Plant Growth and Development Test - 6

This particular movement is observed in twiners and climbers. This results in curvature and helps in twinning around the support.
 

Physiological dormancy inhibits embryo growth and seed germination until chemical changes take place. It is an endogenous dormancy.
 

 There have been over 90 GA's isolated, all of which are most likely not essential to the plant. Instead, these forms are probably inactive precursors or breakdown products of active gibberellins.

Increase in length of a plant can be measured by an instrument called auxanometer. Arc-auxanometers have a wire fixed, with the plant apex on one end and a dead-weight on another. It passes over a pulley that has a pointer attached to it. The the height of the plant increases, the pulley rotates, and the pointer moves on a circular scale, to directly give the magnitude of the plant's growth. Sensitive auxanometers allow measurement of growth as small as a micrometer, which allows measurement in growth of response to short-term changes in atmospheric composition.

Phototropism is the ability of a plant, or other photosynthesizing organism, to grow directionally in response to a light source.
Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism.

In certain angiospermic herbaceous perennials, like banana and gladiolus, the part of the shoot above the ground dies each year after flowering and fruiting, but the underground parts (stem and roots) survive and put out new shoots the next year.

Secondary dormancy occurs in some non-dormant and post-dormant seeds that are exposed to conditions that are not favorable for germination, like high temperatures. It is caused by conditions that occur after the seed has been dispersed.

Ethylene is widely used in the ripening of fruits.It is also responsible for the changes in texture, softening, color, and other processes involved in ripening.

The delay of senescence of leaves and other organs of the plants by cytokinins is called Richmond Lang effect.

This plant hormone restricts shoot branching in the plant.