Lesson 1 : sensory reception in simple organisms and plants Flashcards
stimulus
a detectable change in the internal or external environment
receptor
a cell or organ that detects change in the internal/external environment
coordinator
connects info between the receptor and the appropriate effector
effector
a cell/tissue/organ/system that carries out the response
response
a change brought about due to a stimulus
why do plants respond to stimulus?
to increase chances of survival
taxes
movement directly towards or away from the stimulus
kinesis
random movement depending on the stimulus
tropisms
growth movement response of a plant towards or away from a directional stimulus
positive response
towards the stimulus
negative response
away from the stimulus
why is kinesis different to taxes?
response is not directional e.g if the stimulus is more unpleasant the movement will be faster and more erratic
why is kinesis useful?
it aids survival because animals will find favourable conditions and stay there
what causes tropisms?
IAA
what type of tropism is shown in the shoots of leaves?
describe
positive phototropism
- high IAA stimulates the cells on the shaded side to elongate causing the shoot to bend towards light
