7.3 (b) Gaseous exchange in plants Flashcards
Describe the mechanism of opening and closing of stomata based on POTASSIUM ION accumulation hypothesis.
What is the potassium ion accumulation hypothesis in relation to stomatal opening and closing?
The hypothesis proposes that potassium ions (K+) are actively transported into guard cells, leading to osmotic uptake of water and stomatal opening.
How do guard cells accumulate potassium ions (K+) during stomatal opening?
Potassium ions are actively transported into the guard cells by proton pumps located on the plasma membrane.
What triggers the opening of stomata according to the potassium ion accumulation hypothesis?
The uptake of potassium ions (K+) by guard cells causes an increase in osmotic potential, leading to water uptake and turgor pressure, resulting in stomatal opening.
Describe the role of potassium ions (K+) in stomatal closing.
During stomatal closing, potassium ions (K+) are actively pumped out of the guard cells, leading to a decrease in osmotic potential, water loss, and a decrease in turgor pressure, resulting in stomatal closure.
How does the potassium ion accumulation hypothesis explain the regulation of stomatal opening and closing in response to environmental cues?
Environmental cues such as light intensity, CO2 concentration, and water availability can modulate the activity of ion pumps in guard cells, leading to changes in potassium ion (K+) accumulation and subsequent stomatal movements.
What happens when stomata open?
When stomata open, it lets in water and makes the plant cells swell, which helps the plant take in carbon dioxide for photosynthesis.
How do plants close their stomata?
Plants close their stomata by pumping out potassium ions (K+), causing the guard cells to shrink and close the stomata.
What controls the opening and closing of stomata?
The opening and closing of stomata are controlled by factors like light, carbon dioxide levels, and water availability, which affect how many potassium ions (K+) are let in or pumped out.
Why is it important for plants to control their stomata?
It is important for plants to control their stomata because it helps them balance taking in carbon dioxide for photosynthesis and conserving water, especially in dry conditions.
What are the name of the special pumps responsible for bringing in potassium ions (K+) into the guard cells?
The special pumps responsible for bringing in potassium ions (K+) into the guard cells are called proton pumps. These pumps help the guard cells to swell and open the stomata.
How does the potassium ion accumulation hypothesis explain the regulation of stomatal opening and closing in response to environmental cues?
Environmental cues such as light intensity, CO2 concentration, and water availability can modulate the activity of ion pumps in guard cells, leading to changes in potassium ion (K+) accumulation and subsequent stomatal movements. For example, in bright sunlight, the high intensity of light triggers the activation of proton pumps in the guard cells. This increased activity of proton pumps results in more potassium ions (K+) being transported into the guard cells, leading to stomatal opening.
