Edexcel GCSE Computer Science (1CP2) exam questions

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Practice paper

6 questions · 18 marks

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1Multiple choice1 markCharacter Sets Swap Remove

ASCII is a character set used for representing text.

Identify the number of bits used to encode each character in ASCII.

[1 mark]

Mark scheme

B 7 (1)
The only correct answer is B. The correct answer is 7 bits.
A is not correct because 6 bits give only 64 different characters
C is not correct because 8 bits are used by extended ASCII to give 256 characters
D is not correct because 16 bits give 65 536 different characters, which is far more than the 128 in ASCII

Example answers and how they were marked

Full marks1/1

B 7

Why: B is the only correct answer: each ASCII character is encoded using 7 bits (1).

No marks0/1

C 8

Why: Near miss scoring 0: 8 bits is extended ASCII, and the scheme's C line says extended ASCII, not ASCII, is not the answer.

No marks0/1

A 6

Why: Misconception scoring 0: 6 bits give only 64 different characters, so it cannot be ASCII.

2Short recall1 markSecondary Memory Swap Remove

Data is stored on optical discs as pits and lands.

Name the component in an optical disc drive that reads this data.

[1 mark]

Mark scheme

Award one mark for:

Laser (1)

Allow laser beam

Do not accept read/write head

Do not accept pits

Do not accept lands

Do not accept reflective surface

Do not accept magnet/magnetic

Example answers and how they were marked

Full marks1/1

Laser

Why: Laser is the creditworthy answer (1).

No marks0/1

A read/write head

Why: Read/write head is not accepted by the mark scheme; it reads magnetic media, not optical discs, so no marks are awarded.

No marks0/1

Pits and lands

Why: Pits and lands are what the laser reads, not the component that reads the data, so the mark scheme does not accept them.

3Describe2 marksUtility Software Swap Remove

A student has a large number of photographs stored on a computer.

Describe the purpose of data compression software.

[2 marks]

Mark scheme

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

Makes a file/files smaller (1) so less storage space is needed on the disk (1)
Reduces the size of the data (1) so it takes less time to upload/download/transfer the file (1)
Compresses files/folders into a single file (1) so an attachment is under the size limit for email (1)
Reduces the size of the files (1) so more of them fit onto a storage device/backup media (1)

Do not accept 'it compresses the files' on its own, as this repeats the question.

Do not accept responses about protecting files from malware/viruses or about deleting files.

Example answers and how they were marked

Full marks2/2

It makes the files smaller (1) so that they use less storage space on the computer and more of them fit on the disk (1).

Why: The point (1) and a linked development giving the benefit (1).

Some marks1/2

It makes files smaller.

Why: This is the point (1) but there is no development of what the smaller size leads to, so only one mark.

No marks0/2

It protects the files from viruses so that they cannot be damaged.

Why: This describes anti-malware software, which the mark scheme does not accept; no creditworthy point is made.

4Calculate2 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.

5Discuss6 marksUser Management Swap Remove

A school library has 24 computers that are shared by students and teachers throughout the day. Each computer runs an operating system. The school wants users' work to be kept private and the computers to be used only by authorised people.

Discuss how the operating system's user management features can be used to share the computers securely.

Your answer should include:

user accounts
authentication
the benefits for the school.

[6 marks]

Mark scheme

Indicative content

User accounts

Each student and teacher should have their own user account, so the operating system can identify the person who is logged on.
The operating system keeps a record of all valid users on the computer, so unknown users are not allowed to log in.
A separate home area or folder can be created for each account, so a student's saved work is kept apart from other users' work.
An account can be disabled when a student leaves the school, so they can no longer access the computers.

Authentication

A username and password can be required at login, so only users with the correct details can use the computer.
The operating system checks the entered password against the stored password for that account before allowing access.
Users should be encouraged to choose a strong password, which makes it harder for someone else to guess and log in.
The operating system can lock an account after several failed login attempts, which reduces the chance of someone trying passwords repeatedly.

Benefits for the school

Many students can share the same computers because each person's files are kept separate.
Work is less likely to be deleted or changed by another student, because users only see their own files.
The school can see which account was used on a computer, so misuse can be traced to a user.
Teachers can be confident that only authorised people can use the library computers.
The school does not need a separate computer for every student, so it saves money.

Levels

Level 0 (0 marks): No rewardable content.
Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Level 3 responses must cover both user accounts and authentication, and apply them to the school library.

Do not accept general operating system functions such as file management or process management unless they are explicitly linked to managing users.

Example answers and how they were marked

Full marks6/6

Each student and teacher should have their own user account with a username and password. When someone logs in, the operating system checks the password against the one stored for that account, so only authorised people can use the computer. Each account can have its own home folder, so a student's work is kept private and another student cannot open or delete it. If a student leaves the school, their account can be disabled so they cannot log in again. This lets the school share a smaller number of computers safely, as each user's work stays separate and any misuse can be traced to the logged-in account.

Why: Level 3. It explains user accounts, authentication and benefits, with sustained links to sharing computers in the school library.

Some marks4/6

Every user should have a username and password. The operating system checks the password so that people who are not allowed cannot log in. Each user should also have their own area to save files so they do not delete other people's work.

Why: Level 2. Basic accounts and authentication points are made and linked, but the benefits to the school are only briefly applied and not developed.

No marks0/6

The operating system manages the users by looking after the files in folders and by making sure the printer works for everyone. It also keeps the computer running quickly when lots of students use it.

Why: Level 0. These are general operating system functions such as file management and peripheral management, not user management, so no creditworthy point is made.

6Discuss6 marksTranslators Swap Remove

A student is writing a program in a high-level language. The student runs the program after every small change to check that it works.

Discuss whether the student should use an interpreter or a compiler while writing and testing the program.

Your answer should include:

how each translator deals with a syntax error
how much of the program is translated at a time
how this affects the student's testing.

[6 marks]

Mark scheme

Indicative content

How each translator deals with a syntax error

An interpreter stops as soon as it finds a syntax error and displays an error message.
With an interpreter, the lines before the error have already been executed, so the student can see how far the program got before it stopped.
A compiler reports errors at the end of translation, so the student gets a list of all the syntax errors in the program in one go.

How much of the program is translated at a time

An interpreter translates one line at a time and executes each line immediately.
A compiler translates the whole program in one go before any of it is run.
A compiler produces object code, so after every change the whole program must be compiled again before the student can run it.
An interpreter produces no object code, so the student does not have to wait for the whole program to be translated before it runs.

How this affects the student's testing

An interpreter suits this student because the program can be run straight away after each small change.
The interpreter stops at the first error found, so the student fixes that error and runs the program again, but may only find the next error on the next run.
Reporting every error at the end of compilation means the student can fix several errors at once, but cannot run the program until the whole program compiles.
The student should use an interpreter while testing, and compile the finished program once it works.

Levels

Level 0 (0 marks): No rewardable content.
Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Level 3 responses must relate the way each translator works to the student's testing, not just describe the two translators.

Do not accept answers about run-time or logic errors where no comparison of the translators is made.

Example answers and how they were marked

Full marks6/6

The student should use an interpreter while testing. An interpreter translates one line at a time and executes each line straight away, so as soon as the student has made a small change the program can be run without waiting for the whole program to be translated. If there is a syntax error, the interpreter stops at that line and displays an error message, and the lines before it have already been executed, so the student knows exactly where the problem is. A compiler translates the whole program in one go and only reports the errors at the end, so the student would get a list of all the syntax errors, but could not run any of the program until the whole program compiled successfully.

Why: Explains how each translator deals with a syntax error, how much is translated at a time (one line executed immediately against the whole program at once) and links both to the student's testing, with a conclusion. Level 3.

Some marks4/6

An interpreter translates one line at a time and stops when it finds an error, so the student can see where the error is. A compiler translates the whole program and reports all the errors at the end. The interpreter is better for testing because the student can run the program straight away after a change.

Why: Adequate: correct points about error reporting and one line at a time, with a recommendation, but the effect on testing is only asserted rather than reasoned through, so the linkage is not sustained. Level 2.

Some marks1/6

The student should use a compiler because it translates the program one line at a time and stops at the first error, which makes testing quicker.

Why: The roles of the two translators are reversed, so the answer only makes a basic point about testing more quickly. Level 1.

Edexcel GCSE Computer Science (1CP2) Exam Questions

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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

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