14.1 — stimuli and responses Flashcards
through what do organisms detect stimuli?
receptors
what do receptors do?
they initiate responses from effectors
what is the pathway of response in an organism?
- stimulus — a detectable change in the internal or external enviroment of an organism
- receptor — detects specific types of stimulus
- coordinator — coordinates a suitable response to the stimulus
- effector — produces a response to a stimulus
- response — the action produced by the effector
what is a stimulus?
a detectable change in the internal or external enviroment of an organism
what does a receptor do?
detects specific types of stimulus
what does a coordinator do?
coordinates a suitable response to the stimulus
what does a effector do?
produces a response to a stimulus
what is a response?
the action produced by the effector
why are responses to stimuli crucial for survival — what do they allow organisms to do?
they allow organisms to:
- navigate towards beneficial resources like food
- evade predators or harmful conditions
what does responses to stimuli do to the probability of survival and successful reproduction?
increases it
what is a taxis?
a taxis is a simple response whose direction is determined by the direction of the stimulus
what do taxes do?
they guide organisms either towards a beneficial stimulus or away from a harmful one
what do positive taxes do?
lead towards a favourable stimuli
what do negative taxes do?
prompt movement away from adverse stimuli
what are the some examples of taxes?
- positive phototaxes — when an organism moves towards light (e.g. when algae moves towards light for photosynthesis to synthesis food)
- negative phototaxis — when an organism moves away from light (e.g. earthworms move away from light because the heat of the sun can dry out their skin out)
- positive chemotaxis — when an organism moves towards a towards a region where a specific chemical is more concentrated (e.g. bacteria move towards regions rich in glucose to obtain food)
