Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• It reads/monitors the temperature/humidity/light level using sensors (1) to switch the heaters/vents/lamps/watering system on or off when the reading is outside the set range (1)
• It compares the readings from the sensors with the set values/thresholds stored in its memory (1) to decide whether the conditions need to be changed (1)
• It monitors the light level using a light sensor (1) and turns the lamps on when the light falls below the level the plants need (1)
• It monitors the soil moisture using a soil moisture sensor (1) and turns the water pump/irrigation on when the soil is too dry (1)

For the second mark, the action/response must be linked to the sensor reading given in the first point.

Allow named sensors (temperature/humidity/light/soil moisture) and named outputs (heater, fan, vent/window, lamp, irrigation/water pump).

Do not accept answers that only name a sensor or only name an output, e.g. 'it has a temperature sensor and a heater', as there is no link between the reading and the control action.

Do not accept answers where a person switches the equipment on or off, as the embedded system controls the conditions automatically.

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

• Decodes instructions (1) to determine what action/operation is required (1)
• Sends control signals (1) along the control bus to coordinate/control the actions of other components (1)
• Controls the fetch stage (1) by causing the next instruction to be fetched from main memory/RAM (1)
• Controls the execute stage (1) by telling the ALU/other components when to carry out the required operation (1)

Do not accept responses relating to how the control unit affects performance, such as increasing clock speed.

Do not accept responses that describe the role of the ALU, registers or clock instead of the control unit.

Do not accept responses about the ALU performing calculations unless the control unit controlling the ALU is also stated.

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

• The read/write head moves over the surface of the platter (1) and detects whether each area of the disk is magnetised (1)
• The platter spins/rotates (1) so the read/write head can pass over the whole surface/tracks of the disk (1)
• The pattern of magnetised and non-magnetised areas detected by the read/write head (1) is read as binary 1s and 0s (1)
• The drive head detects the direction of magnetisation of each area (1) so the data can be read as binary (1)

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

Allow one mark for stating that data is read magnetically / that the read/write head detects the magnetisation of the disk without a linked reason.

Do not accept answers that describe how data is written to the disk, such as the head magnetising the platter, rather than how it is read.

Do not accept 'a laser reads the pits and lands' - this describes optical storage, not magnetic storage.