survival and response Flashcards
stimulus
change in organsims internal or external environment
why’s it important organisms can respond to stimuli
organisms increase chance of survival by responding to stimuli
tropism
growth of plant in response to directional stimulus
positive towards stimulus
negative away from stimulus
role of growth factors in flowering plants
Specific growth factors eg auxins eg IAA move via phloem or diffusion
from growing regions eg shoot or root tips where produced
to other tissues where they relegate growth in response to directional stimuli
how does IAA affect cells in roots and shoots
shoots, high conc IAA stimulates cell elongation
roots high conc IAA inhabits cell elongation
explain gravitropism in flowering plants
cells in tip of shoot or root produce IAA
IAA diffuse down shoot or root evenly initially
then IAA moves to lower side of root or shoot so conc increases
in shoots this stimulates cell elongation
in roots it inhibits cell elongation
so shoots bend away from gravity
roots bend towards gravity
phototropism
cells in tips of roots and shoots produce IAA
IAA diffuses down root or shoot evenly initially
IAA moves to shaded side of root or shoot so once increases
in shoots it stimulates cell elongation so they bend toward light
in roots this inhibits cell elongation so they bend away from light
taxes
tactic response
directional response
movement towards or away from stimulus
eg woodlice moving away from light to avoid predators
kineses
kinetic response
non directional response
speed of movement of rate of direction change
changes in response to a non directional stimulus
depends on intensity of stimulus
eg woodlice move faster in drier environments to increase their chance of moving to a area of high humidity so they dont dry out
protective effect of simple 3 neurone reflex
rapid - only 3 neurones
few synapses
autonomic so doesnt have to be learn
protects from harmful stimuli eg prevents damage to body tissues
Describe how the effect of an environmental variable on the movement of
an animal (eg. woodlice) can be investigated using a choice chamber
set up choice chamber to create Dif envi conditions
humidity - add drying agent to one side and damp filter to other side
or light - shine light one side and cover other half with black card
control other envi conditions
teaspoon - 12 animals on centre of mesh platform and cover with lid
after set time eg 10 min record no of animals in each section
repeat after gently moving woodlice back to centre
The woodlice were left for 15 minutes
before their movement was recorded
when investigating the effect of humidity.
Explain why.
time to establish humidity
for substance to absorb water
woodlice no longer affected by handling
so that behaviour typical of humidity
how to ensure animals are and ethical handling
safely - cover open wounds
wash hands with soap after to minimise risk of infection
handle carefully and return them back to their habitats
why’s a mesh platform used when investigating humidity
keeps woodlice safe distance away from drying agent
Describe how the effect of an environmental variable on the movement of
an animal (eg. maggots) can be investigated using a maze
mazes USED TO INVESTIGATE TURNING BEHAVIOUR in response to Dif envi conditions
change envi at one end of t shape eg add food source
place animal at stem of t
record whether animal turns towards or away from food source
repeat with large no of maggots
wipe clean maze between trials
repeat with food on other side of T
