6A Responses in Plants and Animals Flashcards
Define tropism
the response of a plant to a directional stimulus
Define directional stimulus
a stimulus coming from a particular direction
How to plants respond to stimuli
by regulating their growth
Define positive tropism
growth towards a stimulus
Define negative tropism
growth away from a stimulus
Define phototropism
growth of a plant in response to light
What part of a plant is positively phototropic
shoots, meaning they grow towards light
What part of a plant is negatively phototropic
roots, meaning they grow away from light
Define gravitropism
growth of a plant in response to gravity
What part of a plant is negatively gravitropic
shoots, meaning they grow upwards
What part of a plant is positively gravitropic
roots, meaning they grow downwards
How do plants respond to directional stimuli
by using specific growth factors
Where are growth factors produced
in the growing regions of the plant
What do auxins do
stimulate growth of shoots by cell elongation high concentrations inhibit growth in roots
What does indoleacetic acid do in phototropism
IAA moves to the more shaded parts of the shoots and roots causing uneven growth
What does indoleacetic acid do in gravitropism
IAA moves to the underside of the shoots and roots causing uneven growth
How is Indoleacetic acid moved
via diffusion and active transport over short distances and over long distances via the phloem
Where are auxins moved to
control tropisms
Define tactic responses
the organism moves towards or away from a directional stimulus
Define kinetic responses
the organisms movement is affected by a non directional stimulus
How to use choice chambers to investigate animal responses
by covering one half of the lid with black paper and adding woodlice to investigate the effect of light or adding a drying agent to one side of the choice chamber to investigate humidity
