6 Flashcards
What is the definition of STIMULUS?
Detectable change in the internal/external environment of an organism that leads to a response
Stimuli can be physical, chemical, or biological changes that affect an organism.
What role does a RECEPTOR play in the response process?
Detects stimulus, specific to one type of stimulus
Receptors can include sensory organs or specialized cells.
What is the function of a COORDINATOR in response to stimuli?
Formulates a suitable response to a stimulus, e.g., nervous system / hormonal system
Coordinators integrate information from receptors and decide on the appropriate response.
What does an EFFECTOR do?
Produces response to a stimulus, e.g., muscles / glands
Effectors carry out the commands given by the coordinator.
Define RESPONSE in the context of organism behavior.
This response may be at the molecular level or involve the behaviour of a whole organism
Responses can range from cellular reactions to complex behaviors.
True or False: Organisms that respond effectively to their environment have a lower chance of survival.
False
Effective responses to environmental changes increase survival and reproductive success.
Fill in the blank: There is always a selection pressure favouring organisms with more appropriate _______.
[responses]
Appropriate responses enhance an organism’s chances of survival and reproduction.
What is the relationship between survival and passing alleles to the next generation?
Those organisms that survive have a greater chance of raising offspring and of passing their alleles to the next generation
This process is fundamental to natural selection.
What is taxis?
A taxis is a simple, directional response determined by the direction of the stimulus.
Used by simple mobile organisms who move towards or away from a stimulus.
What is positive taxis?
Positive taxis is the movement towards a favourable stimulus.
Example: Positive phototaxis – Single-celled algae will move towards light.
What is negative taxis?
Negative taxis is the movement away from an unfavourable stimulus.
Example: Negative phototaxis – Earthworms will move away from light.
What is positive phototaxis?
Positive phototaxis is when organisms move towards light.
Example: Single-celled algae move towards light to manufacture their food.
What is negative phototaxis?
Negative phototaxis is when organisms move away from light.
Example: Earthworms move away from light to conserve water and avoid predators.
What is positive chemotaxis?
Positive chemotaxis is when organisms move towards a region of higher concentration of a substance.
Example: Some species of bacteria move towards regions with higher glucose concentration.
