transport in plants Flashcards
(23 cards)
what is a dicotyledonous plant?
plants with two seed leaves and a branching pattern of veins in the leaves
what is meristem?
a layer of diving cells
what is the phloem?
something that transports assimilates
what is vascular tissue?
consists of cells that are specialised for transporting fluids by mass flow
what is the xylem?
transports water and minerals
how is the xylem adapted to its function?
- dead cells form a continuous column
- tubes are narrow
how is the phloem adapted for its function?
-contains sieve tube elements –> make sieve plates
what are the three pathways that water can take?
- apoplast
- symplast
- vacuolar
what is the plasmodesmata?
gaps in the cell wall that contain cytoplasm
what is a potometer?
a device that can measure the rate of water uptake as a leafy stem transpires
what is transpiration?
- loss of water vapour
- mostly through stomata
what factors can effect transpiration?
- light intensity
- temp
- humidity
- air movement
- water availability
why is transpiration important?
- transports useful mineral ions up the plant
- maintains cell turgidity
- supplies water for growth, cell elongation and photosynthesis
- keep the plant cool
what is adhesion?
the attraction between water molecules and the walls of the xylem vessels
what is cohesion?
the attraction between water molecules caused by hydrogen bonds
what is the role of the endodermis?
-the Casparian strip blocks the apoplast pathway between the cortex and the medulla
what helps move the water up the stem?
- root pressure
- transpiration pull
- capillary action
what is a hydrophyte?
a plant adapted to living in water.
what is a xerophyte?
a plant adapted to living in dry conditions.
what are assimilates?
substances that have become part of the plant
what is a sink?
a part of the plant where assimilates are removed from the plant
what is the source?
a part of the plant which loads assimilates into the transport system
what are the 3 main stages of active loading?
1) H+ ions actively pumped out of the companion cell using ATP
2) high conc of H+ causes facilitated diffusion back into companion cell. Sucrose is carried passively with the H+
3) increased conc of sucrose in companion cell causes diffusion into the sieve tube element
