plant hormones Flashcards
phototropism
a plant growth response to light
gravitropism
a plant growth response to gravity
are the roots / shoots negative / positive phototropic / gravitropic
shoots - positively phototropic, negatively gravitropic
roots - negatively phototropic, positively gravitropic
what is auxin and where does it work?
a plant hormone that controls growth near to tips of roots and shoots
where is auxin produced and where does it move and why?
produced in tips and moves backwards to stimulate cell elongation process
what happens if the tip of a shoot is removed?
no auxin is available so shoot may stop growing
what does extra auxin do?
growth in the shoot, but inhibits growth in the root
what happens when a shoot tip is exposed to light?
more auxin accumulates on the side that’s in the shade, so cells elongate faster on shaded side so shoot bends towards light
what happens when light falls evenly on the shoot?
auxin is evenly distributed and evenly travels down shoot, growth on all sides is even
what happens when a shoot is growing sideways?
shoots are negatively gravitropic - gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side, causing the lower side to grow faster, bending the shoot upwards as it promotes growth
what happens when a root is growing sideways?
roots are positively gravitropic- gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side, causing the lower cells to grow slower causing the root bend downwards towards gravity as it inhibits growth
where does auxin accumulate with gravity?
lower side
where does auxin accumulate with light?
shaded side
What happens to make a root grow in the direction of the force of gravity?
The top side grows more than the bottom side
What is positive phototropism?
Plants grow towards the light source
What effects do auxins have on plants?
Shoot cell growth and root cell inhibition
in shoots does auxin trigger/inhibit?
trigger
in roots does auxin trigger/inhibit?
inhibit
