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Questions and Answers
Plants require ______ gases to perform cellular respiration.
Plants require ______ gases to perform cellular respiration.
oxygen
The exchange of oxygen and carbon dioxide occurs through ______.
The exchange of oxygen and carbon dioxide occurs through ______.
stomata
Each ______ is guarded by a pair of guard cells.
Each ______ is guarded by a pair of guard cells.
stoma
The condition of guard cells depends on potassium ion ______ by the cells.
The condition of guard cells depends on potassium ion ______ by the cells.
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During daytime, photosynthesis in guard cells produces dissolved sugar called ______.
During daytime, photosynthesis in guard cells produces dissolved sugar called ______.
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The ______ of the guard cells increases when potassium ions enter them.
The ______ of the guard cells increases when potassium ions enter them.
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In the absence of light, sugar in guard cells converts into ______.
In the absence of light, sugar in guard cells converts into ______.
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The potassium ions ______ from the guard cells to close the stoma.
The potassium ions ______ from the guard cells to close the stoma.
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Study Notes
Gaseous Exchange in Plants
- Plants require oxygen for cellular respiration, like other organisms.
- Unlike animals, plants synthesize their own food through photosynthesis.
- Photosynthesis requires efficient gas exchange, including absorption of light.
- Gas exchange occurs through stomata.
Stomata
- Stomata are pores on the lower epidermis of leaves.
- Each stoma is controlled by a pair of guard cells that change shape to open or close the pore.
- Guard cells have chloroplasts for photosynthesis.
- Stomatal opening and closing depends on guard cell turgidity.
- Factors influencing turgidity include potassium ion (K+) uptake and sucrose concentration.
Stomatal Opening
- Potassium ions enter guard cells, increasing solute potential and lowering water potential.
- Water moves into guard cells via osmosis, making them turgid.
- Guard cell shape changes, curving outwards, opening the stoma.
- High sucrose concentration in guard cells during the day (photosynthesis) lowers water potential, drawing water to stomata and opening them.
Stomatal Closing
- Potassium ions leave guard cells, reducing solute potential and increasing water potential.
- Water moves out of guard cells via osmosis, making them flaccid.
- Guard cells revert to their original shape, closing the stoma.
- Low sucrose concentration in guard cells at night (no photosynthesis) increases water potential, causing water to leave guard cells and closing the stoma.
Water Deficiency
- Water deficiency in plants causes guard cells to become flaccid, closing stomata to conserve water.
- Sufficient water causes guard cells to become turgid, opening stomata for gas exchange.
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Description
This quiz covers the process of gaseous exchange in plants, focusing on the role of stomata and guard cells. Learn how potassium ions and sucrose concentration influence stomatal opening and closing, essential for photosynthesis and cellular respiration. Test your knowledge on plant biology and gas exchange mechanisms.
