Survival And Response- Paper 2 Flashcards
Define stimulus
A detectable change in environment. These can either be external or internal
What is an effector
It responds to stimulation by the never cells- a muscle, a gland, an organ and a cell
State the simple reaction pathway
Stimulus—-> receptor—> coordinator—> effector —> response
Why do organisms need to respond to changes in environment: increase survival and reproduction by
Avoiding harmful environments, competition and predators
Keep in favourable environment such as correct temperature and humidity
Grow towards or away from stimuli such as flowering plants
Dispersing to find new mates
Behaviour patterns
Instinctive behaviour is an innate response to stimuli
Innate behaviour is genetically determined and is not learned
Members of a species which inherit alleles for a particular behaviour will produce the same response to a particular stimulus
What is kinesis and give an example using wood lice
A behaviour pattern where an animal responds to a change in stimulus by increasing or decreasing activity. It is a change in the rate of movement and is random
Woodlice move around more when the humidity is low. The rate of movement is related to the intensity of the stimulus. The movement is random and not directional
What experiment can be used to investigate kinesis in an organism
Choice chamber- organism is released into the chamber and after a set amount of time, the position of woodlouse would be recorded. The pattern of movement of the organism can also be recorded and the speed at which it moves
What is taxes and give an example using earthworms
The directional movement of an organism either towards or away from a stimulus
Positive taxis- towards the stimulus
Negative taxis- away from stimulus
Earthworms move away from light which is negative phototaxis, they have more chance of survival as when move into soil they are more likely to find food, more likely to avoid predators and less likely to dehydrate
What is a reflect action and what is its purpose/ what can it allow the organism to do
An example of a behaviour in which a certain stimulus produces a specific short lived response
They may allow the organism to protect against damage to body tissues, help escape from predators,enable homeostatic control, find food, mates or suitable environmental conditions
What is the normal process and what happens instead when a reflex action is happening
Normal: stimulus, coordinator, effector
Reflex: sensory, relay, motor
Describe what is meant by the term taxis
Moves towards or away from directional stimulus
Describe what is meant by the term kinesis
Movement is random/non-directional or animal does not move towards a particular stimulus
Explain the advantages of simple reflex arcs
Rapid
Protect against damage to body tissue
Do not have to be learnt
Help escape from predators
Enable homeostatic control
What is positive trophism and give an example using plant growth
Growth towards a stimulus
Plant shoots grow towards the light as there is an increase chance of light falling on leaves and increase rate of photosynthesis
What is a negative tropism and give an example using plant growth
Growth away from stimulus- plant roots grow away from plants and instead grow into the soil where they are most likely to absorb water and mineral ions
