Survival and response/tropisms/kinases/IAA Flashcards
To survive, animals must be able to…
-obtain food
-avoid being eaten
-find favourable conditions to live
-reproduce
What are three examples of responses in animals and plants?
-tropisms
-taxes and kinases
-reflex arc
What are tropisms?
responsible to directional stimuli that can maintain the roots and shoots of flowering plants in a favourable environment
Where are plant growth factors made?
NOT in glands, in many tissues all over the plant
Explain the two types of tropisms
positive - towards the stimulus
negative - away from the stimulus
Name 3 types of tropisms
phototropism, geotropism, chemotropism
What are the 3 main effects of plant growth factors?
-cell division
-cell elongation
-cell differentiation
What are photoreceptors?
structures or pigments that are sensitive to light
What are phototropins?
a group of photoreceptors responsible for triggering phototropisms
What happens when light is present to a phototropin?
when light is present, changes in the phototropin molecules trigger a cascade of reactions in the cell, then auxin is redistributed
Where are auxins made?
-in the shoot
-in young leaves
What is an example of an auxin?
indoleacetic acid (IAA)
What happens in the roots and shoots with IAA?
in shoots - diffuses to the shaded side
in roots - gravity moves IAA to the lower side of the root
What does IAA do to the cells in high concentrations in the shoots and roots?
-in shoots -elongate the cells causing bending towards the light
-in roots -inhibits elongation causing root to bend downward
Why are growth factors that are used commercially usually synthetically produced?
-much cheaper
-more efficient
than extracting them from plants
What is a challenge of studying growth factors?
they are usually only present in small amounts
What is kinesis?
a non-directional response to a stimulus
Explain what a kinesis is?
-animals keep moving when they experience undesirable conditions
-the more unpleasant the conditions, the more rapid the movement
-less turns made in undesirable conditions
How would you describe the movement in kinesis?
random
Use the example of woodlice under rocks as an example of kinesis?
-under rocks is generally humid
-this habitat is protected against predators
-if put into light, rate of movement increases and turning decreases
-increases the chance of moving into favorable conditions
What is taxis?
a directional response to a stimulus
Describe the movement in taxis?
more advanced movements directly towards or away from the stimulus
