Select the correct answers to the questions from the given options. (Do not copy the questions, write the correct answer only.)
Which one of the following helps in the opening of stomata:
Topic: Potassium ions and stomatal opening
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Pick an option and check your answer. The full worked answer is below either way.
Answer
(b) Potassium ions.
POTASSIUM IONS (K⁺) drive the opening of stomata. They are pumped INTO the guard cells, which raises the solute concentration inside, so water enters by OSMOSIS. The guard cells become TURGID, and because their inner walls are thicker and less elastic they bow outwards — opening the pore.
When potassium moves out, the reverse happens: water leaves, the cells become flaccid, and the stoma closes.
This is the POTASSIUM ION THEORY of stomatal movement, and naming it shows you understand the mechanism rather than the fact.
Do not confuse this with MAGNESIUM, which is also important to leaves but for a different reason entirely — it is the central atom of the CHLOROPHYLL molecule. That is why option (c) is offered.
Potassium ions.