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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 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 markStored Program Computers Swap Remove

Identify the function of the control unit in the fetch-decode-execute cycle.

[1 mark]
  • ADecodes instructions
  • BPerforms arithmetic operations
  • CStores data and instructions
  • DTemporarily stores data being processed
Mark scheme
  • A Decodes instructions (1)
  • The only correct answer is A. The correct answer is Decodes instructions.
  • B is not correct because the arithmetic logic unit performs arithmetic operations
  • C is not correct because main memory stores data and instructions
  • D is not correct because registers temporarily store data being processed
Example answers and how they were marked
Full marks1/1

A Decodes instructions

Why: Correct option: the control unit decodes instructions during the fetch-decode-execute cycle (1).

No marks0/1

C Stores data and instructions

Why: Main memory stores data and instructions, not the control unit; this is a common distractor, so no mark.

No marks0/1

B Performs arithmetic operations

Why: Arithmetic operations are performed by the ALU, not the control unit; a common confusion between CPU components, so no mark.

2Short recall2 marksSecondary Memory Swap Remove

Computers have both primary storage and secondary storage.

Define the term secondary storage.

[2 marks]
Mark scheme

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

  • (Storage that is) non-volatile / keeps its data when the power is turned off (1)
  • (Storage that is) used to store programs and data/files (for later use) (1)
  • (Storage that is) not directly accessible by the CPU / not directly accessed by the CPU (1)

Allow both the non-volatile point and the stores programs and data point from one sentence if each idea is clearly stated, e.g. 'non-volatile storage that holds programs and data'.

Allow accessed via the CPU / must be copied into RAM before the CPU can use it for the third point.

Do not accept volatile / loses its data when the power is turned off.

Do not accept a description of primary storage, such as RAM or ROM.

Do not accept capacity.

Do not accept an example device on its own (e.g. hard disk drive).

Example answers and how they were marked
Full marks2/2

Secondary storage is non-volatile, so it does not lose data when the power is turned off. It is used to store programs and data files for later use.

Why: Non-volatile / keeps data when the power is off (1) and used to store programs and data files (1), each idea clearly stated.

Some marks1/2

Secondary storage is used to store programs and data files.

Why: Stores programs and data/files (1), but nothing is said about it being non-volatile or not directly accessible by the CPU.

No marks0/2

Secondary storage is volatile memory that holds the data the CPU is using at the moment.

Why: Describes primary storage (RAM) and says it is volatile, which the mark scheme says not to accept, so no marks are awarded.

3Describe2 marksStored Program Computers Swap Remove

A computer is based on the von Neumann stored program concept.

Describe how the CPU uses main memory (RAM) during the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • The program's instructions (and the data it uses) are held in main memory/RAM (1) so the CPU fetches both the instructions and the data from that one memory (1)
  • The CPU fetches the next instruction from main memory/RAM (1) using the address of the memory location that holds it (1)
  • The CPU reads/fetches data from main memory/RAM (1) when an instruction needs it and writes the result back to main memory/RAM (1)
  • The program's instructions are held in main memory/RAM while the program runs (1) and the CPU fetches them one at a time/one after another to be decoded and executed (1)

Allow 'memory' for main memory/RAM.

Allow 'gets' for fetches/reads.

For both marks, the development must say what the CPU does with the contents of main memory (fetches/reads/writes), not just that main memory is used.

Do not accept answers about the program being stored in secondary storage, such as on a hard drive, or about it being loaded from there.

Do not accept benefits such as the computer running faster or being easier for the user.

Do not accept naming CPU components (control unit, arithmetic logic unit, registers) or buses on their own, without saying what is stored or fetched.

Do not accept 'the computer stores data' on its own, without a link to the instructions of a program.

Example answers and how they were marked
Full marks2/2

The program's instructions and the data it uses are both held in the same main memory (RAM), so the CPU can fetch the instructions and the data it needs from that one memory.

Why: Linked point (1) that instructions and data are stored together in main memory, with the development (1) that the CPU fetches both from the same memory.

Some marks1/2

The CPU fetches the instructions from main memory so that they are processed more quickly.

Why: The first point earns (1) for the CPU fetching instructions from main memory. The second statement is a benefit (speed), which the 'Do not accept benefits' line rules out, so it earns nothing.

No marks0/2

The control unit decodes each instruction and the ALU carries out the calculations.

Why: Both statements name CPU components without saying what is stored, fetched or written, which the mark scheme tells examiners not to accept, so neither earns a mark.

4Describe2 marksEmbedded Systems Swap Remove

A drone is controlled by an embedded system.

Describe the purpose of the embedded system in the drone.

[2 marks]
Mark scheme

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

  • It controls the motors/rotors (1) so that the drone can take off, hover, turn and land (1)
  • It keeps the drone stable/level automatically (1) by taking readings from a sensor (accelerometer/gyroscope/GPS) (1)
  • It receives signals from the remote control (1) and changes the speed of the motors to steer the drone (1)
  • It monitors the battery level (1) and brings the drone back to the ground before the battery runs out (1)

The development must relate to the function given in the point.

Accept a named function that the embedded system controls, e.g. 'it keeps the drone level', as the first mark (1).

Award the second mark only when the development gives a specific outcome or detail of that function, e.g. 'so that the drone can take off, hover, turn and land' or 'by changing the motor speeds to keep it level'.

Do not award the second mark for a generic outcome such as 'so it works', 'so it can fly' or 'so the drone moves'.

A bare 'it controls the motors so it can fly' therefore earns the first mark only.

Allow any other specific function of a drone that is carried out by the embedded system.

Do not accept 'it flies the drone' / 'it is the drone's brain' / 'it makes the drone work' without a named function being controlled.

Do not accept answers that describe the user or the remote control flying the drone with no function carried out by the embedded system.

Example answers and how they were marked
Full marks2/2

It keeps the drone level while it is in the air by reading the accelerometer and changing the speed of the motors.

Why: Named function of the embedded system, keeping the drone level (1), developed with the sensor reading and motor speed changes that achieve it (1).

Some marks1/2

It controls the motors of the drone.

Why: First mark only (1) for naming a function the embedded system controls, with no linked outcome or detail to earn the second mark.

No marks0/2

It is the brain of the drone and makes the drone work.

Why: Vague phrase with no named function being controlled, which the mark scheme's 'Do not accept' line rules out.

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