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 Roots of the seedling of first trough are straight.
 Roots of the second trough in which clay pot filled with water was placed have
bent towards the side at which clay pot was placed.
 This shows that roots of a plant grow towards water.

Plant Hormones

 The control and coordination system in plants is done by plant hormones.
They affect the growth of a plant in one or the other aspect
 The four types of plant hormones responsible for control and
coordination in plants are:

 1) Auxin
 2) Gibberellin
 3) Cytokinin
 4) Abscisic acid (ABA)

Auxins

 Auxins hormone controls a plant response to light and gravity.
 It is made by the cells present at the tip of a stem and roots.

 When plants detect light then it diffuses towards the shady part and
stimulates the cell to grow longer.

 Hence, plants appear to bend towards light

Gibberellins
 Gibberellins hormone works in the presence of auxin hormone
 Promotes cell enlargement and cell differentiation.