Please enable JavaScript.
Coggle requires JavaScript to display documents.
15.4 Control and coordination in plants - Coggle Diagram
15.4 Control and coordination in plants
Electrical communication
Depolarisation is achieved by the outflow of Cl- ions rather than the inflow of Na+ ions
Repolarisation is achieved by the outflow of K+ ions just like in neurones
Action potentials travel through plasmodesmata lined by cell surface membrane
Plant action potentials last longer and travel more slowly
Venus flytraps
Deflection of sensory hair activates Ca2+ ion channels in cells at base of hair
Ca2+ ions flow in and generate receptor potential
If this happens twice within 20-35s, the trap closes
Continuous activation leads to Ca2+ ions activating gland cells, causing the exocytosis of vesicles containing digestive enzymes
Chemical communication
Plant hormones = plant growth regulators
Produced in a variety of tissues
Move either from cell to cell or via phloem/xylem
Auxin
Synthesised in meristems (growing root and shoot tips)
Controls cell elongation
Stimulates ATPase to pump H+ ions into cell wall
Cell wall is acidified, activating expansins
Expansins enable cell to absorb water and stretch
Gibberellin
Synthesised in most parts of plants
Promotes cell extension in stems by stimulating XET to break bonds within hemicellulose molecules, allowing cell wall expansion
Absorption of water at start of germination causes gibberellins to diffuse into aleurone layer and synthesise amylase
Amylase hydrolyses starch into maltose, which is converted into glucose and transported to embryo and provides energy source
Works by promoting destruction of inhibitory DELLA proteins that prevent transcription of mRNA coding for amylase
Abscisic acid (ABA)
Controls responses of plants to environmental stresses (such as water shortage)
Causes stomatal closure