stomatal opening and closing Flashcards
What is each stoma enclosed by? What do they look like?
Each stoma is enclosed by a pair of kidney-shaped guard cells.
How do guard cells open and close?
The guard cells open and close the stoma by changing shape.
How do the guard cells curve when they absorb water?
The walls of the guard cells are especially thickened on the insides. This causes the cells to curve when they absorb water and swell.
What happens when water enters the guard cell by osmosis?
When water enters the guard cells by osmosis, they become swollen or turgid.
How are guard cells joined together?
The guard cells are joined at their tips.
When water enters the guard cells by osmosis, they become swollen or turgid. What then happens to the guard cells?
The increase in size of the guard cells causes them to buckle outwards. The gap between them (which is the stoma) increases in size.
What happens when guard cells lose water? (2)
When the guard cells lose water they shrink in size. This causes the gap between them (the stoma) to close.
Define cohesion
Cohesion is the sticking of similar molecules to each other.
Define adhesion
Adhesion occurs when different molecules stick together.
What low levels cause stomata to open?
Low levels of carbon dioxide cause the stomata to open.
Why does photosynthesis resume in the morning?
In the mornings photosynthesis resumes in the leaf because of increased levels of light intensity.
Why do levels of co2 decrease in a plant? What happens as a result of this?
The level of carbon dioxide falls because it is absorbed by the cells in the ground tissue. This results in the stomata opening
If a plant is placed into a dark chamber with no carbon dioxide present, what will happen to the stomata?
If a plant is placed into a dark chamber with no carbon dioxide present, the stomata will open.
If a plant is placed into a dark chamber with no carbon dioxide present, the stomata will open. What does this show/prove?
This shows that carbon dioxide levels (and not light) trigger stomatal opening.
High concentration of CO2→ ?
Low concentration of CO2→ ?
High concentration of CO2→ stomata close
Low concentration of CO2→ stomata open
