The neuron is the functional unit of the nervous system.
A reflex action or reflex is a biological control system linking stimulus to response and mediated by a reflex arc.
Some involuntary co-ordinations continue to occur all the time without our being aware of them, e.g. working of heart, lungs and most other internal organs. This part of the nervous system is called autonomous, i.e. it works all by itself.
The dorsal and lateral sides of the mid brain are thickened to form two pairs of optic lobes which collectively constitute the corpora quadrigemina.
The hypothalamus contains nuclei that control hormonal secretions from the pituitary gland.
Auxins are responsible in promoting cell elongation, a process that is required before differentiation of a cell.
Cytokinin induces rapid mitosis in developing seedling, promotes cell division
Gibberellins initiate stem growth and root growth , tAbscisic acid inhibits shoot growth in plants and promotes stomatal closure .
Ethylene is a gaseous hormone which induces fruit ripening and flowering in plants.
Originally phototropism was called heliotropism, because the plant grows towards the sun.
The shoot tip illustrates negative geotropism (grows against force of gravity) while the root tip exhibits positive geotropism (grows toward the force of gravity).
The pituitary gland, located at the base of the brain just beneath the hypothalamus, is considered the most important part of the endocrine system.
The pancreas consists of a special type of tissue called Islets of Langerhans which has alpha and beta cells producing two important hormones, glucagon and insulin respectively.
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