inputs <b>A</b> and <b>B</b>.</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left5">\r\n\t<tr>\r\n\t\t<td colspan="2" class="col-6"><p class="padded"><b>Inputs</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>Output</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>Q</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n</table>\r\n<p class="mark">(1)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1">(b)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;State the name of the logic gate that is represented by the truth table below.</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left5">\r\n\t<tr>\r\n\t\t<td colspan="2" class="col-6"><p class="padded"><b>Inputs</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>Output</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>Q</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t</tr>\r\n</table>\r\n<p class="indent2new answer-toggle">___________________________________________________________________</p>\r\n<p class="mark">(1)</p>\r\n<p class="mark">(Total 2 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="questiona indentright">(a)&emsp;&nbsp;<b>1 mark</b> for table completed correctly</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left2">\r\n\t<tr>\r\n\t\t<td colspan="2" class="col-6 vert-top"><p class="padded"><b>Inputs</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>Output</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>Q</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>0</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>0</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>0</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>1</b></p></td>\r\n\t</tr>\r\n</table>\r\n<p class="levelms">1</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1 indentright">(b)&emsp;&nbsp;XOR / EOR / exclusive-or;</p>\r\n<p class="levelms">1</p>\r\n<p class="mark">[2]</p></h5>', 'examinerreport': '', 'notes': '', 'resources': ''}, 'QS19S26P01': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">State the name of the logic gate represented by the truth table shown in the table below.</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left4">\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>Q</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t</tr>\r\n</table></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new answer-toggle">Answer ________________________________________________________________</p>\r\n<p class="mark">(Total 1 mark)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><b>Mark is for AO1 (knowledge)</b></p>\r\n<p class="indent1new">NOR;</p>\r\n<p class="mark">[1]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">This question was generally well answered, although a number of students did not know the name of the gate.</p></h5>', 'notes': '', 'resources': ''}, 'Q22S207P3': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Draw the logic circuit for the following Boolean expression.</p>\r\n<p class="graph"><img src="AA_COM/Q22S207P3_files_Q/img01.jpg"/>&nbsp;</p>\r\n<p class="graph"><img src="AA_COM/Q22S207P3_files_Q/img02.jpg"/>&nbsp;</p>\r\n<p class="mark">(Total 2 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><b>Marks are for AO2 (application)</b></p>\r\n<p class="indent1new indentright"><b>1 mark</b> for each design point</p>\r\n<p class="indent1new indentright">A and B are connected to the inputs of an AND gate and the output of the AND gate connected to the input of a NOT gate // A and B connected to the inputs of a NAND gate;</p>\r\n<p class="indent1new indentright">The final two gates in the circuit are an OR gate followed by a NOT gate // The final gate in the circuit is a NOR gate;</p>\r\n<p class="indent1new indentright"><b>A.</b> award 2 marks if the candidate has correctly simplified the Boolean expression and drawn a fully correct logic circuit.</p>\r\n<p class="indent1new indentright"><b>MAX 1</b> if circuit does not correctly reflect the Boolean expression.</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Possible answers:</b></p>\r\n<p class="indent2new"><img src="AA_COM/M22S207P3_files_M/img01.jpg"/>&nbsp;</p>\r\n<p class="mark">[2]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Questions like this involving drawing logic circuits have been in previous exam papers and this was well answered with three-quarters of students scoring at least one mark and well over half getting both marks. Some students tried to simplify the Boolean expression before they drew the logic circuit which was not needed.</p></h5>', 'notes': '', 'resources': ''}, 'QW10207': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">The figure below shows a logic circuit.</p>\r<p class="graph"><img src="AA_COM/QW10207_files_Q/img01.png">&nbsp;</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1">(a) &nbsp;&nbsp;&nbsp;&nbsp;Complete the truth table below for the logic circuit shown in the above figure. Write the correct value of the output Q for each of the listed sets of inputs.</p>\r<p class="bottom">&nbsp;</p>\r<table class=MsoTableGrid cellspacing=0 cellpadding=4 style=\'margin-left:48.0pt;border-collapse:collapse\'> \r\t<tr>  \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box><b>Input <br/>A</b></p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box><b>Input <br/>B</b></p></td> \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box><b>Input <br/>C</b></p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box><b>Output <br/>Q</b></p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>1</p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>0</p></td> \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>1</p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>&nbsp;</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>0</p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>1</p></td> \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>0</p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>&nbsp;</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>0</p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>1</p></td> \r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>1</p></td>\r\t\t<td valign=top style=\'width:60.0pt;border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=box>&nbsp;</p></td> \r\t</tr> \r</table>\r<p class="mark">(3)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1">(b) &nbsp;&nbsp;&nbsp;&nbsp;Two of the gates in the circuit shown in the above figure could be replaced by a single gate.</p>\r<p class="indent2">(i)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Which <b>two</b> gates could be replaced&#x003F;</p>\r<p class="indent3new answer-toggle">______________________________________________________________</p>\r<p class="mark">(1)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent2">(ii)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;What single gate would be used instead&#x003F;</p>\r<p class="indent3new answer-toggle">______________________________________________________________</p>\r<p class="mark">(1)</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1">(c) &nbsp;&nbsp;&nbsp;&nbsp;Why is it an advantage to use as few gates as possible in a logic circuit&#x003F;</p>\r<p class="indent2new answer-toggle">___________________________________________________________________</p>\r<p class="indent2new answer-toggle">___________________________________________________________________</p>\r<p class="mark">(1)</p> \r<p class="mark">(Total 6 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">&nbsp;</p>\r<p class="indent1 indentright m-t-0">(a)&nbsp;&nbsp;&nbsp;&nbsp; </span>1; <b>A</b> True<br/>1; <b>A</b> True<br/>0; <b>A</b> False</p>\r<p class="levelms">3</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1a indentright" >(b)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;AND and NOT</p>\r<p class="levelms">1</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent2 indentright">(ii)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; NAND // NAND gate<br/><b>R</b> NOT AND</p>\r<p class="levelms">1</p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1 indentright">(c) &nbsp;&nbsp;&nbsp;&nbsp;Minimise cost of production;<br/>Reduce propagation delay//speed up processing;<br/>Minimise heat generated;<br/>Reduce power consumption;</p>\r<p class="indent2new indentright m-t-0"><b>NE</b> simpler to produce/makes circuit simpler<br/><b>NE</b> reduce number of gates in chip</p>\r<p class="levelms">1</p> \r<p class="mark">[6]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">The majority of candidates answered part (a) very well. It would seem that, given a logic gate diagram and a truth table made it quite easy for the candidates to answer when compared with Question 2 on Boolean algebra.</span></p>\r<p class="indent1new">Part (b) was also well answered. The gates that could be replaced were usually correctly stated, however AND and NOR and NOT and OR sometimes appeared incorrectly. It was obvious from the answers that most candidates could convert the AND gate followed by a NOT gate into a NAND gate.</p>\r<p class="indent1new">Part (c) was weakly answered even though there was a wide range of potential answers for a single mark. Where candidates went wrong was in giving answers about &#x201C;making it easier for humans to understand and / or interpret&#x201D;. Reducing the number of gates would reduce the propagation delay, thus speeding up processing. It could also reduce power consumption and the cost of manufacturing  the circuit.</p></h5>', 'notes': '', 'resources': ''}, 'QS18S29P02': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">The diagram below shows a logic gate symbol.</p>\r\n<p class="graph m-t-1"><img src="AA_COM/QS18S29P02_files_Q/img01.jpg"/>&nbsp;</p>\r\n<p class="indent1new">Complete the truth table below for the logic gate shown in the diagram above.</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table align4">\r\n\t<tr>\r\n\t\t<td class="col-4"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-4"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-4"><p class="padded"><b>Q</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4"><p class="padded">0</p></td>\r\n\t\t<td class="col-4"><p class="padded">0</p></td>\r\n\t\t<td class="col-4"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4"><p class="padded">0</p></td>\r\n\t\t<td class="col-4"><p class="padded">1</p></td>\r\n\t\t<td class="col-4"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4"><p class="padded">1</p></td>\r\n\t\t<td class="col-4"><p class="padded">0</p></td>\r\n\t\t<td class="col-4"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4"><p class="padded">1</p></td>\r\n\t\t<td class="col-4"><p class="padded">1</p></td>\r\n\t\t<td class="col-4"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n</table>\r\n<p class="mark">(Total 1 mark)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question indentright"><b>Mark is for AO1 (knowledge)</b></p>\r\n<p class="indent1new indentright"><b>1 mark</b> for correct column Q;</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left1">\r\n\t<tr>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>Q</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>1</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>1</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>1</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-4 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-4 vert-top"><p class="padded"><b>0</b></p></td>\r\n\t</tr>\r\n</table>\r\n<p class="mark">[1]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">The majority of students got the mark point on this question part by correctly completing the truth table for the NAND gate.</p></h5>', 'notes': '', 'resources': ''}, 'Q20S205P1': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Complete the truth table for A NAND B.</p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left3">\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-6"><p class="padded"><b>A NAND B</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">0</span></p></td>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">0</span></p></td>\r\n\t\t<td class="col-6"><p class="padded m-t-1 m-b-1">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">0</span></p></td>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">1</span></p></td>\r\n\t\t<td class="col-6"><p class="padded m-t-1 m-b-1">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">1</span></p></td>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">0</span></p></td>\r\n\t\t<td class="col-6"><p class="padded m-t-1 m-b-1">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">1</span></p></td>\r\n\t\t<td class="col-3"><p class="padded m-t-1 m-b-1"><span class="comp-top">1</span></p></td>\r\n\t\t<td class="col-6"><p class="padded m-t-1 m-b-1">&nbsp;</p></td>\r\n\t</tr>\r\n</table>\r\n<p class="mark">(Total 1 mark)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question"><b>Mark is for AO1 (knowledge)</b></p>\r\n<p class="indent2new indentright"><img class="vert-middle" src="AA_COM/M20S205P1_files_M/img01.jpg"/></p>\r\n<p class="mark">[1]</p></h5>', 'examinerreport': '', 'notes': '', 'resources': ''}, 'QW11202': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">The diagram below shows a logic circuit.</span></p>\r<p class="indent1new"><img align="middle;" src="AA_COM/QW11202_files_Q/img01.png">&nbsp;</p>\r<p class="indent1new">Complete the truth table for the inputs that have been given.</p>\r<p class="bottom">&nbsp;</p>  \r<table class=MsoTableGrid border=0 cellspacing=0 cellpadding=4  style=\'margin-left:30pt;border-collapse:collapse\'>  \r\t<tr>     \r\t\t<td colspan=6 valign=top style=\'border:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>Inputs</b></p></td>   \r\t\t<td width=55 valign=top style=\'border:none;border-bottom:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border:none;border-bottom:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border:none;border-bottom:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>  \r\t</tr>  \r\t<tr>       \r\t\t<td width=55 valign=top style=\'border:solid windowtext 1.0pt;border-top:none;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>A</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>B</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>C</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>D</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>E</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>F</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>G</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>H</b></p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box><b>K</b></p></td>  \r\t</tr>  \r\t<tr>       \r\t\t<td width=55 valign=top style=\'border:solid windowtext 1.0pt;border-top:none;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>  \r\t</tr>  \r\t<tr>       \r\t\t<td width=55 valign=top style=\'border:solid windowtext 1.0pt;border-top:none;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>  \r\t</tr>  \r\t<tr>       \r\t\t<td width=55 valign=top style=\'border:solid windowtext 1.0pt;border-top:none;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>0</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>  \r\t</tr>  \r\t<tr>       \r\t\t<td width=55 valign=top style=\'border:solid windowtext 1.0pt;border-top:none;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>1</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>   \r\t\t<td width=55 valign=top style=\'border-top:none;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0cm 5.4pt 0cm 5.4pt\'><p class=box>&nbsp;</p></td>  \r\t</tr> \r</table>\r<p class="mark">(Total 3 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">&nbsp;</p>\r<table class=MsoTableGrid cellspacing=0 cellpadding=0 style=\'margin-top:-0.4cm;margin-left:25.0pt;border-collapse:collapse\'> \r\t<tr>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>G</p></td>\r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>H</p></td>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>K</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>0</p></td>\r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td>\r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>0</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td>\r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>0</p></td>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td>\r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>0</p></td>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>1</p></td> \r\t</tr> \r\t<tr>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>;</p></td>\r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>;</p></td>  \r\t\t<td valign=top style=\'width:50.0pt;border:none;padding:0cm 5.4pt 0cm 5.4pt;\'><p class=boxl>;</p></td> \r\t</tr> \r</table>\r<p class="indent1new indentright"><i>1 mark for each correct column</i></p>\r<p class="mark">[3]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">This question asked candidates to complete a truth table for a logic circuit with multiple gates. Many candidates gave fully correct answers. A few candidates misidentified the NAND gate as an AND gate.</span></p></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new">The majority of candidates secured the mark for G which was an OR gate. The combining of gates for the H and K answers caused problems for weaker candidates.</p></h5>', 'notes': '', 'resources': ''}, 'QS17S25B': {'question': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Complete the truth table below to prove that <b>A +</b> <img class="vert-middle vert-up-1" src="AA_COM/QS17S25B_files_Q/overlineb.jpg"/> is equivalent to <img src="AA_COM/QS17S25B_files_Q/img01.jpg"/></p></p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left1">\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">0</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">1</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3"><p class="padded">&nbsp;</p></td>\r\n\t</tr>\r\n</table>\r\n<p class="mark">(Total 3 marks)</p></h5>', 'markscheme': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question indentright"><b>Marks are for AO2 (apply)</b></p>\r\n<p class="bottom">&nbsp;</p>\r\n<table class="data-table left1">\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">&nbsp;</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded comp-top font12"><b>1</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded comp-top font12"><b>2</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded comp-top font12"><b>3</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded comp-top font12"><b>4</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded comp-top font12"><b>5</b></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>A</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>B</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><img class="vert-middle vert-up-1" src="AA_COM/MS17S25B_files_M/overlineb.jpg"/></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><b>A + </b><img class="vert-middle vert-up-1" src="AA_COM/MS17S25B_files_M/overlineb.jpg"/></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><img class="vert-middle vert-up-1" src="AA_COM/MS17S25B_files_M/overlinea.jpg"/></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><img class="vert-middle vert-up-1" src="AA_COM/MS17S25B_files_M/overlinea.jpg"/> &#8226; <b>B</b></p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded"><img class="vert-middle vert-up-1" src="AA_COM/MS17S25B_files_M/img01.jpg"/></p></td>\r\n\t</tr>\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t</tr>\r\n\t\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t</tr>\r\n\t\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t</tr>\r\n\t\r\n\t<tr>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">0</p></td>\r\n\t\t<td class="col-3 vert-top"><p class="padded">1</p></td>\r\n\t</tr>\r\n</table></h5><h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="indent1new indentright"><b>Mark as follows:</b></p>\r\n<p class="indent1new indentright m-t-0"><b>1 mark</b> for column 1 and 3 correct</p>\r\n<p class="indent1new indentright m-t-0"><b>1 mark</b> for column 4 correct</p>\r\n<p class="indent1new indentright m-t-0"><b>1 mark</b> for columns 2 and 5 correct and identical</p>\r\n<p class="indent1new indentright"><b>I</b>. order of columns</p>\r\n<p class="mark">[3]</p></h5>', 'examinerreport': '<h5 class=\'contentSeparator\' style=\'page-break-inside: avoid;\'><div class=\'qnumber-hidden\'></div><p class="question">Most students were able to secure some marks on the truth table with over half securing full marks. Where marks were dropped students tended to not follow a logical sequence of steps to calculate NOT B, then NOT A, leading to A OR (NOT B), (NOT A) AND B and then finally NOT ((NOT A) AND B).</p></h5>', 'notes': '', 'resources': ''}}
User: Now, the user will ask questions after this message. Use everything I gave you and the knowledge you have acquired, and from the notes you made, to answer their question in a very concise way that WILL score ALL marks. Just like the notes. For this, your answer will not have the same structure as the revision notes. Think of it as answering an exam question: short, consice, useful, scores ALL marks. Just like the exam questions provided to you, you will not leave your response in a 'notes' manner. You are just answering an exam question: which means it has to be very short unless explicitly specified by the user that it must be long and detailed. So, keep it short, concise, and only a couple of sentences that score ALL marks. Remember, it is an A-Level exam question and you will style it as such: incredibly concise sentences (essentially like bullet points but without the bullet points) that score marks. Most sentences won't even have commas, this does not mean you can't use them. Also do not repeat the question in your answer, just do it. Score all marks, assume how many marks there are based on the question if it is not provided to you. Imagine that for every sentence you make, you score a mark (for simpler questions), for high (>5 mark) questions that may differ.
In summary, you must:
* Answer very concisely. Kind of like bullet points but as a short para. Most of the time, a sentence, or point, will be a mark.
* Do not repeat the question at the start.
* Don't over-do your answer. Please. 1 mark (e.g., usually, 'What' questions) is like one very short sentence usually. Remember the summary from the notes? Your answer will essentially be like that for most questions but a bit (a bit!) more developed. Remember, this is just A-Levels. Use some of the exam questions that I provided as an example of how you should model your answers.
* When you're listing examples, don't list every example in the universe.
* Score all marks. Be helpful.
User: Write the notes you made. Exam Qustions must include the FULL content and answer that scores full marks, no. of marks should also be included.
Assistant: