Biology Questions and Answers
negative. Positive phototropism is that
in which tgrowth) is towards the light sohe plant movement (orurce and (^)
negative phototropism is that in which
the movement (or growth) away from the light source.is inverse,
Phototropismexposition of one side of the plant to relates to auxins since t he
light makes these hormones
concentrate imakes the auxin action un the darker side. This fpon the stemact
to be positive, i.e., the growth of the
darker side is moplant arcs towards thre intense e lighter side. Inand the (^)
the root (when submitted general experimentally) the auxin actionto light, in (^)
is negative (over the positive range),
the growth oinhibited and the root curves towarf the darker side is (^) ds
this side.
- What are the types of
plant geotropisms? Why do
the stem and the root present
opposite geotropisms?
The types opositive geotropism, that if geotropisms are then which (^) the
plant grforce, as fows in favor of the gravitationalor example in roots, and the
negative geotropism, that against the
gravitationalstem. force, for example, in the
Root gare opposed due to differenteotropism and stem geotropism
sensitivities to auxin concentration in
these structures. Texperiment can demonstrate thhe following (^) e
phenomenon: Stem and root are placed
in a horizontal pground) and naturally aosition (pauxinsrallel to the
concentrate along their bottom part.
Under this condition it is observed that
the stem ggrows downwarrows uds. This happenspwards and the root
because in the stem the high auxin
concentration iside grow (longitudinally) morn the bottom make and thees this (^)
structures arcs upwards. In the root the
high auxin concentration inhibits the growth of this side and thein the bottom
upper side grows more making the root
to curve downwards.
- What is thigmotropism?
Thigmotrogrowth of the plant in pism is the movemresponse toent or
mechanicalcontact), as when a plant g stimuli (touch or rows arophysicalund (^)
a supporting rod. It occurs for example
in grape and passionfruit vines, etc.
- What is photoperiod?
Photoperiod is thlight exposure of a living e daily time pebeing. Theriod of
photoperiod may vary according to the
period of the year. - What is photoperiodism?
Photoperiodism isresponse presented by some livin the biological (^) g
beings to thexposure (photoperiod).eir daily time of light
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