1A Answer (AO1)
C Unsigned integers store more positive values
The only correct answer is C
A is not correct because unsigned integers are not more accurate
B is not correct because overflow errors can still occur with unsigned integers
D is not correct because the use of a parity bit is not relevant to the scenario.
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The only correct answer is C
A is not correct because unsigned integers are not more accurate
B is not correct because overflow errors can still occur with unsigned integers
D is not correct because the use of a parity bit is not relevant to the scenario.
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1B answer (AO2)
Award one mark for sight of either 1024 to the power of 4 OR x4
Award both marks for a correct expression including 10244 AND x4 (with nothing else)
e.g. 1024 to the power of 4 x 4
Accept for 10244 any equivalent showing understanding that 1 terabyte is 240 bytes
e.g.
● 1024 x 1024 x 1024 x 1024 (bytes)
● 2 to the power of 10 x 2 to the power of 10 x 2 to the power of 10 x 2 to the power of 10 (bytes)
● 1,099,511,627,776 (bytes)
Award both marks for 4,398,046,511,104 (bytes).
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Award both marks for a correct expression including 10244 AND x4 (with nothing else)
e.g. 1024 to the power of 4 x 4
Accept for 10244 any equivalent showing understanding that 1 terabyte is 240 bytes
e.g.
● 1024 x 1024 x 1024 x 1024 (bytes)
● 2 to the power of 10 x 2 to the power of 10 x 2 to the power of 10 x 2 to the power of 10 (bytes)
● 1,099,511,627,776 (bytes)
Award both marks for 4,398,046,511,104 (bytes).
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1C answer (AO2)
Award both marks for.
● P AND (T OR S)
● (P AND T) OR (P AND S)
Award one mark for:
● (P AND T) OR S
● P AND T OR S
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● P AND (T OR S)
● (P AND T) OR (P AND S)
Award one mark for:
● (P AND T) OR S
● P AND T OR S
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1D answer (AO1)
One from :
● 68
● 82 – 14
● R – D
● 18 – 4
Plus
● 0100 0100
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● 68
● 82 – 14
● R – D
● 18 – 4
Plus
● 0100 0100
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1e answer (AO1)
To prevent unauthorised reading/use/analysis/understanding (1)
of sensitive/payment/personal/customer data (1)
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of sensitive/payment/personal/customer data (1)
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2a answer (AO2)
A linked description such as:
A record for each guest (1)
that uses attributes for guest characteristics (1)
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A record for each guest (1)
that uses attributes for guest characteristics (1)
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2b answer (AO1)
WAN / Wide Area Network
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2c answer (AO2)
Indicative content:
● Cost - can be cheaper than hardware / can cost a lot for large amounts of data
● Space - likely to get more than on physical drives
● Scalability
● Trust / Control
● Physical security
● Access (read/write) speeds and impact on uses/applications
● Shared storage vs dedicated
● Often belongs to a third party
● Bandwidth limitation
● Data vulnerability due to unknown provider
● Access from any Internet devices
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● Cost - can be cheaper than hardware / can cost a lot for large amounts of data
● Space - likely to get more than on physical drives
● Scalability
● Trust / Control
● Physical security
● Access (read/write) speeds and impact on uses/applications
● Shared storage vs dedicated
● Often belongs to a third party
● Bandwidth limitation
● Data vulnerability due to unknown provider
● Access from any Internet devices
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2d answer (AO1)
B – TCP/IP
The only correct answer is B
A is not correct because HTML is not a protocol
C is not correct because an ISP is not a protocol
D is not correct because a URL is not a protocol
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The only correct answer is B
A is not correct because HTML is not a protocol
C is not correct because an ISP is not a protocol
D is not correct because a URL is not a protocol
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2e answer (AO1)
A description to include two from:
● each node/device is connected to multiple other nodes/devices
● it is decentralised
● ensures data can still be routed to the destination address if one node fails
● self-configuring
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● each node/device is connected to multiple other nodes/devices
● it is decentralised
● ensures data can still be routed to the destination address if one node fails
● self-configuring
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3a answer (AO1)
A description to include three from:
● NAND (memory)
● If a row/column/set of transistors conduct current / are open/charged, then this represents a 1
● If row/column/set transistors do not conduct current / are closed/uncharged, then this represents a 0
● Arranged in a grid (columns/rows)
● At row/column intersections, two transistors (control gate and floating gate) create a ‘cell’
● By applying voltage to the control gate transistors
● Electrons flow onto the floating gate
● Creates a net positive charge that interrupts current flow
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● NAND (memory)
● If a row/column/set of transistors conduct current / are open/charged, then this represents a 1
● If row/column/set transistors do not conduct current / are closed/uncharged, then this represents a 0
● Arranged in a grid (columns/rows)
● At row/column intersections, two transistors (control gate and floating gate) create a ‘cell’
● By applying voltage to the control gate transistors
● Electrons flow onto the floating gate
● Creates a net positive charge that interrupts current flow
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3B answer (AO1)
Any two from:
● Repairing files
● Compression
● Defragmentation
● Back up
● Anti-virus / anti-spyware / anti-malware
● Firewall
● Managing application updates
● Format disks/drives
● System analysis tools
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● Repairing files
● Compression
● Defragmentation
● Back up
● Anti-virus / anti-spyware / anti-malware
● Firewall
● Managing application updates
● Format disks/drives
● System analysis tools
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3c answer (AO2)
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4A answer (AO1)
4ai answer (AO2)
X axis correctly labelled (1)
Y axis correctly labelled (1)
Sample frequency indicated (1)
Do not award marks if wavelength is labelled, rather than sample frequency.
Accept for sample frequency if two points given that are shorter than the wavelength.
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Y axis correctly labelled (1)
Sample frequency indicated (1)
Do not award marks if wavelength is labelled, rather than sample frequency.
Accept for sample frequency if two points given that are shorter than the wavelength.
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4aii answer (AO1)
The amplitude / original sound can be represented more accurately.
Accept:
● Better (sound) quality
● Higher fidelity
● Clearer (sound)
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Accept:
● Better (sound) quality
● Higher fidelity
● Clearer (sound)
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4B answer (AO1)
B – RAM
The only correct answer is B
A is not correct because the ALU does not hold a program
C is not correct because a hard drive does not hold a currently executing program
D is not correct because the control unit does not hold a program
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The only correct answer is B
A is not correct because the ALU does not hold a program
C is not correct because a hard drive does not hold a currently executing program
D is not correct because the control unit does not hold a program
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4c answer (AO2)
Total number of bits to transfer:
1 mark for 20 × 10242
1 mark for × 8
Speed in bits per second:
1 mark for 2 × 1000000
Numerator/Denominator:
1 mark for:
𝑏𝑖𝑡𝑠 𝑡𝑜 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟
____________________
𝑏𝑖𝑡𝑠 𝑝𝑒𝑟 𝑠𝑒𝑐𝑜𝑛𝑑
e.g:
𝟐𝟎 ×𝟏𝟎𝟐𝟒 ×𝟏𝟎𝟐𝟒 ×𝟖
_______________________
𝟐 ×𝟏𝟎𝟎𝟎𝟎𝟎𝟎
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1 mark for 20 × 10242
1 mark for × 8
Speed in bits per second:
1 mark for 2 × 1000000
Numerator/Denominator:
1 mark for:
𝑏𝑖𝑡𝑠 𝑡𝑜 𝑡𝑟𝑎𝑛𝑠𝑓𝑒𝑟
____________________
𝑏𝑖𝑡𝑠 𝑝𝑒𝑟 𝑠𝑒𝑐𝑜𝑛𝑑
e.g:
𝟐𝟎 ×𝟏𝟎𝟐𝟒 ×𝟏𝟎𝟐𝟒 ×𝟖
_______________________
𝟐 ×𝟏𝟎𝟎𝟎𝟎𝟎𝟎
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4d answer (AO2)
A description such as:
● Input from sensor (1)
● The input level is compared against pre-set values (1)
● Output to LED/speaker (1)
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● Input from sensor (1)
● The input level is compared against pre-set values (1)
● Output to LED/speaker (1)
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4e answer (AO2)
A. Copper cable
B. Fibre optic
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B. Fibre optic
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5a answer (AO1)
1101 1000
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5b answer (AO2)
A description to include two from:
● (Cache) Stores regularly accessed instructions/data
● Reduces the need to access instructions/data from main memory
● Makes up for the difference in speed of the CPU and main memory
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● (Cache) Stores regularly accessed instructions/data
● Reduces the need to access instructions/data from main memory
● Makes up for the difference in speed of the CPU and main memory
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5c answer (AO2)
3D
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5cii answer (AO1)
Hexadecimal is used as a short-hand for binary / uses fewer digits/characters (1)
so humans make fewer mistakes / find it easier to read/understand/remember/manipulate (1).
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so humans make fewer mistakes / find it easier to read/understand/remember/manipulate (1).
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5d answer (AO1)
A description to include four from:
The control unit increments the program counter (1)
The control unit sends a signal (1) along the control bus (1)
…to the memory/MAR (to tell it to send) (1)
…(the address of) the memory location (holding the instruction) (1) ...which is loaded onto the address bus (1)
...(and carried to RAM to tell it to) load the instruction/ contents of the memory location onto the data bus (1) ...along which it is carried to the MDR/MBR. (1)
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The control unit increments the program counter (1)
The control unit sends a signal (1) along the control bus (1)
…to the memory/MAR (to tell it to send) (1)
…(the address of) the memory location (holding the instruction) (1) ...which is loaded onto the address bus (1)
...(and carried to RAM to tell it to) load the instruction/ contents of the memory location onto the data bus (1) ...along which it is carried to the MDR/MBR. (1)
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5e answer (AO1)
It is not sorted
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6a answer (AO2)
Award one mark for either:
Sight of: 1024 × 1024
OR
Sight of: divided by 64
Award both marks for correct expression, e.g.:
1024 × 1024
________________
64
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Sight of: 1024 × 1024
OR
Sight of: divided by 64
Award both marks for correct expression, e.g.:
1024 × 1024
________________
64
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6b answer (AO1)
A description such as:
The OS uses part of the secondary storage to act as part of main memory (1).
The OS moves programs that are not immediately needed out of main memory (1) and stores them in virtual memory / secondary storage (1) using paging (1)
Active programs are swapped into main memory (from virtual memory) (1).
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The OS uses part of the secondary storage to act as part of main memory (1).
The OS moves programs that are not immediately needed out of main memory (1) and stores them in virtual memory / secondary storage (1) using paging (1)
Active programs are swapped into main memory (from virtual memory) (1).
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6c answer (AO1)
Any one from:
● To check for bad programming practices
● To check for vulnerabilities in the programming language
● To check efficiency of code
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● To check for bad programming practices
● To check for vulnerabilities in the programming language
● To check efficiency of code
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6d answer (AO2)
A description such as:
Ransomware / malicious attachment/download (1)
encrypts the user’s files (1).
To get the key/decrypt the files (1) … ...(the user must pay a ransom to the code writers / remove the malware)
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Ransomware / malicious attachment/download (1)
encrypts the user’s files (1).
To get the key/decrypt the files (1) … ...(the user must pay a ransom to the code writers / remove the malware)
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7a answer (AO1)
A linked description to include two from:
● Reads the packet header
● Takes the recipient's address
● Compares the (recipient’s) address to the addresses of all devices that are connected to it (which are stored in the router’s routing table)
● Forwards the packet / network traffic to its destination
● Using the quickest/most efficient route.
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● Reads the packet header
● Takes the recipient's address
● Compares the (recipient’s) address to the addresses of all devices that are connected to it (which are stored in the router’s routing table)
● Forwards the packet / network traffic to its destination
● Using the quickest/most efficient route.
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7b answer (AO1)
An explanation such as:
Changes in requirements / technology (1) mean that security can be improved/compromised (1)
OR
Changes in law/regulations (1) mean that requirements/technology must change (1)
Do not accept statements about unauthorised access / security that do not refer to changes in requirements / technology etc.
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Changes in requirements / technology (1) mean that security can be improved/compromised (1)
OR
Changes in law/regulations (1) mean that requirements/technology must change (1)
Do not accept statements about unauthorised access / security that do not refer to changes in requirements / technology etc.
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7c answer (AO1)
A description such as:
Each packet has a sequence number (added at the sending end) (1)
The packets are put back into (sequence) order (at the destination) (1).
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Each packet has a sequence number (added at the sending end) (1)
The packets are put back into (sequence) order (at the destination) (1).
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7d answer (AO1)
A response to include two linked points, such as:
● Some children may not have devices / can afford devices (1), so the school might have to provide them (1)
● Some students will have more advanced devices (1), thereby having different learning opportunities (1)
● Screen readers / facilitating programs (1) improve access for students with disabilities (1)
● Access may not be appropriate (1) for students from some religions / cultures (1)
● Opens opportunities for access to experts (1) thereby providing for individual needs (1)
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● Some children may not have devices / can afford devices (1), so the school might have to provide them (1)
● Some students will have more advanced devices (1), thereby having different learning opportunities (1)
● Screen readers / facilitating programs (1) improve access for students with disabilities (1)
● Access may not be appropriate (1) for students from some religions / cultures (1)
● Opens opportunities for access to experts (1) thereby providing for individual needs (1)
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Assessment Objectives occurrences in this exam
AO1 = 20 (Demonstrate knowledge and understanding of the key concepts and principles of computer science)
AO2 = 13 (Apply knowledge and understanding of key concepts and principles of computer science)
AO3 = 0 (Analyse problems in computational terms:
●to make reasoned judgements
●to design, program, evaluate and refine solutions.)
AO2 = 13 (Apply knowledge and understanding of key concepts and principles of computer science)
AO3 = 0 (Analyse problems in computational terms:
●to make reasoned judgements
●to design, program, evaluate and refine solutions.)