5B: Plant Vascular Tissues Flashcards
What is xylem tissue?
Tubes that transport water and minerals (potassium, nitrogen) in one direction FROM ROOTS TO LEAVES
What are some features of a xylem tube?
- No end walls between cells
- Thick wall stiffened with lignin (hard, waterproof, rigid material)
What is phloem tissue?
Tubes that transport sugars and other nutrients in both directions
What are some features of a phloem tube?
- Cells have end walls with perforations
What is a vascular bundle made of in a stem?
- Sclerenchyma
- Phloem
- Xylem
What does the cross section of a root look like?
X shape (xylem)
Phloem inside each part of X
This is called a stele.
What does the cross section of a leaf look like?
Xylem and phloem along
Phloem is on top of xylem
What do sclerenchyma fibres do?
Provided support for stem
Name some plants organs.
Stem, roots, leaves, fruit, flowers
What are the functions of the root system?
- Provide stability + support to plant
- Absorb water + minerals from soil
What four processes are associated with water movement in plants, and explain briefly?
- Adhesion (water sticking to walls of stem)
- Cohesion (water molecules sticking to each other because of polarity)
- Osmosis (movement of water pressure)
- Transpiration (negative pressure)
What happens as water evaporates out of the stomata?
More water gets pulled up by xylem vessels to replace lost water
What happens if guard cells are turgid or flaccid?
Turgid: Stoma open (release water)
Flaccid: Stoma closed (retain water)
What are the 3 purposes of transpiration?
- Regulates temperature
- Transports nutrients
- Maintain turgor pressure
- Provides water for photosynthesis
How does hot temperature affect transpiration?
Hot temperatures will cause transpiration to increase, but very hot temperatures will cause transpiration to decrease.
How do guard cells relate with photosynthesis?
When the plant needs carbon dioxide for photosynthesis, guard cells open stoma for gas exchange (and release oxygen)
What is source and sink movement?
Sugars produced in sources (leaves) are delivered to sinks (growing parts) via thephloemvia translocation
Sinks: roots, young shoots, developing seeds
What is transpiration?
Process of water movement through a plant and its evaporation from parts such as leaves, stems and flowers
Why is glucose transported to roots?
Transported to sites of active growth where sugars are needed to support new tissue growth
How does humidity affect transpiration?
As humidity increases, rate of transpiration decreases (easier for water to diffuse into dry air rather than saturated air)
How does temperature affect transpiration?
As temperature increases, rate of transpiration increases (because kinetic energy of molecules also increase, causing osmosis and evaporation to occur faster)
How does light intensity affect rate of transpiration?
As light intensity increases, rate of transpiration increases. Light causes stomata to open wider for greater entry of carbon dioxide for photosynthesis (greater diffusion of water)
How can plants regulate water balance?
- Opening and closing of stomata
- Less stomata on the underside of a leaf
- Thick waxy cuticle that retains water
