There are many systematic groups of living organisms. Their classification is based on various characteristics. One of them is the type of food. Heterotrophs, autotrophs - what is it? We will find the answer in the article.
To eat is to live
Nutrition is one of the main signs of living organisms. The processes of metabolism and energy conversion, growth, development are impossible without the intake of nutrients. Representatives of each kingdom of wildlife in their own way adapted to receive them.
Types of food organisms
Autotrophs and heterotrophs are the main groups of organisms by type of nutrition. The first of them includes plants and cyanobacteria, the second - animals and fungi.
Heterotrophs can only eat ready-made substances. They are organic (proteins, lipids, carbohydrates) and inorganic. Examples of the latter are mineral salts. Animals for their transformation have special structures of varying complexity of organization. The simplest unicellular organisms, such as ciliates or amoeba, have digestive vacuoles. In the intestinal hydra there are cells of the same name. Mollusks and arthropods already have specialized organs. But the most perfect digestive system is in mammals. It consists not only of the tract, but also of the glands, the enzymes of which help the breakdown of large biopolymer molecules. Only parasitic worms do not need this system. They attach to the intestinal ducts and absorb already processed food.
Autotrophs: what is it
If you translate this term from the Greek language, it is easy to understand what will be discussed. "Auto" means "himself", "trophos" - "food". Indeed, these organisms themselves produce the necessary substances.
Autotrophs are organisms that use the energy of solar radiation to produce carbohydrates. But for the course of this process, certain conditions are necessary.
The essence of photosynthesis
This process occurs only in green plastids - chloroplasts, which determine the corresponding color of certain plant organs. A prerequisite is also the presence of light, water and carbon dioxide.
Plants are autotrophs that carry out a complex chemical reaction. But its essence is simple: glucose and oxygen are obtained from water and carbon dioxide . It is simply impossible to overestimate their role in nature. After all, autotrophs are organisms thanks to which the process of respiration is possible, which means the existence of all life on the planet.
Photosynthesis is a rather complex process, proceeding in two phases. The first takes place in the light, the second - in the dark, but always in the chloroplasts of green leaves. Carbon dioxide penetrates through holes in the integumentary tissue called stomata. With their help, breathing and transpiration also occur - the evaporation of water from the surface of a plant.
Glucose resulting from photosynthesis is a simple carbohydrate - a monosaccharide. If the molecules of this substance repeatedly combine, a complex biopolymer of starch is formed. It is he who is deposited in reserve by plants "for a rainy day." This also explains the fact that all plant foods are rich in carbohydrates, which easily begin to break down already in the oral cavity.
And then the question immediately arises: do the autotrophs themselves breathe? After all, this process is the opposite of photosynthesis. Of course, yes, because plants are living things. The secret is that the intensity of their release of oxygen is much greater than carbon dioxide. However, if indoor plants are placed in a room where sunlight does not penetrate, they will only breathe. It is undesirable to be in such conditions.
Who are chemotrophs
Autotrophs are not the only group of organisms capable of independently producing “food” for themselves. Their variety are chemotrophs. To obtain the necessary substances, they do not use sunlight, but the energy of chemical bonds. These include nitrogen - fixing nodule bacteria that develop on the roots of representatives of the legume and cereal families. Serobacteria are also widely known.
They oxidize the corresponding chemical compounds, and the resulting energy is spent on vital processes.
Mixotrophs and the complexity of taxonomy
But there are especially "cunning" organisms. Agree, the conditions for photosynthesis are not always there. Drought or lack of light are serious obstacles to its passage. And there are cases of the lack of ready-made organic substances. It would be very convenient to be both an autotroph and a heterotroph at the same time - to create a mix of food methods. But is it possible? Sure. Mixotrophs - the so-called organisms that have both chloroplasts and the ability to absorb finished substances. A striking example of this is unicellular euglena green.
A predatory plant, sundew, however, is certainly an autotroph. As a heterotroph, it acts, eating its prey from a special hunting device.
By the way, it is the type of nutrition that is the main sign of determining the affiliation of organisms to a plant or animal community. For example, the unicellular alga Chlamydomonas actively moves, thanks to the presence of flagella, and has a photosensitive eye. What is not an animal? However, in her cell there is a horseshoe-shaped chloroplast, which determines her belonging to the kingdom of plants.
The situation is more complicated with mushrooms. They are not capable of photosynthesis, do not have plastids and do not store starch in reserve. But the attached lifestyle, unlimited growth and the presence of the cell membrane does not allow us to call them animals. Therefore, the taxonomists identified them in a separate kingdom.
Autotrophs are amazing organisms. Being the intermediary between the sun and the earth, it is they who make life on our planet possible.