Regulatory mechanisms in Plants Flashcards
In plants, what is the primary organ of photosynthesis?
Plant leaves
What is the purpose of pores in plants?
They allow CO2 in and O2 out (air movement for gas exchange)
What is another name of pores?
Stomata
What is the problem with stomata being open?
Allows water vapour to escape
What is the loss of water vapour called?
Transpiration
How do plants minimise water losses?
By using guard cells to open and close stomata at certain times of the day
What do stems in plants do?
Supports leaves and transports organic materials (sugars), ions and water between the root and the leaves
What is at the top of each stem?
Terminal bud
What is at the axis of each new leaf?
Axillary bud
Where does mitosis occur in plants?
The terminal bud and axillary bud
What is the definition of stomata?
The pores through which gas exchange occurs
Where is the stomata usually found?
The epidermis (outer most layer of plants) of the leaf
What does each stoma consist of?
Two elongated guard cells
What causes a change in the stomata being open or closed?
Change in turgor pressure of the guard cells
What is the status of the stoma when then guard cells are turgid?
Pores open
What is the status of the stoma when then guard cells are flaccid?
Pores closed
When are stomata usually open?
During the day
When are stomata usually closed?
During the night
What is the environment of a saguaro cactus?
Harsh desert
What are the skin adaptations of the saguaro cactus?
Skin is covered with a thick, wavy coating that is waterproof, thus reducing water loss via transpiration
Skin is covered with hard spines and flexible bristles, which defend the water stored inside
How do plants replace water losses through transpiration?
Transporting water from the roots to the leaves
What does the root system provide?
Huge surface area to take in water
What are the three forces water in plants is under in xylem tubes?
- A pulling force by transpiration in leaves
- A pushing force exerted by osmosis and entry of water into root hair cells
- Adhesion and cohesion forces of water molecules (work against gravity)
What is the transpiration stream?
A unbroken water of water travelling from roots to leaves in xylem tubes, generated by the three forces
How is osmosis involved in the process of transporting water?
The water from the soil osmoses into the roots, which starts the whole process. The root system creates a massive surface area in which the plants draw in essential ions and water. This high SA is created by root hairs, extensions of epidermal cells that are short lived
What allows the water to transport under tension?
The cohesive property of water and the structure of xylem vessels
What is a xylem vessel?
A long, hollow tube composed of xylem cells
What the features of xylem cells?
Dead at functional maturity.
No cellular components (cytoplasm, membranes, etc)/
What are the types of processes that create the flow of water along xylem vessels?
Passive processes
What is the difference in pressure between inside xylem vessels and the atmosphere?
The pressure inside xylem vessels is usually much lower than atmospheric pressure
What are the features of the walls of xylem vessels?
They are thickened and contain the polymer lignin, which strengthens the walls (so they can withstand very low pressures without collapsing inwards)
Are water molecules polar or non-polar?
Polar