Response to stimuli Flashcards
What are the responses to stimuli?
Taxes
Tropisms
Kineses
What is a stimulus
A detectable change in the external or internal environment of an organism.
What detects stimuli
Receptors
What does a coordinator do
Formulates a suitable response to a stimulus
Sequence of events of a response
Stimulus
Receptor
Coordinator
Effector
Response
What is a taxis
A simple response whose direction is determined by the direction of the stimulus in a motile organism.
What is a positive taxis
Response towards the stimulus
What is a negative taxis
Response away from the stimulus
What is the advantage of taxis
Helps organism move to favourable environment and away from harmful or negative stimuli.
Bacteria moves to an area of high glucose concentration. What type of response is this?
Positive chemotaxis
Earthworms move away from light. What type of response is this?
Negative phototaxis
What is kinesis
Where the organism changes the speed of movement and rate of change in direction when in a changing environment
When an organism is in a favourable environment, what happens to its speed and change in direction?
It decreases and slows down
What is tropism
The growth of a part of a plant in response to a directional stimulus.
Tropisms of a plant shoot
Positive phototropism
Negative gravitropism
