Control & Coordination - 1 - UPSC

Iodine is an important constituent of hormone thyroxine. Its deficiency causes enlargement of thyroid gland (Goitre).

Within the structure of the papillae are taste buds that contain specialized gustatory receptor cells for the transduction of taste stimuli. These receptor cells are sensitive to the chemicals contained within foods that are ingested, and they release neurotransmitters based on the amount of the chemical in the food.

• Auxins promote stem elongation, inhibit the growth of lateral buds (maintains apical dominance). They are produced in the stem, buds, and root tips. Example: Indole Acetic Acid (IA). Auxin is a plant hormone produced in the stem tip that promotes cell elongation.
• Auxins are a powerful growth hormone produced naturally by plants. They are found in shoot and root tips and promote cell division, stem and root growth.
• Auxin and ethylene interaction have shown influence during fruit growth and ripening.
• As is the case during embryogenesis, auxin and cytokinin play
  a major role in postembryonic development. Cytokinin reporters are expressed in the procambium, whereas auxin reporters mark the xylem cells.

Rapid growth in cells of tendril cells away from support results in bending of tendril towards support.

The Mimosa plant(or touch-me-not plant) folds the leaflets on stimulus with touch. The stimulus is passed on to the entire branch and then the whole plant with all the leaflets close. There is a loss of water from the cells at the base of the leaf. 

Thyroxin is secreted by thyroid gland. Testes secrete male hormone testosterone.

Spinal cord acts as the main center for reflex actions. Spinal cord acts as a link between spinal nerves and brain. Thus it participates in conscious actions. Reflex actions is defined as an involuntary action performed by muscles under the direction of spinal cord in response to the stimulus.

The tissues of style secrete certain chemicals and the pollen tube moves toward these chemicals.