Taxes and Kinesis Flashcards
What is a stimulus?
a detectable change in the environment
What are the cells that detect specific stimuli called?
receptors
Why is it important for organisms to respond to stimuli?
to increase likelihood of survival
(by moving towards favourable and away from harmful)
What do taxes and kinesis aim to do?
keep organisms within their favourable conditions within the environment
What is a taxes response?
a simple directional response where an organism will move away from an unfavourable stimulus or towards a favourable stimulus
Give an example of negative taxes
- earthworms moving away from light, to help them avoid dehydration, predation and locate food
- woodlice moving away from hot/dry conditions
Give an example of positive taxes
- bacteria moving towards chemicals that help them survive
- Euglena moving towards light
What is kinesis?
random, non-directional movement, usually when an organism changes the speed of movement and the rate it changes direction
What would happen when an organism moves from an area of beneficial stimuli to an area of harmful stimuli?
would increase the rate it changes direction
What would happen if an organism is surrounded by harmful stimuli?
rate of turning decreases so it moves in a straight line to find an area of favourable conditions
What is a response?
a reaction to a stimuli
What is the role of a coordinator?
receives information and formulates a response to a stimulus
Give 2 types of taxis response?
phototaxis, chemotaxis
What is the type of response in the following example?
bacteria moving away from waste products
negative chemotaxis
