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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 604 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 markCharacter Sets Swap Remove

Characters are encoded using 7-bit ASCII.

Identify the number of different characters that can be represented using 7-bit ASCII.

[1 mark]
  • A64
  • B127
  • C128
  • D256
Mark scheme
  • C 128 (1)
  • The only correct answer is C. The correct answer is 128.
  • A is not correct because 6 bits give only 64 different combinations
  • B is not correct because 127 is the largest 7-bit value, not the number of characters that 7 bits can represent
  • D is not correct because 256 characters need 8 bits, as used by 8-bit extended ASCII
Example answers and how they were marked
Full marks1/1

C 128

Why: Selects the only correct option (1): 7 bits give 2 to the power of 7, which is 128 different characters.

No marks0/1

D 256

Why: Near miss scoring 0: 256 is the number of characters that 8 bits give in extended ASCII, not 7-bit ASCII.

No marks0/1

B 127

Why: Misconception scoring 0, the off-by-one error the examiners' report describes: 127 is the largest 7-bit value, but 7 bits give 128 different characters.

2Short recall2 marksStored Program Computers Swap Remove

The central processing unit (CPU) contains an arithmetic logic unit (ALU).

State two types of operation carried out by the ALU.

[2 marks]
Mark scheme

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

  • An arithmetic operation, e.g. addition/subtraction/multiplication/division (1)
  • A logical operation, e.g. comparing two values (is A > B?) / using AND, OR, NOT (1)

Do not accept decoding instructions, fetching instructions or controlling the timing of the CPU, as these are carried out by the control unit.

Example answers and how they were marked
Full marks2/2

It carries out arithmetic operations such as addition and subtraction, and logical operations such as comparing two values to see if one is greater than the other.

Why: Arithmetic operation (1) and logical operation (1).

Some marks1/2

It adds numbers together and works out the result.

Why: Arithmetic operation, addition (1). No logical operation.

No marks0/2

It decodes the instructions that have been fetched from main memory.

Why: Decoding and fetching are the control unit's role; the mark scheme's do-not-accept line covers this.

3Describe2 marksMemory Management Swap Remove

An operating system keeps a record of the memory it has allocated to each program.

Describe how this record is used.

[2 marks]
Mark scheme

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

  • The start and end address/size of the block allocated to each program is recorded (1) so the operating system knows which areas of main memory are in use and which are free (1)
  • The record is checked before memory is allocated (1) so memory already in use is not given to another program/is not overwritten (1)
  • The record is searched for a free block that is large enough (1) so a newly loaded program is placed in a suitable area of main memory (1)
  • The record is updated when a program ends/closes (1) so the memory it was using is marked as free for other programs (1)

Allow the record to be called a memory map/memory table/allocation table.

A response that only says the operating system keeps a record/list of the memory each program is using, without saying what the record contains, earns 0 marks.

A response that states what the record contains, e.g. the addresses/the start and end address of each block, earns 1 mark even if it does not say how the record is used.

Do not accept responses about saving programs/files to secondary storage or about moving programs to virtual memory, as these are not uses of this record.

Example answers and how they were marked
Full marks2/2

The operating system records the start and end address of the block of memory given to each program so that it does not give the same memory to another program.

Why: The start and end address of each block is recorded (1) linked to memory already in use not being given to another program (1).

Some marks1/2

The operating system records the start and end address of the memory used by each program.

Why: States what the record contains (1), but does not develop how the record is used, so the second mark is not earned.

No marks0/2

The operating system saves the programs to the hard disk so there is enough memory for other programs.

Why: Describes moving programs to secondary storage rather than how the record of allocated memory is used; no creditworthy point is made.

4Explain2 marksProtocols & Layers Swap Remove

A bank's website can use HTTP or HTTPS.

Explain one benefit to a customer of the bank's website using HTTPS.

[2 marks]
Mark scheme

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

  • Data is encrypted/scrambled (1) so it cannot be read/understood if it is intercepted (1)
  • The customer's bank/personal details are kept secure/private (1) because the data is encrypted/scrambled during transmission (1)
  • The customer's login details/password cannot be read by an eavesdropper (1) because HTTPS encrypts/scrambles the data sent to and from the web server (1)

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

Allow 'scrambled' as an alternative to 'encrypted'.

Do not accept 'it is more secure/safe' or 'the data is secure' on its own, without saying how it is made secure (e.g. encryption/scrambling).

Do not accept faster loading/speed, or claims that HTTPS stops viruses or always proves the website is genuine.

Example answers and how they were marked
Full marks2/2

The data is encrypted (1) so anyone intercepting it cannot read the customer's bank details (1).

Why: Linked point (1) and reason (1): encryption means intercepted data cannot be read.

Some marks1/2

The data is encrypted (1) so the website is secure.

Why: Point (1) for encryption, but 'secure' on its own is a near-miss that the mark scheme does not credit as the linked reason; it must say why, e.g. that intercepted data cannot be read.

No marks0/2

HTTPS is faster than HTTP (0) so the customer can log in more quickly.

Why: Speed is not a benefit of HTTPS and is named in a 'Do not accept' line, so no creditworthy point is given.

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