5.1 - Sensory reception Flashcards
What is a stimulus?
A detectable change in the internal or external environment of an organism that produces a detectable response in the organism.
What organisms does this type of selection pressure favour?
Ones that respond appropriately to stimuli.
What are receptors?
Cells or organs that detect stimuli.
What are effectors?
One or more cells, tissues, organs and/or systems that carry out a response.
What are the sequence of events from stimulus to response?
- ) Stimulus.
- ) Receptor.
- ) Coordinator.
- ) Effector.
- ) Response.
What is a taxis?
A simple response whose direction is determined by the direction of the stimulus. (It can be measured towards the stimulus - positive, or away from the stimulus - negative.)
What is photo/chemo -taxis?
A response whose direction is determined by the direction of the light/chemical.
What is a kinesis?
A form of response where a more unpleasant stimulus causes the organism to move more rapidly and change direction more often.
What are the benefits of Kineses?
They allow the organism to spend more time in favourable conditions than unfavourable ones, as the increased motility when they are in unfavourable conditions helps to bring them to favourable conditions more quickly.
What is a tropism?
A growth movement of part of a plant in response to a directional stimulus. (It can be measured towards the stimulus - positive, or away from the stimulus - negative.)
What is the benefit of taxis?
Enables an organism (or motile part of it) to move itself towards favourable stimuli or away from unfavourable ones.
What do photo/hydro/geo -tropism relate to?
The growth of a plant concerning light/water/the ground.
What is the benefit of negative phototropism, positive geotropism and positive hydrotropism in plant roots?
Negative phototropism and positive geotropism increase the probability the roots will grow into the soil. Positive hydrotropism increases the chance they will develop where there is moist water.
