14.1&2 survival and response Flashcards
stimulus
a detectable change in the internal or external environment of an organism that leads to a response in the organism.
receptors
sepecific to one type of stimulus
effector
muscle
nervous system communication order
stimulus>receptor> coordinator>effector> response
taxis
simple response in which direction is determined by the direction of the stimulus
taxis example
earthworm
earthworm
will move away from light (negative phototaxis). this increases their chance of survival as it takes them into the soil where they are better all to conserve water
kinesis
a form of response in which the organism does not move towards or away from a stimulus and instead changes the speed at which it moves and the rate at which it changes direction
kinesis example
woodlice
woodlice
lose water from their bodies in dry conditions. when they move from a damp to dry area, they move more rapidly and change direction more often. this increases their chance of moving back into a damp area
tropisms
the growth of part of a plant in response to a directional stimulus.
plant shoots
grow towards light (positive phototropism) and away from gravity (negative gravitropism)
plant roots
grow away from light (negative phototropism) and towards gravity (positive gravitropism)
plant growth factors
affect the tissues that release hormones and influence plant growth
example of plant growth factor
indoleacetic acid (IAA)
