Theory question 107
Hormonal Coordination(a) What is a hormone?
(b) Outline the role played by adrenaline in an emergency situation.
(c) In a tabular form, list five differences between hormonal co-ordination and nervous co-ordination.
(d) Name three animal hormones and two plant hormones.
Show the model answer
(a) A hormone is a chemical messenger made by an endocrine (ductless) gland, carried in the blood to a target organ where it produces a response.
(b) Adrenaline prepares the body for 'fight or flight': heart beats faster and stronger; breathing rate rises; liver changes glycogen to glucose, raising blood sugar; blood is diverted to the muscles; pupils widen; hairs stand on end; the person becomes alert.
(c) Hormonal vs nervous: chemical message vs electrical impulse; carried in blood vs carried along nerves (neurons); slow vs fast; response lasts long vs short-lived; effect may be widespread vs localised to particular muscles or glands; under involuntary control vs can be voluntary or involuntary.
(d) Animal (any three): insulin, adrenaline, thyroxine, oestrogen, testosterone, glucagon, growth hormone. Plant (any two): auxin (IAA), gibberellin, cytokinin, abscisic acid, ethylene.
Use a two-column table for (c).