The plants respond to photoperiods due to the presence of :
enzymes
stomata
phytochromes
phytohormones
C.
phytochromes
Photoperiodism is the response of an organism to seasonal changes in day length.
It is regulated by the photoreversible pigment called phytochrome. Phytochrome is a photoreceptor chromoprotein.
In a plant organ which is covered by periderm and in which the stomata are absent, some gaseous exchange still takes place through
aerenchyma
trichornes
pneumatophores
lenticels.
Cork cambium results in the formation of cork which becomes impermeable to water due to the accumulation of
resins
lignins
suberin
tannins.
Pruning of plants promotes branching because the axillary buds get sensitized to
ethylene
gibberellin
cytokinin
indole acetic acid.
Avena curvature test is a bioassay for examining the activity of
auxins
cytokinins
gibberellins
ethylene.
Gibberellins can promote seed germination because of their influence on
rate of cell division
production of hydrolyzing enzymes
synthesis of abscisic acid
absorption of water through hard seed coat
'Climacteric' is
a phenomenon related to fruit ripening
the condition of a plant when all its fruits are almost ripe
the condition of a plant when most of its leaves have turned yellow
none of the above
