A huge number of living creatures live on Earth. For the convenience of their study, researchers classify all organisms according to various criteria. By type of food, all living things are divided into two large groups - autotrophs and heterotrophs. In addition, a group of mixotrophs stands out - these are organisms adapted to both types of nutrition. In this article we will analyze the life features of the two main groups and find out how autotrophs differ from heterotrophs.
Autotrophs are organisms that independently synthesize organic substances from inorganic ones. This group includes some types of bacteria and almost all organisms belonging to the plant kingdom. In the course of their life, autotrophs utilize various inorganic substances coming from outside (carbon dioxide, nitrogen, hydrogen sulfide, iron and others), using them in the synthesis of complex organic compounds (mainly carbohydrates and proteins).
Heterotrophic organisms feed on prepared organic substances, they are not able to synthesize them on their own. This group includes fungi, animals (including humans), some bacteria, and even part of the plants (some parasitic species).
As we see, the main difference between heterotrophs and autotrophs lies in the chemical nature of the nutrients they need. The essence of the processes of their nutrition is also different. Autotrophic organisms spend energy when converting inorganic substances into organic substances, heterotrophs do not spend energy on nutrition. Autotrophs and heterotrophs are divided into two more groups depending on the energy source used (in the first case) and on the food substrate used by microorganisms of the second type.
Among autotrophs, photoautotrophic and chemoautotrophic organisms are distinguished. Photoautotrophs use the energy of sunlight to make transformations. It is important to note that a specific process occurs in the organisms of this group - photosynthesis (or a process of a type similar to it). Carbon dioxide is converted into various organic compounds. Chemoautotrophs use energy derived from other chemical reactions. Various bacteria belong to this group.
Heterotrophic microorganisms are divided into metatrophs and paratrophs. Metatrophs use dead organisms as a substrate of organic compounds, paratrophs use living organisms.
Autotrophs and heterotrophs occupy certain positions in the food chain. Autotrophs are always producers - they create organic substances that later pass through the entire chain. Heterotrophs become consumers of various orders (as a rule, animals fall into this category) and reducers (fungi, microorganisms). In other words, autotrophs and heterotrophs form trophic bonds between themselves. This is of great importance for the ecological situation in the world, since it is due to trophic bonds that the cycle of various substances in nature is carried out.