Chapter 7- Transport In Plants Flashcards
Describe process of Apoplastic pathway
- Water enters the cell wall and moves through it
- water may move from cell wall to the next thorough the intercellular spaces
- water may move directly from cell wall to cell wall
The process of symplastic pathway
- Water enters cytoplasm by osmosis through partially permeable cell surface membrane
- water moves into the sap in the vacuole through tonoplast by osmosis
- water may move from cell to cell thorough plasmodesmata
- water may move from cell to cell through adjacent cell surface membrane
Why do sieve tube elements have little cytoplasm and no nucleus?
It provides more space for the sap to flow
Define transpiration
Loss of water vapor from plant, to its environment, by diffusion down a water potential gradient.
Define assimilate
Sugars (organic molecules) made by photosynthesis
What are the four factors that affect transpiration
- humidity
- wind speed
- temperature
- light intensity
Two function of transpiration
1- Cools the plant down
2-pumping water and minerals to the leaves for photosynthesis
How does wilting/becoming flaccid act as a defense mechanism in plants
Wilting reduces the surface area of leaves and stems exposed to the surrounding environment, therefore reducing transpiration
Disadvantage of transpiration
If transpiration is higher than the rate of water absorption, the cells will become flaccid and plant will start to wilt, to try to stop further loss of water.
What does the potometer do
It measures water uptake by the plant
Estimates transpiration rate
Define plasmodesmata
Gaps in cell walls that allow substances to diffuse through
Define translocation
Transport of soluble organic substances within a plant
Why is glucose produces in the leaves by photosynthesis converted to sucrose?
Glucose interferes with the water potential of cells.
Sucrose is less reactive than glucose
