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.

Practice paper

10 questions · 18 marks

Pick again

1Short recall1 markBinary and Hexadecimal Basics Swap Remove

Computers use binary patterns to represent data.

State the number of different values that can be represented by a 4-bit binary pattern.

[1 mark]

Mark scheme

Award one mark for:

16 (1)

Allow 2^4, 2 × 2 × 2 × 2 or any expression that evaluates to 16.

Allow sixteen (in words).

Do not accept 15.

Example answers and how they were marked

Full marks1/1

Why: Correct number of different values for a 4-bit binary pattern (1).

No marks0/1

Why: Gives the number of values for a 5-bit pattern, not a 4-bit pattern, so no creditworthy point is present.

No marks0/1

Why: Gives the largest value a 4-bit pattern can hold, not the number of different values; the mark scheme does not accept 15.

2Convert1 markDenary to Hexadecimal Conversion Swap Remove

Computer systems manipulate bit patterns.

Convert the hexadecimal number D5 to denary.

[1 mark]

Mark scheme

Award one mark for:

213 (1)

Example answers and how they were marked

Full marks1/1

213

Why: 13 × 16 + 5 = 213 (1).

No marks0/1

Why: Takes the right-hand digit as the 16s, so the value is wrong.

No marks0/1

Why: Adds the two digits instead of multiplying the first by 16.

3Short recall2 marksBinary and Hexadecimal Basics Swap Remove

A computer stores a photograph as a binary pattern.

State two reasons why computers use binary to represent data.

[2 marks]

Mark scheme

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

Computer components/hardware have two states, on and off (1)
Digital circuits/switches/transistors have two stable states (1)
Two states are easy to distinguish/detect reliably (1)
Fewer errors occur because only two voltage levels need to be recognised (1)
Binary is simple to implement in hardware because only two states/two voltage levels are needed (1)
Binary is cheaper to build than a system with more states, as fewer components/levels are needed (1)

Award a maximum of one mark for reasons about reliability/errors, however they are phrased (e.g. 'two states are easy to distinguish' and 'less chance of error' are the same reason).

Do not accept 'it is simple' or 'it is cheap' without a justification.

Do not accept 'computers only understand 1s and 0s' on its own.

Do not accept a restatement of the stem or of the question, e.g. 'computers use binary to store data' or 'because that is how data is stored', with no reason given.

Example answers and how they were marked

Full marks2/2

Computer components are switches that have two states, on and off. Two states are easy to tell apart, so there is less chance of error.

Why: Gives two creditworthy reasons: components have two on/off states (1) and two states are easy to distinguish (1). The 'less chance of error' comment is the same reliability reason, so it does not earn a third mark but the first two stand.

Some marks1/2

Computers use switches that are either on or off.

Why: Gives one creditworthy reason: hardware/components have two on/off states (1). No second reason.

No marks0/2

Computers only understand 1s and 0s.

Why: This is a vague statement, not a reason why binary is used; the mark scheme does not accept it on its own.

4Explain2 marksBinary and Hexadecimal Basics Swap Remove

A traffic light controller uses a 5-bit binary pattern to store the state of its lights.

Explain why this pattern can represent a maximum of 32 different states.

[2 marks]

Mark scheme

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

Each bit has two possible values, 0 and 1 (1) so the five bits give 2 × 2 × 2 × 2 × 2/2^5 = 32 different combinations/states (1)
Because each of the five bits can be either 0 or 1 (1) there are 2^5/2 × 2 × 2 × 2 × 2 = 32 different combinations/states (1)
Each extra bit doubles the number of combinations/states (1) so five bits give 2^5 = 32 states (1)

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

Do not award a response that only repeats the 32 states given in the question, such as 'it can represent 32 states' or '2^5 = 32', without a reason about each bit having two possible values.

Do not accept 2 × 5 = 10 as the calculation; the number of states doubles with each extra bit.

Do not accept 31/0 to 31 as the number of states; 31 is the largest value five bits can store, not the number of states.

Example answers and how they were marked

Full marks2/2

There are 32 different states because each of the 5 bits has two possible values, 0 and 1, so the number of combinations is 2 × 2 × 2 × 2 × 2 = 32.

Why: Point that each bit has two possible values, 0 and 1 (1), linked to the calculation 2 × 2 × 2 × 2 × 2 = 32 states (1).

Some marks1/2

Each bit has two possible values, 0 and 1.

Why: Gives the point that each bit has two possible values (1) but does not link it to 2^5 = 32, so the second mark is not earned.

No marks0/2

It can represent 32 states because the highest number it can store is 31.

Why: Only repeats the 32 states from the question and gives the common misconception that 31 is the number of states; there is no reason about each bit having two possible values, so no marks.

5Explain2 marksBinary and Hexadecimal Basics Swap Remove

A computer stores a colour as a 24-bit binary pattern.

The programmer writes the colour in hexadecimal rather than in binary. Explain one reason why.

[2 marks]

Mark scheme

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

Hexadecimal is shorter/has fewer digits than binary (1) because each hexadecimal digit represents 4 bits/a nibble (1)
Hexadecimal is easier to read/write (1) because there are fewer characters/digits to enter (1)
Hexadecimal is easier to convert to and from binary (1) because four binary bits map to one hexadecimal digit (1)

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

Allow the 24-bit colour as the linked reason, e.g. a 24-bit value can be written as only 6 hexadecimal digits (1).

Do not accept 'easier'/'simpler' on its own: naming what is easier, such as easier to read/write, is the first mark, but the second mark needs a linked reason.

Only credit 'fewer digits/characters' once, as the reason for one point; do not award it again as the reason for a second point.

Do not accept that hexadecimal uses less storage space/memory than binary, or that it is more compact to store; the same number of bits is stored.

Example answers and how they were marked

Full marks2/2

Hexadecimal is shorter than binary because each hexadecimal digit represents 4 bits, so the 24-bit colour needs only 6 hexadecimal digits.

Why: Gives the point that hexadecimal is shorter (1) and links it to each hexadecimal digit representing 4 bits, using the 24-bit colour as the linked reason (1).

Some marks1/2

Hexadecimal is easier to read than binary.

Why: Names what is easier to read (1) but gives no linked reason such as fewer digits to enter, so only one mark.

No marks0/2

Hexadecimal is used because it takes up less storage space than binary.

Why: The same number of bits is stored in either notation, so this is a misconception and earns no mark.

6Convert2 marksDenary to Binary Conversion Swap Remove

Binary patterns can represent numbers.

Convert the denary number 199 to 8-bit binary.

[2 marks]

Mark scheme

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

1100 (1)
0111 (1)

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

Example answers and how they were marked

Full marks2/2

1100 0111

Why: 199 = 128 + 64 + 4 + 2 + 1: both nibbles are correct (2).

Some marks1/2

1100 1000

Why: Converts 200 instead (a slip in adding up the place values). The first nibble is correct (1); the second is not.

No marks0/2

1110 0011

Why: The bits are written in reverse, smallest place value first. Neither nibble is correct.

7Convert2 marksDenary to Negative Binary Conversion Swap Remove

Computer systems manipulate bit patterns.

Convert the 8-bit binary two's complement pattern 1100 1011 to denary.

[2 marks]

Mark scheme

Award one mark for each of:

− (negative sign) (1)
53 (1)

The correct answer is −53

Example answers and how they were marked

Full marks2/2

−53

Why: The left-hand bit is worth −128: −128 + 75 = -53. Sign (1) and value (1).

Some marks1/2

Why: The value is right (1) but the minus sign is missing.

No marks0/2

203

Why: Reads it as an unsigned number, so neither the sign nor the value is right.

8Convert2 marksHexadecimal to Binary Conversion Swap Remove

Binary, denary and hexadecimal patterns represent numbers.

Convert the hexadecimal number B7 to 8-bit binary.

[2 marks]

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.

Example answers and how they were marked

Full marks2/2

1011 0111

Why: Each digit is 4 bits: B = 1011, 7 = 0111 (2).

Some marks1/2

1011 1000

Why: Converts 7 as if it were the next digit up. The first nibble is correct (1); the second is not.

No marks0/2

0111 1011

Why: The nibbles are in the wrong order. Neither nibble is correct.

9Calculate2 marksAdding Binary Numbers Swap Remove

Computers manipulate binary patterns.

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

[2 marks]

128	64	32	16	8	4	2	1
1	0	0	1	0	1	0	1
0	1	0	0	1	1	1	1

Mark scheme

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

1110 (1)
0100 (1)

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

Example answers and how they were marked

Full marks2/2

1110 0100

Why: 149 + 79 = 228, carrying where a column adds to 2: both nibbles are correct (2).

Some marks1/2

1110 0101

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

1101 1111

Why: Writes 1 in every column with a 1 and never carries. Neither nibble is correct.

10Calculate2 marksBinary Shifts Swap Remove

Computers manipulate binary patterns.

Complete the table with the result of applying the shift to the binary pattern.

[2 marks]

Binary pattern	Shift	8-bit binary result
1000 0001	Logical shift right by 1

Mark scheme

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

0100 (1)
0000 (1)

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

Example answers and how they were marked

Full marks2/2

0100 0000

Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).

Some marks1/2

0100 0001

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

0000 0010

Why: Shifts the bits the wrong way. Neither nibble is correct.

Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a paper

Practice paper

Questions by topic

2.1 Binary

2.2 Data representation

2.3 Data storage and compression

3.1 Hardware

3.2 Software

3.3 Programming languages

4.1 Networks

More ways to revise Edexcel GCSE Computer Science (1CP2)