mini test on response Flashcards
(45 cards)
define phototropism
directional response to light
what is auxin
a phytohormone (growth factor produced in response to light)
on what side of the plant does auxin accumulate
shady side
effect of auxin on plant shoots
causes cell elongation by breaking down the cell walls using H+ ions to increase acidity, weakens hydrogen bonds between molecules- water enters
the effect of a plant growth factor depends on
- conc. of growth factor
- stem or roots
- developmental stage of the plant
- species of plant
- other growth factors present (synergism or antagonism)
define photoreceptors
structures or pigments that are sensitive to light, often of a specific wavelength
define phototropins
a group of photoreceptors primarily responsible for triggering phototropisms
where is auxin made?
meristems and young leaves
effect of IAA on root growth (phototropism)
negative- redistributes to the shaded side of the root and inhibits root growth so the side with a lower concentration will grow faster and the root will bend away from the light
effect of IAA on root growth (geotropism)
positive- redistributes to the underside of the root and inhibits growth so the root will bend towards gravity
define stimulus
a detectable change in the internal/external environment
define receptor
a cell or organ that detects change in internal/external environment
- detects a specific stimulus and converts energy into a generator potential which can cause an action potential in the sensory neurone
define coordinator
connects information between the receptor and appropriate effector
define effector
a cell, tissue, organ, or system that carries out a response
define taxes and kineses (vague)
simple responses that can maintain a mobile organism in a favourable environment
what’s the difference between taxes and kineses
taxes is directional but kineses is moving more or less
what do you use to keep a section of a choice chamber dry
calcium chloride
purpose of the cell body of a neurone
contains the nucleus and organelles
purpose of the dendrites in a neurone
conducts impulses towards the cell body
purpose of the axon in a neurone
transmits impulses away from the cell body
define nerve
complex tissue containing a bundle of axons of many neurons with a protective covering
purpose of schwaan cells
produce multiple plasma membrane layers which wrap around the axon and dendron, causing it to become myelinated
importance of myelination
action potential can be generated at nodes of ranvier, allowing saltatory conduction to occur instead of generating an action potential along the whole length of the neurone
define transducer
something that converts energy from one form to another
