What are fossils? Fossils are the remains or preserved traces of animals, plants or other living things on rocks, such as body casts or parts thereof, tracks and footprints. The totality of fossils and their placement in rock formations and sedimentary layers is known as the fossil record. The word "fossil" derives from the Latin term "fossilis" which means "to be dug up".

In 1908 the English mathematician Godfrey H. Hardy (1877 - 1947) and the German physician Wilhem Weinberg concluded that if no evolutionary factor acted on a population that met certain conditions, the frequencies of their alleles would remain unchanged across generations. This principle became known as the Hardy-Weinberg law or theorem of gene equilibrium.

A plant needs a variety of factors, both internal and external, to grow and develop, and this includes differentiating into shapes, originating a variety of cells, tissues and organs. Examples of external factors affecting plant growth and development include light (solar energy), carbon dioxide, water and minerals, including atmospheric nitrogen (fixed by fixing and cyanophytic bacteria), temperature, length of day and gravity. .

Mutations that occur in living things are totally random, and sometimes genetic varieties emerge that can lead to the death of the carrier before birth or, if he survives, before reaching sexual maturity. These genes leading to carrier death are known as lethal alleles.

The word cell was first used in 1665 by the Englishman Robert Hooke (1635-1703). With a very simple microscope he observed pieces of cork, and realized that it was formed by empty compartments that he called cells. Animal cell is a cell that can be found in animals and is distinguished from the plant cell by the absence of cell wall and plastids.

Photosynthesis occurs in two major stages, which involve various chemical reactions: the first is the light phase (also called photochemistry) and the second is the dark phase (also known as the chemical phase). Generally speaking, the main events of photosynthesis are the absorption of light energy by chlorophyll; the reduction of an electron acceptor called NADP, which becomes NADPH 2; ATP formation and glucose synthesis The dark phase of photosynthesis need not occur in the dark.