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All 15 Flashcards — Open and Closed Systems
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Question
What is an open system in ESS?
Answer
An open system exchanges both matter and energy with its surroundings across the system boundary.
💡 Hint
Say: matter AND energy exchanged.
Question
Open system: what crosses the boundary?
Answer
Both matter and energy cross the system boundary (enter and leave).
💡 Hint
Matter + energy.
Question
What is a closed system in ESS?
Answer
A closed system exchanges energy with its surroundings but does not exchange matter (matter stays inside and is recycled).
💡 Hint
Say: energy in/out; matter stays.
Question
Why is Earth considered a closed system?
Answer
Energy enters as sunlight and leaves as heat, but almost no matter enters or leaves Earth, so matter is recycled within the system.
💡 Hint
Mention sunlight + heat + recycled matter.
Question
Give one clear open system example used in IB exams.
Answer
A pond is an open system: sunlight and rain enter, while water (evaporation/runoff) and organisms/heat can leave.
💡 Hint
Use pond: list 1 input + 1 output.
Question
Closed system: what crosses the boundary?
Answer
Energy crosses the system boundary, but matter stays inside and is recycled.
💡 Hint
Energy yes; matter no.
Question
Give one example of a closed system often used in ESS.
Answer
Earth (at the global scale) is the classic closed system example because matter is retained but energy is exchanged.
💡 Hint
Best exam example: Earth.
Question
In an open system, what is the difference between matter and energy?
Answer
Matter is physical stuff with mass (water, nutrients, organisms). Energy is not physical stuff (sunlight, heat) that drives change.
💡 Hint
Matter = can trap it. Energy = cannot.
Question
Give one open system example and one closed system example.
Answer
Open: a pond (matter + energy exchange). Closed: Earth (energy exchange, matter retained).
💡 Hint
Use pond + Earth.
Question
State one input and one output for a forest as an open system.
Answer
Input: sunlight or rainfall or nutrients. Output: heat loss, oxygen release, runoff water, or organisms leaving.
💡 Hint
Always provide 1 in + 1 out.
Question
Why is “pond” a strong open-system example for IB exams?
Answer
Because you can clearly identify inputs (sunlight, rain, nutrients) and outputs (evaporation, runoff, organisms leaving), showing matter and energy exchange.
💡 Hint
List 1 input + 1 output.
Question
Are global biogeochemical cycles open or closed systems? Explain.
Answer
They are closed systems at the global scale because the matter (atoms) is recycled within Earth, while energy enters and leaves.
💡 Hint
Say: matter recycled; energy exchanged.
Question
In exam answers, what is the quickest way to justify “closed system”?
Answer
State what crosses the boundary: energy crosses (sunlight in, heat out) but matter does not cross (it stays and is recycled).
💡 Hint
Always answer: what enters/leaves.
Question
Why are open systems described as dynamic?
Answer
Because inputs and outputs happen continuously, so storages and conditions can change over time.
💡 Hint
Dynamic = changing over time.
Question
What is the top-mark phrasing for open vs closed systems?
Answer
Open: exchanges matter and energy. Closed: exchanges energy but not matter. Always state what enters and what leaves.
💡 Hint
Say: what crosses boundary.
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