Transpiration and translocation Flashcards
What is transpiration?
Transpiration occurs as water evaporates out of the leaves through the stomata openings in by diffusion and in the form of water vapour.
This cycle repeats as water moves through the xylem vessels in a continuous transpiration stream.
What are the 4 factors that affect the rate of transpiration?
ー Light intensity
ー Temperature
ー Wind speed
ー Humidity
Describe how light intensity affects transpiration rate
As light intensity increases, more stomata opens for photosynthesis = more transpiration occurs.
however, there will be a point where all the stomata are open and the graph will plateau.
Describe how temperature affects transpiration rate
Higher temperature = more kinetic energy = faster particles.
Which increases the rate of evaporation and diffusion from the leaf. The graph is a constant straight line.
Describe how wind speed affects transpiration rate
As wind increases, it moves away water particles surrounding the leaf. Therefore, more water will evaporate out to replace that. Graph increases.
Describe how humidity affects transpiration rate
Humidity is a measure of how much water is in the air.
An increase humidity = more water in the air… hence a LOWER concentration gradient = transpiration slows down. Graph is a constant decreasing straight line.
What is translocation
the movement of materials in plants from the leaves to other parts of the plant, and occurs in the PHLOEM.
- They are transported from SOURCES to SINKS.
SOURCES: where plants produce their food using photosynthesis
SINKS: the site where the plant stores the produced food.
