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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 markImages Swap Remove

Identify the term for the number of bits used to store the colour of each pixel.

[1 mark]
  • AColour depth
  • BImage size
  • CResolution
  • DStorage size
Mark scheme
  • A Colour depth (1)
  • The only correct answer is A. The correct answer is colour depth.
  • B is not correct because image size is the width and height of the image in pixels
  • C is not correct because resolution is the number of pixels per unit length, such as pixels per inch
  • D is not correct because storage size is the amount of storage the image file uses
Example answers and how they were marked
Full marks1/1

A Colour depth

Why: Correct option; colour depth is the number of bits used to store the colour of each pixel (1).

No marks0/1

B Image size

Why: Image size is the width and height of the image in pixels, not the number of bits used per pixel; no mark.

No marks0/1

D Storage size

Why: Storage size is the amount of storage the image file uses, not the colour depth; no mark.

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.

3Short recall1 markUnits & Conversion Swap Remove

A file has a size of 2 kibibytes.

State the number of bytes in the file.

[1 mark]
Mark scheme

Award one mark for:

  • 2048 (1)
  • 2 × 1024 (1)
  • 2^11 (1)

Allow 2048 bytes.

Do not accept 2000, which is the number of bytes in two decimal kilobytes.

Do not accept 1024, which is the number of bytes in one kibibyte.

Do not accept 16, which is the number of bits in two bytes.

Example answers and how they were marked
Full marks1/1

2048

Why: 2048 is 2 × 1024, the number of bytes in 2 kibibytes (1).

No marks0/1

2000

Why: 2000 uses the decimal kilobyte, not the binary kibibyte; the mark scheme does not accept it.

No marks0/1

16

Why: 16 is the number of bits in two bytes, confusing bits with bytes; the mark scheme does not accept it.

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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