3.6.1.1. survival and response Flashcards
what is a stimulus
a change in an organisms internal or external environment
why do organisms need to respond to stimuli
to increase their chances of survival
what is a tropism
growth of a plant in response to stimuli
Positive = towards stimuli
Negative = away from stimuli
what is the role of growth factors in plants
specific growth factors move from growing regions (where they are produced roots/shoots) to other tissues where they regulate growth in response to directional stimuli
How does IAA effects cells in roots and shoots?
in shoots, IAA stimulates cell elongation
in roots, IAA inhibits cell elongation
( shoots is more elongated word than roots bec it has more letters)
explain gravitropism in plants
1.) cells in shoot/ root produce IAA
2.) IAA diffuses down shoot/ root evenly
3.) IAA moves to lower side of root/shoot so conc there increases
4.)in shoots IAA stimulate elongation.
in roots IAA inhibits elongation
5.) so shoots bend away from gravity where roots bend towards
(pic)
Explain phototropism in plants
1.). Cells in tip/roots produce IAA
2.) IAA diffuses down evenly
3.) IAA moves to shaded side
4.)shoot cells elongate / root cells inhibited elongation
5.) shoots bend towards light / roots bend away
Describe Taxes
a simple response that keeps an organism in a favourable environment.
directional response
moves towards or away from a directional stimulus.
Describe kinesis.
simple response to keep an organism in a favourable environment
non directional
speed and rate of direction change
depending on intensity
Explain the effect of a simple reflex
- Rapid as only 3 neurones and few synapses, synaptic transmission is slow
- autonomic (no thinking)
3.)protects from harmful stimuli
RP10.) (mealworm one) explain why the same organism shouldnt be used more than once
reduce stress on organism
prevent chance of learned behaviours
RQ10.)(Mealworm one) explain why a clean petri dish should be used each time
animals may have left chemical / scents which could influence behaviours of others
RQ10)(Mealworm one) why should petri dish be left for some time before experiment begins?
time to establish humidity gradient
mealworms no longer affected by handling
so that behaviour is typical of that humidity
RQ10) how to ensure safe and ethical handling of animals
cover open wounds and wash hands with soap before and after handing to reduce infections
handle carefully and return to habitat asap
RQ10)( why is a mesh platform used when investigating effects of humidity
to keep animal a safe distance from drying agent
RQ10 which statistical test should be used and why
chi squared
as data is categorical and comparing frequencies to see if there is a significant difference between observed and expected frequencies.
