3.1.3: Transport In Plants Flashcards
What is the process of transporting organic substances in plants called?
Translocation
Translocation refers to the movement of nutrients, particularly sucrose, from the source (where they are produced) to the sink (where they are used or stored) in plants.
What creates a high concentration of sucrose at the site of production in plants?
Photosynthesis occurring in the chloroplasts of leaves
Photosynthesis produces organic substances, such as sucrose, increasing its concentration in the source cells.
How does sucrose move from the site of production into the companion cell?
Facilitated diffusion
Sucrose diffuses down its concentration gradient into the companion cell through facilitated diffusion.
What type of transport moves H+ ions from the companion cell into the cell wall spaces?
Active transport
Active transport requires energy to move H+ ions against their concentration gradient.
What occurs after H+ ions move down their concentration gradient into the sieve tube elements?
Co-transport of sucrose with H+ ions via protein co-transporters
This process allows sucrose to be transported into the sieve tube element alongside H+ ions.
What effect does an increase of sucrose in the sieve tube element have on water potential?
It lowers the water potential
Lower water potential causes water to enter the sieve tube elements from surrounding xylem vessels via osmosis.
What happens to the hydrostatic pressure in the sieve tube element when water enters?
It increases
Increased hydrostatic pressure forces the liquid towards the sink.
What is sucrose used for at the sink?
Respiration or stored as insoluble starch
Sucrose can be utilized for energy through respiration or converted into starch for storage.
What causes the water potential to decrease at the sink cell?
Active transport of more sucrose into the sink cell
This decrease in water potential leads to the osmosis of water from the sieve tube element into the sink cell.
What is the role of the xylem in the process of translocation?
Water moves back into the xylem by osmosis
Water returns to the xylem after being drawn into the sink cell, maintaining the balance of water movement.
What drives the movement of soluble organic substances in the sieve tube element?
Difference in hydrostatic pressure between the source and sink
The pressure gradient established by water and sucrose movement facilitates the transport of substances.
Fill in the blank: Water flows down the concentration gradient and into the phloem which increases _______.
water pressure
This increase in water pressure is essential for pushing the solution of sucrose towards the sink.
True or False: The removal of water from the sieve tube element increases hydrostatic pressure.
False
The removal of water decreases the volume in the sieve tube element, resulting in lower hydrostatic pressure.
