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Date	May 2021	Marks available	6	Reference code	21M.1.SL.TZ0.1
Level	SL	Paper	1	Time zone	no time zone
Command term	Explain	Question number	1	Adapted from	N/A

Question

Automatic crop watering system

Since 1990, Bertha Ascayo has been the manager of El Pallar, a farm in Chacra Province, where fruit trees are grown. In recent years, the climate has become more unpredictable, and the farm has suffered from periods of drought. Bertha is aware that she now needs to manage the watering of her fruit trees more than she has had to in the past.

Bertha will need to make some improvements to the watering system by adding a rain sensor and use a computer program to automate the watering process. She has chosen a company that uses open-source software. The same company also installed the equipment for the watering of the trees.

By using this software, Bertha can program a different watering plan for each type of tree. This includes programming the days of the week, times of the day, and length of the water cycle for each type of tree to be watered. For example, orange trees will be watered on Mondays and Thursdays at 6am for 45 minutes and at 8pm for 30 minutes.

Identify three characteristics of open-source software.

[3]

a.i.

A computer program uses data provided by a rain sensor to decide whether to water the trees. Identify three ways how the algorithm may be represented.

[3]

a.ii.

Water is becoming increasingly scarce in Chacra Province, and the provincial government is concerned there will be a point when there is not enough water for all of the farms to water their crops or fruit trees.

To manage water for the watering of crops and fruit trees, the provincial government of Chacra Province intends to use computer modelling to calculate how much water each farm in the province will receive.

Explain three factors that will contribute to the accuracy of this computer model.

[6]

The farmers of Chacra Province are concerned about the provincial government using a computer model to determine the amount of water they will be allowed to use to water their fruit trees.

To what extent should the farmers of Chacra Province rely on their knowledge and experience, rather than the computer-based solution provided by the provincial government, to manage the watering of the fruit trees?

[8]

Markscheme

Answers may include:

Anyone can edit and adapt it.
It is community driven (i.e., people who use and adapt the software can support each other in developing the software).
Open-source code can be viewed and adapted.
It is license free, with free redistribution rights.

Award [1] for identifying each characteristic of open-source software up to a maximum of [3] marks.

a.i.

Answers may include:

Flow chart
Pseudocode
Natural language
Structured language

Award [1] for identifying each way the algorithm may be represented up to a maximum of [3] marks.

a.ii.

Answers may include:

Quality of data input
High-quality data will allow for a more accurate model to be developed, as this data will be more reliable / current water levels within each area must be accurate.

Frequency of readings taken
More frequent readings may be able to pick up more subtle changes in the patterns of rainfall to increase the accuracy of the model / taking daily readings and using them to create the model will be more accurate than using monthly readings.

Number of variables taken into account when developing the model
More variables will enable other, potentially less important, factors to be considered when developing the model / what crops are farmed in different areas in the province / the weather conditions in different areas of the province.

Number of assumptions that have been built into the model
If any of the assumptions are weak or false, the model will be inaccurate.

Quantity of data input
If the sample of data is larger, the resulting model will be more accurate / spans several years.

Award [1] for identifying a factor that will contribute to the accuracy of the model and [1] for explanation why that will contribute to the accuracy of the model up to maximum of [2] marks.

Award [1] for each example given and an additional [1] if the explanation contributes to the accuracy of the model up to a maximum of [2] marks.

Mark as [2] + [2] + [2].

Answers may include:

Knowledge and experience will:

allow the farmers to see more than water needs for a plant (sick leaves, buds falling, etc.) without needing to develop a model (judgement)
be able to include other factors that may arise from time to time, such as quality of the water (e.g., coming with mud), and adjust their watering accordingly (judgement)
be able to resolve potential issues that cannot be programmed into the computer or that would be outside the scope of a computational solution (intuition)
provide expertise that cannot be quantified / ensure that in a worst-case scenario some of the farmers will be able to grow crops/trees (intuition).

Use of the provincial model will:

allow water to be distributed evenly between the farmers on a needs basis rather than based on the opinions of one or two stronger characters (equity)
potentially have problems, as a scientific approach has limits (e.g., there may be variables that the model does not take into account) – accuracy, the decisions around the water requirements of the trees may be based as much on intuition as algorithms and models
potentially have biased model/algorithms influenced by politics, e.g., farmers may not have fully disclosed their data / government may favour certain groups or industries.

Use of the computer system will:

reduce the amount of time farmers need to spend visibly checking their fields (automation)
allow exact water usage to be measured and lead to potential efficiencies in its usage (accuracy)
provide quantitative data that could be used as a model for other farmers growing the same trees in similar locations.

In part (c) of this question it is expected there will be a balance between the terminology related to digital systems and the terminology related to social and ethical impacts.

Keywords: agriculture, ecosystems, algorithm, accuracy, reliability, model, modelling, judgement, automation, change, power, systems, ethics, values

Refer to SL/HL paper 1, part c markbands when awarding marks. These can be found under the "Your tests" tab > supplemental materials > Digital society markbands and guidance document.

Examiners report

[N/A]

a.i.

[N/A]

a.ii.

[N/A]

Syllabus sections

Topic 3: Content » 3.1 Data

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