Chapter 27.4-Transport of carbohydrates Flashcards
What is the main difference between the xylem transport and phloem transport?
Xylem transports water from soil to leaves, phloem transports carbohydrates to wherever they are needed. From sources to sinks
What are sources?
sources are regions where carbohydrates are stored or produced
What are sinks?
any portion of plants where carbohydrates are needed to grow and refuel.
Why does phloem transport take place in cells containing cytoplasm?
- the cytoplasm contains a high percentage of sugars and carbohydrates
What is the structure of phloem transport in angiosperm plants?
- during cell development they lose most of the membranes in cells
- Smooth ER
- Mitochondria
- plasma membrane
- cell wall
- Sieve plate: they contain large pores of phloem sap to pass through
- sieve tubes
Why is the rates for phloem transport lower in plants that are not angiosperms?
they have much narrower phloem conduits and they dont have large defined pores on their sieve plates.
How does phloem transport sugars from source to sink?
- Turgor pressure in source phloem is high because water is drawn by osmosis as sugar concentration increases.
- The differences in pressure between source and sink allows for the phloem to move
- The turgor pressure in the sink gets low because water leaves to a less concentrated area as sugar exits
How does phloem tissues try to prevent turgor pressure damage?
when there is damaged due to high turgor pressure or insects attracted to phloem sac sealing mechanisms get activated that prevent sap from moving through plates
How is phloem essential to the care of roots?
phloem supplies carbohydrates to fungi and bacteria that have symbiotic associations to the plant. To the rhizosphere, which is the soil layer that surrounds active growing roots. Helps give roots nutrtients
