Unit 1: A1 Computer fundamentals
Topic 1.2: Data representation and logic Questions
Practice 20 exam-style questions for IB Computer Science Topic 1.2. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.
1Suggest2 marks
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A circuit has inputs A, B and C and its truth table shows X = 1 in exactly four rows. Suggest what this indicates about the expression.
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Unlock Question2Choose1 mark
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Choose the number of rows in a truth table for a circuit with five inputs.
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Unlock Question3Explain3 marks
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Explain how a truth table helps a programmer write a correct if-statement with two conditions.
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Unlock Question4Describe2 marks
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Describe the logic diagram needed for X = A AND B.
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Unlock Question5Describe1 mark
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Describe the logic diagram needed for X = NOT A.
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Describe the logic diagram needed for X = A AND NOT B.
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Describe the logic diagram needed for X = NOT (A AND B).
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Unlock Question8Construct2 marks
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Construct the expression represented by this circuit: A and B feed an OR gate; the output of that OR gate and input C feed an AND gate, whose output is X.
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Unlock Question9Construct2 marks
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Construct the expression represented by this circuit: A feeds a NOT gate; the output of that NOT gate and input B feed an OR gate, whose output is X.
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Explain why the diagram for X = A OR B AND C depends on which operator is applied first.
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Unlock Question11State1 mark
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State the number of gates needed for the circuit X = NOT (A OR B), using the smallest number of standard gates.
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Determine the smallest number of gates needed for X = NOT A AND NOT B.
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Describe how a half adder is built from logic gates.
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Explain why a half adder cannot be used on its own to add multi-bit binary numbers.
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Unlock Question15Determine2 marks
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A circuit feeds A and B into a NAND gate, and the NAND output into a NOT gate. Determine the single gate that behaves identically.
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A circuit feeds A into a NOT gate and B into a NOT gate, then feeds both NOT outputs into a NAND gate. Determine the single gate that behaves identically.
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Unlock Question17Outline2 marks
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Outline one advantage of drawing a logic diagram rather than writing the Boolean expression.
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Outline one advantage of the Boolean expression over the logic diagram.
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A logic diagram uses six gates. Suggest how an engineer might reduce that number.
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Explain why reducing the gate count of a circuit matters in a manufactured product.
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