Transport In Plants Flashcards
Why is xylem made of dead cells
Smooth flow of water
Walls of xylem strengthened with
Lignin to prevent collapse of vessel
Sieve plates
Allow rapid flow if manufactured food substances through sieve tubes
Vascular bundles arranged in ring around central region called
Pith
What’s in between xylem and phloem
Tissue called Cambium
In between pith and epidermis
Cortex
Cortex function
Store up food substances
Source
Supplies food substances to other parts of plant
Sink
Stores food substances
How do root hairs absorb mineral ions
Active transport
Root hair cell adaptations
- long and narrow
- partially permeable
- many mitochondria to release energy for active transport
Transpiration
Loss of water vapor from the mesophyll cells through the stomata of the leaf
Functions of transpiration
- help water and mineral ions to move out of plant
- cool down plant with evaporation of water from cells in leaves (remove latent heat of vaporization)
Importance of transpiration
- draws water and mineral ions from root to stem and leaves
- remove latent heat of vaporization
- water transported to leaves can be used in photosynthesis to keep cells turgid and to replace water lost by cells
Factors affecting rate of transpiration
- wind
- light
- temperature
- humidity
Why does humidity slow down rate of transpiration
The higher the amount of water vapor in the air, the concentr gradient is decreased and diffusion is slowed thus decreasing rate of transpiration
How do plants wilt
In strong sunlight when the rate of transpiration exceeds the absorption of water by the roots, cells lose their turgor and become flaccid and wilt
Advantages of wilting
When the lead folds up, the surface area expose to sunlight is reduced. Excessive loss of water through evaporation causes the guard cells to become flaccid and stomata close
Rate of transpiration decrease
Disadvantages of wilting
Water becomes a limiting factor
When guard cells are closed, carbon dioxide cannot enter leaf and carbon dioxide will become limiting factor
Rate of photosynthesis is decreased
Transpiration pull
When evaporation of water from leaves removes water from xylem vessels and results in a suction force which pulls water up the xylem vessels. The suction force caused by transpiration is called transpiration pull
Transpiration stream
Stream of water up the plant
