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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 631 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 · 7 marks

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1Multiple choice1 markTranslators Swap Remove

An interpreter translates high-level code differently from a compiler.

Identify what an interpreter does immediately after translating a line of code.

[1 mark]
  • AExecutes the line
  • BProduces the object code
  • CSaves the line to a file
  • DTranslates the next line
Mark scheme
  • A Executes the line (1)
  • The only correct answer is A. The correct answer is that the interpreter executes the line.
  • B is not correct because an interpreter does not produce object code; that is what a compiler does
  • C is not correct because an interpreter does not save the translated code to a file
  • D is not correct because the interpreter executes the current line before it translates the next line
Example answers and how they were marked
Full marks1/1

A Executes the line

Why: Selected the line being executed straight after translation, which is how an interpreter works (1).

No marks0/1

D Translates the next line

Why: Near miss: the interpreter executes the translated line first and only then moves on to translate the next line, so no mark.

No marks0/1

B Produces the object code

Why: Confuses interpretation with compilation: object code is produced by a compiler, not an interpreter, so no mark.

2Short recall2 marksTranslators Swap Remove

An interpreter is a type of translator.

Define the term interpreter.

[2 marks]
Mark scheme

Award one mark for any of the following up to a maximum of two marks:

  • Translates/converts (high-level/source) code one line/statement at a time (1)
  • Translates/converts the code and executes/runs each line as it goes (1)
  • Executes/runs each line/statement immediately after it is translated (1)
  • Reports/stops with an error message as soon as a syntax error is found (1)

Allow 'runs' for executes, 'converts' for translates and 'instruction' for line/statement

Do not accept translates the whole program before it is run

Do not accept produces/creates object code, an executable file or machine code that is saved

Example answers and how they were marked
Full marks2/2

An interpreter is a program that translates high-level code line by line. Each line is run as soon as it has been translated, so any errors are shown straight away.

Why: Line-by-line translation (1) and each line executed immediately (1); the point about errors would be a third creditworthy point but the maximum is two.

Some marks1/2

An interpreter translates code one line at a time.

Why: Line-by-line translation (1); no point for immediate execution.

No marks0/2

An interpreter translates the whole program before it is run.

Why: Near-miss describing a compiler; the scheme's 'Do not accept' line rules out whole-program translation.

3Describe2 marksTranslators Swap Remove

Source code can contain syntax errors.

Describe how a compiler and an interpreter differ in the way they deal with syntax errors.

[2 marks]
Mark scheme

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

  • The compiler reports all syntax errors after translation has finished (1) whereas the interpreter stops at the first error it finds (1)
  • The interpreter reports a syntax error as soon as it finds one (1) and does not translate/execute any more of the program (1)
  • The compiler continues translating after an error (1) and reports the errors at the end (1)
  • The interpreter stops translating when it reaches an error (1) but the compiler finishes translating before reporting errors (1)

Do not accept answers about fixing/correcting errors or about object code.

Do not award 'the compiler finds more errors' without saying errors are reported at the end.

Example answers and how they were marked
Full marks2/2

A compiler reports all the syntax errors at the end of translation, whereas an interpreter stops and reports the error as soon as it finds one.

Why: Compiler reports errors at the end (1) and interpreter stops/reports at the first error (1).

Some marks1/2

An interpreter stops translating when it finds a syntax error.

Why: Interpreter stops at the first error (1); no comparison with when the compiler reports errors.

No marks0/2

A compiler reports a syntax error immediately, before translating the rest of the program.

Why: Reverses the compiler's behaviour; it finishes translating before reporting errors.

4Explain2 marksTranslators Swap Remove

An interpreter translates and executes high-level code.

Explain why an interpreted program must be translated again each time it is run.

[2 marks]
Mark scheme

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

  • No object code/machine code file is stored/saved (1) so there is no translated program to run on the next occasion (1)
  • The translation is only temporary/is lost when the program ends (1) because each line is translated as the program runs (1)
  • No executable file is created/saved (1) so the whole program has to be translated again every time it is run (1)
  • The interpreter translates each line while the program is running (1) so nothing is kept that could be run without the interpreter (1)

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

Do not accept 'it is interpreted' or 'it is not compiled' without saying that no object code/executable is stored/saved.

Do not accept 'the source code is high-level so it must be translated' or 'the source code has to be turned into machine code' on its own, as this is true of any translation.

Do not accept answers about the source code being deleted.

Example answers and how they were marked
Full marks2/2

The interpreter does not store an object code file, so there is no machine code file to run on the next occasion.

Why: No object code stored (1) linked to no translated program for the next run (1).

Some marks1/2

No object code is saved.

Why: Point that nothing is stored (1) but no linked reason saying why this means the program must be translated again.

No marks0/2

It has to be translated again because the interpreter deletes the source code after each run.

Why: Incorrect: the interpreter does not delete the source code; no mark scheme point.

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