IB MYP Sciences: Key concepts in MYP Sciences – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – the IB holds copyright in its own papers. Use these alongside the official past papers available through your school or the IB store.

This practice set tests the key concepts of IB MYP Sciences – change, relationships and systems – and how they build statements of inquiry and inquiry questions. It follows the IB MYP Sciences guide (for use from September 2014/January 2015; published May 2014, updated May 2019), and suits MYP years 4 and 5 (there is no SL/HL split). MYP has no prescribed content list; schools design their own units, but the key concepts are prescribed for all of them.

Each question is labelled with the criterion it trains: A Knowing and understanding, B Inquiring and designing, C Processing and evaluating, D Reflecting on the impacts of science. Real MYP work is judged against criterion level descriptors (achievement levels 1–8), so the [1] points in the answers are a revision aid, not IB marks. All data in the questions are fictional.

Study first with the key concepts study guide and revision notes. Also useful: the course hub, the checklist and the criteria in practice questions.

Questions

1. (Criterion A)

(a) Name the three key concepts the IB guide gives for MYP sciences. [1] (b) Name two other key concepts the guide says can also be important in sciences. [2]

2. (Criterion A) Classify each change as reversible, irreversible or self-perpetuating, giving a reason for each.

(a) Frying an egg. [1] (b) Water vapour condensing on a cold window. [1] (c) A nuclear fission chain reaction. [1]

3. (Criterion A)

(a) Using the guide’s meaning, distinguish between an open system and a closed system. Give one example of each. [2] (b) Explain why scientists building a model often treat the system as closed. [2]

4. (Criterion C) A student times a pendulum’s swing (period, T) for four lengths (L).

L (m)	0.20	0.40	0.80	1.60
T (s)	0.90	1.27	1.79	2.54

(a) Describe the relationship between L and T. State whether T is directly proportional to L, using the data. [2] (b) Calculate T²/L for the first and last rows and comment on the result. [2] (c) Predict the period for a length of 3.20 m. [1]

5. (Criterion B) A student wants to investigate the relationship between the thickness of insulation around a beaker and how fast hot water in it cools.

(a) State the independent and dependent variables. [2] (b) Write a testable hypothesis with a scientific reason. [2] (c) State one variable to control and how to control it. [1]

6. (Criterion C) Marble chips (calcium carbonate) react with dilute hydrochloric acid, releasing carbon dioxide. The reaction is run twice, starting at a total mass of 152.40 g each time.

• Flask A, open to the air: final mass 151.08 g.
• Flask B, sealed with a bung: final mass 152.40 g.

(a) Calculate the mass lost from flask A as a percentage of its starting mass. Give your answer to 2 significant figures. [2] (b) Explain the difference between the two results using the key concept of systems. [2]

7. (Criterion A) Explain how form relates to function in each case.

(a) The alveoli in human lungs. [2] (b) The long, pointed nose of a high-speed train. [2]

8. (Criterion A) Classify each inquiry question as factual, conceptual or debatable.

(a) What is the boiling point of pure water at sea level? (b) How does the structure of a substance affect how it behaves? (c) Should genetically modified crops be grown where food is scarce? [3]

9. (Criteria A and D) A teacher plans a chemistry unit on fuels and combustion. The key concept is change, the related concepts are energy and consequences, and the global context is globalization and sustainability.

(a) Write a statement of inquiry for this unit. [2] (b) Write one conceptual and one debatable inquiry question that come from your statement. [2]

10. (Criterion C) A fictional bean seedling is measured as it grows.

Day	0	8
Height (mm)	15	63

(a) Calculate the mean growth rate in mm per day. [1] (b) Calculate the percentage increase in height. [2] (c) Describe one qualitative change you would expect to observe over the same eight days. [1]

11. (Criterion D) A fictional island, Kelmora, gets all its electricity from a diesel power station. Its council proposes replacing it with solar panels and a large battery store. Using the key concepts of change, relationships and systems, evaluate the proposal. Include at least one strength, one limitation and a conclusion. [8]

Answers

1. (a) Change, relationships and systems (all three needed). [1] (b) Any two from: development [1]; time, place and space [1]; creativity. [2] Examiner insight: “Energy” and “models” are related concepts, not key concepts, so naming them in (b) earns nothing however well you know them.

2. (a) Irreversible: the egg proteins change permanently and cannot return to their raw state. [1] (b) Reversible: the water can evaporate again if the window warms. [1] (c) Self-perpetuating: neutrons released by each fission split further nuclei, which release more neutrons. [1] Examiner insight: A classification with no reason is a bare guess; each point here needs the “because” to show understanding.

3. (a) A closed system has resources that are not removed or replaced, for example a sealed jar with a burning candle; [1] an open system has its resources renewed, for example a river or pond. [1] (b) Treating the system as closed fixes what can enter or leave, [1] so there are fewer variables and the model is simpler to build and test. [1] Examiner insight: An example that clearly breaks the definition, such as calling an aquarium with a filter pump “closed”, cancels the credit for the definition.

4. (a) As L increases, T increases. [1] T is not directly proportional to L: doubling L from 0.40 m to 0.80 m multiplies T by only about 1.4, not 2. [1] (b) 0.90² ÷ 0.20 = 4.05 s²/m; 2.54² ÷ 1.60 = 4.03 s²/m. [1] T²/L is roughly constant (about 4.0), so T² is proportional to L. [1] (c) T = √(4.03 × 3.20) = 3.59 s (accept 3.6 s). [1] Examiner insight: “Proportional” needs evidence from the numbers; saying “T goes up with L so they are proportional” loses the second point in (a).

5. (a) Independent: thickness of insulation; [1] dependent: rate of cooling (temperature fall in a fixed time). [1] (b) The thicker the insulation, the slower the water cools, [1] because thicker insulation reduces the rate of energy transfer to the surroundings. [1] (c) Starting temperature of the water, for example heat all water to 80 °C before timing. [1] Examiner insight: A controlled variable earns credit only with a way of controlling it; “keep it fair” names nothing.

6. (a) Mass lost = 152.40 − 151.08 = 1.32 g. [1] Percentage = 1.32 ÷ 152.40 × 100 = 0.87%. [1] (b) Flask A is an open system: the carbon dioxide gas escapes into the air, so mass is lost. [1] Flask B is closed: no matter leaves, so total mass stays the same. [1] Examiner insight: Stopping at 0.0087 (the fraction) without multiplying by 100 gives a different quantity and loses the accuracy point, even with the subtraction right.

7. (a) There are very many alveoli, giving a large surface area, [1] and their walls are one cell thick, giving a short diffusion distance, so gas exchange is fast. [1] (b) The streamlined nose lets air flow smoothly around the train, [1] which reduces air resistance, so less energy is needed at high speed. [1] Examiner insight: Each answer needs both halves: a feature alone (“thin walls”) or a function alone (“for gas exchange”) earns half at most.

8. (a) Factual. [1] (b) Conceptual. [1] (c) Debatable. [1] Examiner insight: Question (b) has no single look-up answer, yet it is not debatable either; it asks you to explain a pattern that transfers, which is the mark of a conceptual question.

9. (a) For example: “Changes that release energy can have consequences for the environment that are felt far beyond where the change happens.” Credit: uses change, energy and consequences; [1] links to sustainability and does not just name the topic. [1] (b) Conceptual, for example: “How does the energy released by a chemical change depend on the substances involved?” [1] Debatable, for example: “Should wealthy countries cut fossil fuel use faster than poorer ones?” [1] Examiner insight: A statement such as “Burning fuels releases carbon dioxide” is a topic fact; it does not transfer to other units and earns no credit.

10. (a) (63 − 15) ÷ 8 = 6.0 mm per day. [1] (b) Increase = 48 mm; [1] 48 ÷ 15 × 100 = 320%. [1] (c) For example: the first leaves unfold and turn green. [1] Examiner insight: In (b), percentage change uses the starting value as the base; dividing by 63 gives 76% and loses the accuracy point.

11. Indicative points:

• Change: switching sources changes the island’s energy system from burning fuel to transferring light energy into electrical energy. [1]
• Strength (change and consequences): solar panels release no carbon dioxide when generating, so emissions from electricity fall. [1]
• Strength (systems): the island no longer depends on imported diesel, an input from outside its system that can be delayed or rise in price. [1]
• Relationships: solar output depends on light intensity, so it varies with time of day, season and cloud cover. [1]
• Limitation (systems): at night, output is zero, so the battery store becomes a vital component; if it is too small, supply fails. [1]
• Limitation: making panels and batteries uses energy and raw materials, and batteries must be recycled or disposed of at the end of their life. [1]
• Weighing up: whether the plan works depends on matching battery capacity to night-time demand, and perhaps keeping the diesel station as a backup at first. [1]
• Conclusion: a reasoned judgement, for example that the proposal is sound if storage is sized for demand, with a phased change-over. [1] [8] Examiner insight: An answer that lists strengths and limitations but never weighs them into a judgement stays in the lower criterion D bands, however accurate the science.

Where marks are usually lost

• Naming related concepts (energy, models, evidence) when a key concept is asked for.
• Classifying a change as reversible or irreversible with no reason.
• Claiming proportionality without checking the numbers: doubling one variable must double the other.
• Using the final value as the base in a percentage change.
• Giving a form with no function, or a function with no form.
• Calling a system closed when matter clearly enters or leaves it.
• Writing a statement of inquiry that only restates the topic.
• Listing pros and cons in a criterion D answer without reaching a judgement.
• Controlled variables listed without a method of controlling them.

Next steps

• Key concepts revision notes
• Key concepts study guide
• Investigation skills and exam preparation
• IB MYP Sciences course hub
• Printable MYP Sciences checklist
• All free 10-minute diagnostics
• Book a free trial class

Official syllabus

These questions are aligned to the IB MYP Sciences guide (for use from September 2014/January 2015; published May 2014, updated May 2019), International Baccalaureate Organization. Your teacher will share the task-specific clarifications for any assessed work.