3.1.3: Transport In Plants Flashcards
What happens to water vapour during transpiration?
Water vapour evaporates out of stomata on leaves, creating a lower pressure.
This loss in water volume is crucial for the movement of water up the xylem.
How does water move up the xylem?
Water is pulled up the xylem due to negative pressure created by transpiration.
This process is essential for the plant’s water transport system.
What property of water molecules contributes to the formation of a water column in the xylem?
Cohesion due to hydrogen bonds between water molecules.
This cohesion allows the water molecules to stick together, maintaining a continuous column.
What is the role of adhesion in water transport in plants?
Water molecules adhere to the walls of the xylem, helping to pull the water column upwards.
This adhesion works alongside cohesion to facilitate water movement.
What effect does the upward movement of water have on the xylem?
It creates tension, pulling the xylem in to become narrower.
This tension is a result of the negative pressure created during transpiration.
What are stomata?
Tiny pores mainly on leaves that facilitate gas exchange in dicotyledonous plants.
The opening and closing of stomata are controlled by guard cells.
What is the function of guard cells?
They control the opening and closing of stomata to prevent excessive water loss.
This mechanism is vital for maintaining water balance in plants.
What are xerophytes?
Plants with adaptations to reduce water loss, typically found in arid environments like deserts.
Examples include cacti and marram grass.
Describe an adaptation of marram grass that helps reduce water loss.
Leaves are rolled to trap transpired water vapour, creating a humid environment.
This adaptation reduces the water potential gradient and minimizes transpiration.
How do hair-like structures around stomata contribute to water retention?
They help trap humid air, reducing the water potential gradient.
This adaptation is particularly useful in xerophytic plants.
What is the significance of a thicker waxy cuticle in xerophytes?
It prevents water loss from the plant surface.
This is crucial for survival in dry environments.
What type of root system do xerophytes tend to have?
Extensive root networks to reach available water.
This adaptation allows them to access water sources that may be deep in the soil.
Fill in the blank: Stomata are controlled by _______.
guard cells
