5.5 plant responses Flashcards
2 things plants respond to
- abiotic stress
- herbivory
herbivory responses
CHEMICAL
- releasing pheromones and alkaloids
PHYSICAL
- folding in response to touch
tropism
plant growth response to a stimulus
shoots phototropism
positive
roots phototropism
negative
bury deeper into soil, anchor plant, absorb more water for photosynthesis
where is auzin produced
parts of plant actively dividing; TIP OF shoots and roots
- MOVES BY DIFFUSION
auxin in shoots
promote cell elongation
auxin in roots
inhibit cell elongation
gibberellins
-seed germination (activates genes for amylase and protease and breaks down food stors)
- flowering
- stem elongation (stiulates cell division and elongation)
ABA
- INHIBITS seed germination and bud growth
- invovled in sotmatal closure when low water stress
ethene
promotes fruit ripening
auxins
- promote cell elongation
- inhibit lateral bud growth
- INHIBIT LEAF ABSCISSION
4 difference in hormones anials vs plants
-plant hormones not produced in endocrine gland, [roduced in tissues
- p;lant hormones dont travel in blood, travel in x/p/diffuse
- plant act less rapidly
- animals act more specific tagret tissues , plants on most tissues
apical dominance
inhibition of growth of lateral buds further down the shoot, caused by chemicals prodiuced by the apical bud at the tip
cytokinins
promote bud growth , overcome apical dominance
how does auzin work?
- auxin promotes AT of H+ by an ATPase enzyme in plasma membrane into the cell wall
- low pH in cell wall is optimum for EXPANSINS to work. they break bonds within cellulose(and the H+ also disrupt cellulose) , cell wall LOOSENING, so that walls can expand
abscission
auxins INHIBIT
ethene promote
how do stomata open and close
- ABA binds to receptors on pm of guard cell
- causes Ca2+ ion channels to open, flow IN
- cause K+ channels to open, flow out
- water potenital inside cell increases, so water moves out by osmosis. flaccid cellsd
auxins commercially
- rooting powders
- HERBICIDES: stem elongation so quick that the plant cant make enough energy so its dies
2 similarities hormones plants and animals
- bind to receptors on target cell
- timulate enzyme cascade (secondary messenger)
Explain why plants are more able to form natural reproductive clones than animals (2)
- plants have mersitem tissue
- whereas most animal cells are already differentiated
Suggest three ways that farmers can maximise the efficiency of the transfer of energy up
food chains from primary consumers to humans
- keep animals warm
- reduce animal movement
- vaccinate animals
ecology is
the study of the interaction between organisms and their environment
4 marks describe hat happens when u remove the tip of a shoot?
- less auxin
- apical dominance overcome
- grwoth of lateral buds
- bushier plant
deciduous plant
loses leaves seasonally
3 commerical uses
- rooting powder
- seedless fruit
- control ripening
- weed killer
what does cAMP do
- activates proteins
- by phosphorylating
Explain why dwarfism can be described as a genetic condition.
- allele for sqarfism
- is inherited
scientist initally thought auxins were …. by light
destroyed
which 2 hormones are invovled in leaf senescene (dropping)
- auxin
- ethene
auxin and ethene interaction for abscission
- auxin inhibits ethene
- ethene promotes abscission
high auxin conc on roots
prevents growth of roots
