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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 recall1 markCompression Swap Remove

A company backs up its files to an external hard drive.

Give one reason why the company compresses the files before backing them up.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • More files/data can be stored (in the same storage space) (1)
  • The files take up less storage space (1)
  • The backup is quicker/faster to complete (1)
  • Less data needs to be transferred to the backup device (1)

Do not accept 'makes the files more secure' or 'encrypts the files'.

Example answers and how they were marked
Full marks1/1

The compressed files take up less storage space, so more files can be backed up.

Why: The files take up less storage space (1).

No marks0/1

It reduces the amount of disk fragmentation.

Why: Near-miss: compression does not reduce disk fragmentation.

No marks0/1

It encrypts the files so they are safer if the drive is stolen.

Why: Misconception: compression does not encrypt files, and security is not accepted.

3Explain2 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.

4Calculate3 marksAdding Binary Numbers Swap Remove

Binary patterns can represent numbers.

(a)

Complete the table to show the 8-bit result of the binary addition.

[2 marks]
1286432168421
11011011
11011100
Mark scheme

Award one mark for each correct nibble in the correct order:

  • 1011 (1)
  • 0111 (1)

0 marks if the response is not 8-bit binary.

Ignore a carry shown beyond the eighth bit.

Example answers and how they were marked
Full marks2/2

1011 0111

Why: 219 + 220 = 439, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0000 0111

Why: Forgets to carry the 1s. The second nibble is correct (1); the first is not.

No marks0/2

1101 1111

Why: Never carries. Neither nibble is correct.

(b)

State the name of the error that occurs when this addition is carried out.

[1 mark]
Mark scheme

Award one mark for:

  • overflow (error) (1)
Example answers and how they were marked
Full marks1/1

Overflow

Why: The result needs more bits than are available (1).

No marks0/1

Underflow

Why: A near miss: the result is too big for 8 bits, not too small.

No marks0/1

A syntax error

Why: A syntax error is a mistake in a program's code, not in arithmetic.

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