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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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4 questions · 7 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.

2Describe2 marksTranslators Swap Remove

A high-level program must be translated into machine code before it can be run.

Describe how a compiler and an interpreter differ in when the translated code is executed.

[2 marks]
Mark scheme

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

  • The interpreter executes each line as soon as it has been translated (1) so translation and execution happen together/at the same time (1)
  • The compiler translates the whole program first (1) and the machine code is run later/separately (1)
  • The interpreter translates the code and runs it while the program is running (1) whereas the compiler does not run the code it produces (1)
  • The compiler produces translated code that is executed only after all the translation has finished (1) but the interpreter executes each line immediately (1)

Allow 'translates one line at a time' where it is linked to executing each line immediately.

Do not accept answers that only state that a compiler is faster/an interpreter is slower, without reference to when execution happens.

Do not accept answers that only give object code, error reporting or portability, without reference to when execution happens.

Do not accept the compiler executing the program as it translates it.

Example answers and how they were marked
Full marks2/2

The compiler translates the code first and the program is executed afterwards, but the interpreter executes each line as soon as it has been translated.

Why: Compiler translates the whole program first and it is executed afterwards (1) and interpreter executes each line as soon as it is translated (1).

Some marks1/2

The interpreter executes each line immediately after translating it.

Why: Correct interpreter timing (1); no comparison with when the compiler's translated code is executed.

No marks0/2

The compiler executes the program line by line as it translates it.

Why: Reverses the two translators; a compiler does not execute the program it translates, so no mark.

3Explain2 marksLow and High Level Languages Swap Remove

High-level languages are designed to be easier to learn than low-level languages.

Explain one reason why a high-level language is easier to learn than a low-level language.

[2 marks]
Mark scheme

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

  • Statements are written in English-like words/use maths symbols (1) so the programmer can understand more easily what each one does (1)
  • The language uses meaningful names for variables/structured constructs such as loops (1) so the code is easier to read/follow (1)
  • One statement translates into several machine code instructions (1) so there are fewer instructions to learn/understand for the same task (1)

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

Do not accept 'it is easier' / 'it is simpler' on its own, without saying what is easier/simpler.

Do not accept 'the computer understands it directly' / 'it does not need translating'.

Do not award answers about the program running faster or using less memory, as these are not about ease of learning.

Example answers and how they were marked
Full marks2/2

Statements are written in English-like words (1) so the programmer can understand more easily what each line does (1).

Why: Linked point (1) of English-like statements and reason (1) that these are easier to understand.

Some marks1/2

It uses meaningful names for variables (1) so it is easier.

Why: Point (1) that meaningful names for variables are used, but 'so it is easier' is not accepted as the linked reason.

No marks0/2

Because the computer can understand high-level code without translation.

Why: Misconception that high-level code is understood directly by the computer; no creditworthy characteristic of the language is given.

4Explain2 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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