Answer is the phylum is Pteridophyta. Pteridophytes are first land plants, examples ferns, <em>Lycopodium, Selaginella. </em>Members have liginified cells and developed conducting tissues called vascular system to conduct water and synthesized food. They reproduce through spores, seeds do not develop in pteridophytes.
These are known as Hormones. Hormones are chemical messengers that are released in one tissue normally endocrine glands for example, adrenal glands, pituitary glands, and transported in the blood stream to alter the activities of specific cells in other tissues. Hormones serves as messengers, controlling and coordinating activities or processes such as growth, metabolism and fertility in the body.
Once this initial energy is added, the wave travels through the medium until all its energy is transferred. In contrast, electromagnetic waves require no medium, but can still travel through one.
The pH scale is a logarithmic one, meaning that each pH unit has 10 times as many hydrogen ions as the unit above it. So, at pH 4, there are 10 times more hydrogen ions than at pH 5 and 100 times more hydrogen ions than at pH 6.
Esta teoría hace referencia al movimiento actual de las placas que sustentan los continentes y que se desplazan a lo largo de millones de años. En toda la historia geológica de la Tierra, los continentes no han estado siempre en la misma posición. Existe una serie de evidencias que veremos posteriormente que ayudaron a Wegener a refutar su teoría. El movimiento se debe a que continuamente está formándose nuevo material procedente del manto. Este material se crea en la corteza oceánica
