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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 514 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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5 questions · 9 marks

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1Short recall1 markTranslators Swap Remove

An interpreter translates high-level code.

State what happens to the translation of a program when an interpreter finds a syntax error.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • Translation/execution stops (when the error is found) / the rest of the program is not translated/executed (1)

Allow stops/terminates/halts when the error is found

Do not accept shows/displays an error message on its own

Do not accept the whole program is translated and errors are reported at the end

Do not accept translates line by line on its own

Example answers and how they were marked
Full marks1/1

The translation stops as soon as the error is found, so the rest of the program is not translated.

Why: Translation stops when the error is found (1).

No marks0/1

An error message is displayed.

Why: Only an error message; it does not say translation stops, and the scheme does not accept a displayed error message on its own.

No marks0/1

The whole program is translated and all the errors are reported at the end.

Why: Describes a compiler; the scheme does not accept errors being reported at the end of translating the whole program.

2Short recall2 marksLow and High Level Languages Swap Remove

Programs written in a high-level language are often machine independent.

Define the term machine independence.

[2 marks]
Mark scheme

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

  • The (same) program/source code can run on different types/makes of computer/processor (1)
  • With few/no changes (to the program code) (1)
  • The same source code can be translated for each type of processor (1)
  • A different compiler/interpreter is used for each type of processor (1)
  • The program does not depend on one specific type of processor/hardware (1)
  • Only one version of the program needs to be written/kept (1)
  • The program is portable between different computers (1)

Allow 'different computers' as meaning different types of computer/processor.

Do not accept a program that will only run on one type of computer / the computer it was written on.

Do not accept written in machine code/binary, is translated into machine code, compiled/interpreted, is a low-level language.

Example answers and how they were marked
Full marks2/2

The same program can run on different types of computer (1) without being changed (1).

Why: Two creditworthy parts: runs on different types/makes of computer/processor (1); with few/no changes (1).

Some marks1/2

A program can run on different computers.

Why: Creditworthy point: can run on different types/makes of computer/processor (1), with 'different computers' allowed by the guidance. No second part about changes or translation.

No marks0/2

A program is written in machine code so the computer can understand it.

Why: Misconception: machine code is not machine independence; the mark scheme does not accept this, and no other creditworthy point is given.

3Short 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.

4Explain2 marksTranslators Swap Remove

A programmer writes a program in a high-level language. The program is translated by a compiler.

Explain why a compiler must translate the whole program before any of it can be executed.

[2 marks]
Mark scheme

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

  • The compiler produces object code/machine code for the whole program (1) so there is no complete executable until every line has been translated (1)
  • The compiler translates all the source code before producing the object code (1) so the program cannot start until translation has finished (1)
  • The compiler checks the whole program for errors during translation (1) so all of the source code must be read before an executable can be produced (1)

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

Allow 'in one go'/'all at once' for the translation point, but this does not earn the second mark unless it is linked to why the program cannot be executed until translation has finished.

A statement that the whole program is translated, with no linked reason about when the program can be executed, earns 1 mark only.

Do not accept 'a compiler is faster' or 'compiled code runs faster' on its own; this does not explain why translation must finish before execution.

Do not accept 'it translates and runs the program one line at a time', as this describes an interpreter.

Example answers and how they were marked
Full marks2/2

A compiler produces object code for the whole program, so there is no complete executable until every line has been translated.

Why: Object code for the whole program (1) linked to there being no complete executable until every line is translated (1).

Some marks1/2

A compiler translates the whole program in one go.

Why: Translation of the whole program only (1); no linked reason about when the program can be executed, so the second mark is not awarded.

No marks0/2

A compiler translates and runs the program one line at a time, so it stops when it finds an error.

Why: Confuses a compiler with an interpreter; nothing about translating the whole program before execution, so no creditworthy point.

5Explain2 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 (1) so the program completes its task in fewer steps (1).

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 (1) 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.

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