Flashcards in Transport In Plants Deck (14):
What is the transpiration rate affected by?
What must healthy plants do?
Balance water loss with water uptake
What do both xylem and phloem form?
Continuous systems in leaves, stems and roots
Relate xylem to its function
Xylem - transpiration - movement of water and minerals from the roots to the shoot and leaves
Relate phloem to its function
Phloem - translocation- movement of food substances (sugars) up and down stems to growing and storage tissues
Describe the structure of xylem vessels
Thick strengthened cellulose cell wall with a hollow lumen (dead cells)
Describe the structure of phloem
Columns of living cells
What is transpiration?
The evaporation and diffusion of water from inside leaves
Describe how transpiration causes water to be moved up xylem vessels
- water evaporates from the internal leaf cells through the stomata
- water passes by osmosis from the xylem vessels to leaf cells, which pulls the entire thread of water in that vessel upwards by a small amount
- water enters the xylem from root tissue to replace water which has moved upwards
- water enters root hair cells by osmosis to replace water which has entered the xylem
Explain how the structure of a leaf is adapted to reduce excessive water loss
- waxy cuticle
- small number of stomata on upper surface
What does transpiration provide plants with water for?
Movement of minerals
Explain how the cellular structure of a leaf is adapted to reduce water loss?
- changes in guard cell turgidity
Explain why transpiration is increased by:
- increase in light intensity
- increase in temperature
- increase in air movement
- decrease in humidity
- more light increase rate of photosynthesis so increases transpiration
- rate of photosynthesis increase as temperature increases so increases transpiration
- transpiration increase as the movement of air increases
- decreased humidity increases transpiration as there would be less water vapour in the air