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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

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4 questions · 6 marks

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1Multiple choice1 markTranslators Swap Remove

A program contains a syntax error. An interpreter reports the error as soon as it finds it.

Identify when a compiler reports the syntax errors it finds in the source code.

[1 mark]
  • AAfter each line is translated
  • BAt the end of translating the program
  • CWhen the first error is found
  • DWhen the object code is run
Mark scheme
  • B At the end of translating the program (1)
  • The only correct answer is B. The correct answer is at the end of translating the program.
  • A is not correct because a compiler translates the whole program and does not report an error after each line; reporting after each line is how an interpreter behaves
  • C is not correct because a compiler does not stop at the first error; it finishes translating and reports the errors it finds at the end
  • D is not correct because syntax errors are found during translation, before the object code is run
Example answers and how they were marked
Full marks1/1

B At the end of translating the program

Why: Chosen option states that errors are reported once the whole program has been translated, as a compiler does (1).

No marks0/1

A After each line is translated

Why: Near miss: reporting an error after each line is the behaviour of an interpreter, not a compiler, so no mark.

No marks0/1

C When the first error is found

Why: Misconception that a compiler stops and reports at the first error it finds; a compiler reports the errors at the end of translation, so no mark.

2Short recall1 markLow and High Level Languages Swap Remove

A high-level language uses statements that look like English or maths.

State what a single statement in a high-level language is usually translated into.

[1 mark]
Mark scheme

Award one mark for:

  • Several/multiple machine code instructions (1)

The answer must refer to instructions.

Do not accept machine code on its own.

Do not accept binary on its own.

Do not accept 'one or more machine code instructions' as it does not show that one statement becomes several instructions.

Do not accept assembly code/compiled code/low-level code on their own.

Do not accept 'a line of code'/'a statement' as this repeats the question.

Example answers and how they were marked
Full marks1/1

Several machine code instructions

Why: Matches the creditworthy point that one high-level statement translates into several machine code instructions (1).

No marks0/1

Machine code

Why: Near-miss: gives the type of code but not that one statement becomes several instructions; mark scheme does not accept machine code on its own.

No marks0/1

Binary

Why: Misconception: high-level statements are translated into machine code instructions, not just binary; not accepted.

3Explain2 marksLow and High Level Languages Swap Remove

A programmer writes the same program in a low-level language and in a high-level language.

Explain one reason why the program written in the low-level language may run faster.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • The programmer can choose the most efficient instructions/registers to use (1) so the program completes its task in fewer steps (1)
  • The programmer can optimise the code for the processor (1) because low-level instructions give direct control of registers/memory (1)
  • Each low-level instruction maps to one machine code instruction (1) so fewer instructions are executed than for the equivalent high-level code (1)
  • The translated code is smaller (1) so fewer instructions are fetched from memory and executed (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'it is low-level' / 'it is closer to machine code' / 'low-level code is faster' on its own without a reason why it makes the program run faster.

Do not accept 'high-level code has to be translated' / 'high-level code is interpreted' on its own without saying why that makes the program slower.

Do not accept 'the code is smaller' on its own without saying that this means fewer instructions are fetched/executed.

Do not accept 'it is easier to write' or 'quicker to type' as a reason for faster execution.

Example answers and how they were marked
Full marks2/2

The programmer can choose the most efficient instructions and registers to use so the program completes its task in fewer steps.

Why: Linked point (1) of choosing efficient instructions/registers and reason (1) that the task is completed in fewer steps, so it runs faster.

Some marks1/2

Each low-level instruction maps to one machine code instruction so the program is shorter to type.

Why: Point (1) that one low-level instruction maps to one machine code instruction, but being shorter to type does not explain why the program runs faster, so no second mark.

No marks0/2

Because it is closer to machine code.

Why: 'Closer to machine code' alone gives no reason why that makes the program run faster, and the mark scheme does not accept it on its own.

4Explain2 marksTranslators Swap Remove

An interpreter translates a program one line at a time.

Explain why an interpreted program stops when it reaches a line that contains a syntax error.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • The interpreter translates and executes each line in turn (1) so it cannot continue past a line it cannot translate (1)
  • The interpreter finds the error when it reaches that line (1) so it stops and displays an error message before later lines are executed (1)
  • Each line is translated just before it is executed (1) so a syntax error in that line prevents that translation/execution from happening (1)
  • The interpreter does not translate the whole program first (1) so it only discovers the error when that line is reached during execution (1)

For both marks, the expansion must follow/associate with the statement.

Do not accept 'the program crashes' without saying that the interpreter cannot translate/execute the line.

Do not accept answers about how a compiler reports errors.

Example answers and how they were marked
Full marks2/2

The interpreter translates each line just before it executes it, so when it reaches the line with the syntax error it cannot translate that line and stops.

Why: Line-by-line translation (1) linked to being unable to translate the faulty line, so stopping (1).

Some marks1/2

The interpreter translates one line at a time, so it stops at the error.

Why: Line-by-line translation (1); 'stops at the error' repeats the outcome and does not explain why it cannot continue.

No marks0/2

It stops because the compiler reports all errors at the end.

Why: Describes a compiler, not an interpreter; no credit.

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