1 Animals and plants have internal communication systems that allow information to pass between different parts of their bodies, and so help them to respond to changes in their external and internal environments. 2 Mammals keep their internal environment relatively constant, so providing steady and appropriate...

Gibberellins are plant growth regulators that are synthesized in most parts of plants (mainly in young leaves and seeds and in stems). They have a role in seed germination and controlling stem elongation.Stem elongationThe height for some plants is partly controlled by their genes. Tallness in pea plants is affected by...

Chemical communication in plantsPlant hormones or plant growth regulators are:- produced in a variety of tissues- move from cell to cell (by diffusion or active transport) or carried in xylem sap and phloem sapThe two types we're going to look at auxin and gibberellin.AuxinSynthesized in meristems (the growing tips of...

The Venus fly trap is a carnivorous plant that obtains a supply of nigtrogen compounds by trapping and digesting small animals, mostly insects.Anatomy of the Venus fly trapMidrib = hinge2 lobesglands that secrete digestive enzymes3 sensory hairs on each lobe that respond when they are deflectednectar-secreting glands to...

‘Birth control’ means taking control over if and when a couple have a child. It may involve:- contraception to prevent fertilisation- use of hormones to prevent pregnancies1. The birth control pillThe pill contains steroid hormones that suppress ovulation.These synthetic hormones break down more slowly in the body...

Hormones like adrenaline, insulin, glucagion and ADH- cell-signalling molecules- made in endocrine glands; glands are groups of cells that secrete (produce and release) one or more substances- passed directly into the bloodSteroid hormones are lipid soluble à pass through phospholipid bilayer and binds to receptor...