14.1- Survival and response

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  • Created by: Megan2413
  • Created on: 05-11-17 20:03
What is a stimulus?
It is a detectable change in the internal or external environment of an organism.
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How can a stimlulus increase survival chances of an organism?
By causing a response to move away from harmful stimuli such as a predator hunting prey or extreme temperatures
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What are stimuli detected by?
Receptors
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Receptors are ........... to one type of stimulus
Specific
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What does a coordinator do?
It formulates a suitable response to the stimulus
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Can coordination be at both molecular level or involve whole organs?
Yes
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What is a response produced by?
En effector
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Can an effector be at both molecular level or involve whole organs and behaviour?
Yes
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What are two means of communication of an effector in multi-cellular organisms?
Hormonal communication and nervous system
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What is the general reflex arc?
Stimulus > Receptor > Coordinator > Effector > Response
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What is a Taxis?
A movement in response to a directional stimulus
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What organisms does a taxis involve?
Animals
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What does a positive and negative taxis involve?
A positive taxis is the movement towards a favourable stimulus and a negative taxis is the movement away from an unfavourable stimulus
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A single-celled algae moves towards light- is this positive or negative phototaxis and why?
Positive phototaxis as they are photosynthetic organisms that require light to manufacture their food
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Earthworms will move away from light- is this positive or negative taxis and why?
It is a negative phototaxis because it is moving away from the light which increases their chance of survival because it takes them into the soil away from predators and nearer food sources
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Some species of bacteria will move towards a region where glucose is more highly concentrated- is this positive or negative chemotaxis and why?
It is positive chemotaxis because it is moving towards a favourable stimulus
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What is the difference between phototaxis and chemotaxis?
Phototaxis is a response to light whereas chemotaxis is a response to chemicals
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What would a taxis in response to gravity be?
Geotaxis
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What is kinesis?
A change in speed or direction to a non-directional stimulus
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What type of organisms does kinesis involve?
Animals
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How does an organism respond with kinesis when crossing a border between a favourable and unfavourable environment and why?
It rate of changing direction increases because then it is more likely of a quick return to a favourable environment which increases survival chances
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If an organism is well into an unfavourable environment, how may it respond with kinesis and why?
The rate at which is changes direction may slow down to ensure it moves in a long straight line and then turn quickly to get into a new favourable environment
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The response of a straight line movement- what type of stimulus does this apply to more?
A less directional stimulus which don't always produce a clear gradient from one extreme to the other
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When woodlice are in a favourable environment how would they respond?
They would move slowly and change direction less
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When woodlice are in an unfavourable environment how would they respond?
Quick movement and changing direction more to try and find another favourable environment
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What is a tropism?
It is the plant growth in response to a directional stimulus
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What is phototropism?
The plant growth response to light
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What is geotropism
The plant growth response to gravity
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How do plant shoots and roots respond differently to phototropism?
Shoots are positively phototropic as they move towards the light for photosynthesis whereas roots grow away from the light- negative phototropic
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How do plant shoots and roots respond differently to geotropism?
Shoots are negatively geotropic but roots are positively geotropic to better absorb minerals and water
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Other cards in this set

Card 2

Front

How can a stimlulus increase survival chances of an organism?

Back

By causing a response to move away from harmful stimuli such as a predator hunting prey or extreme temperatures

Card 3

Front

What are stimuli detected by?

Back

Preview of the front of card 3

Card 4

Front

Receptors are ........... to one type of stimulus

Back

Preview of the front of card 4

Card 5

Front

What does a coordinator do?

Back

Preview of the front of card 5
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