ZOOLOGY STUDY GUIDE - Ye. O. Nevedomska - 2013

LECTURE 1. DIVERSITY OF THE ORGANIC WORLD

2. Structural levels of organization of living organisms

Levels of Organization of Living organisms are relatively homogeneous biological systems characterized by a specific type of interaction among their elements, as well as spatial and temporal scales of processes. The following levels of organization of living matter are distinguished: molecular, cellular, tissue, organ, organismal, and biological community levels (ranging from biogeocenoses to The Biosphere as a whole).

As complexity increases, a lower level becomes part of the next, higher level, which in turn becomes part of an even higher one, and so on. This is how THE PRINCIPLE OF hierarchy (stepwise subordination), inherent to living matter, is realized. The level of organization is fundamental to The Study of biological objects, which exist due to the connections that integrate their components into a single whole. METABOLISM/2.html">THE CONCEPT OF levels of organization of life helps explain the integrity and qualitative uniqueness of biological systems.

THE MOLECULAR LEVEL of organization of Living matter is the subject of molecular biology, which studies The Structure of Proteins, Nucleic Acids, Lipids, and other substances, as well as their role in cellular functioning. Practical successes in biotechnology and Introduction/32.html">Genetic Engineering have been achieved at this level.

A distinct level of organization of living matter is THE CELLULAR LEVEL; Cell biology is one of the major branches of modern biology, encompassing the morphological ORGANIZATION OF THE cell, cell specialization during development, cell Membrane Functions, and the mechanisms and Regulation of Cell division. Specialization (from French specialisation, from Latin specialis — special) is the acquisition of specific characteristics by Cells to perform particular functions.

At the Tissue and organ levels, the primary focus is on studying the structural features and functions of individual Organs and the Tissues that compose them, respectively.

At the organismal level, the Organism is studied as a single whole, the elementary unit of life, since life does not exist in nature outside of individual organisms. This involves studying the characteristic Structural Features of the organism, physiological processes and their neurohumoral regulation, and the mechanisms of Homeostasis and adaptation.

At the population-species level, researchers study the factors affecting population size, the conservation of endangered species, the dynamics of the genetic composition of populations, and the effects of microevolutionary factors.

At the biocenotic and biogeocenotic levels, the key areas of study are the relationships between organisms within biocenoses, the conditions determining their Abundance and the productivity of biocenoses, the Stability of the latter, and The impact of human activity on the conservation of biocenoses and their complexes.

At the biosphere level, modern biology addresses global issues, such as changes in atmospheric carbon dioxide concentrations associated with human activity.

Although the division of living matter and biological problems by levels of organization reflects objective reality, it is also conventional, as almost all specific biological tasks simultaneously concern several levels or even all of them. For example, the problems of evolution or ontogeny cannot be considered solely at the organismal level, i.e., without the molecular, cellular, organ-tissue, as well as population-species and biocenotic levels; similarly, The problem of population regulation relies on the molecular level but also extends to all higher levels, including aspects of the biosphere level.