All organisms are combined in the four kingdoms of nature: plants (about 500 thousand species), animals (about 1.5 million species), fungi (over 100

Biodiversity [Biological, life Earth]

All organisms are combined in the four kingdoms of nature: plants (about 500 thousand species), animals (about 1.5 million species), fungi (over 100 thousand species), and microorganisms (microscopic, often single celled). Organisms belonging to different kingdoms are closely interrelated.

Biological interaction (amensalism)

Plants are capable of forming organic substances from inorganic, thus releasing oxygen. Process, called the photosynthesis, is impossible without solar energy.

Animals are not able to create organic matter and get it by eating grass (herbivores) or animals (predators). Oxygen, excreted by plants, organisms use for breathing and carbon dioxide they emit is required for plants photosynthesis process.

The remains of plants and animals are decomposed by bacteria in the soil and converted into simple inorganic substances, which are absorbed by new generations of plants. Without bacteria — “nurses”, the remains of extinct animals and plants would cover the Earth with a layer of a few tens of meters.

Fuzzy boundaries

Despite the advances in construction of a natural system of the organic world, its perfection — is a continuous process. Every year scientists become aware of more and more kinds of modern and fossil organisms. This leads not only to new genera, families, orders, and even classes and phylums. It turns out that the boundary between the kingdoms of eukaryotes is not so clear, and there are many different organisms that simultaneously possess the key attributes of both plants and animals (e.g. euglena green) or animals and fungi. Not accidentally various systems range from 4 to 26 kingdoms, from 33 to 132 phylums, from 100 to 200 classes. The total number of species of living beings is estimated at several million. Taken from http://worldofschool.org

Cellular life

Currently, all living organisms are combined in Cell Empire as their common feature is a cell structure. Empire divided into two superkingdoms: pre-nuclear (prokaryotes) and nuclear (eukaryotes). The main criterion, by which organisms are divided into these major groups, is the cell structure. Eukaryotic organisms are characterized by a large number of cytoplasmic organelles that are absent in prokaryotes, and genetic unit is formed as a nucleus, which contains chromosomes.

In addition, eukaryotic organisms necessarily have cell multiplication by indirect division — mitosis, and multicellular eukaryotes have a sexual reproduction and reduction division — meiosis.