Most of the multicellular living organisms that inhabit the earth belong either to plants or to animals. It seems that the difference between them is so obvious that you can, without hesitation, determine this at a glance.
What is the difference between plants and animals
Any living organism belongs to any kind, genus, family, order, and so on. At the head of the unifying categories are the kingdom of plants and the kingdom of animals. Plants are able to create organic from inorganic substances in the process of photosynthesis and cannot move, animals eat plants and each other and actively move in search of food.
Karl Linney, creator of the classification of the animal and plant world, defined plants as organisms that grow and live, and animals - grow, live and feel. Such a division no longer meets the modern requirements of science.
Qualities inherent in all living things
In order to single out the world of living beings in nature, it is necessary to determine what traits are characteristic of all living organisms. First of all, it is a combination of the following qualities:
1. Living organisms are able to metabolize, remove metabolic products and in one way or another get the substances necessary for the continuation of life.
2. They can move or change the position of body parts in space.
3. Their descendants show signs of parental organisms.
4. Individuals of the same species differ from each other, and differences can be dependent and independent of heredity.
5. Organisms selectively respond to stimuli.
6. Most living things have the ability to grow, grow.
7. Throughout life, organisms undergo irreversible changes.
8. They can reproduce similar organisms.
What are the qualities of living everywhere
Many signs of living organisms, if taken separately, may be inherent in the world of inanimate nature. For example, crystals have the ability to grow, stones are very slow, but are destroyed, they can move from their original location over time. Air, water, planets and even galaxies are moving. Conversely, plant seeds for a very long time may not show their qualities and not differ from sand grains.
An important link connecting the world of animate and inanimate nature, are viruses that are not capable of metabolism, they can be obtained in the form of crystals, dissolved and recrystallized, and after all this they do not lose their biological properties. Signs of living organisms are, first of all, a more complex chemical composition and the presence of certain biological molecules in their structure. Special molecules of living organisms are proteins and nucleic acids.
Cheating plants
In nature, there are very unusual plants with atypical features, which makes it necessary to determine which characteristics are characteristic of animals and which are characteristic of plants. There are plants that cannot be distinguished from stones. They are similar to limestone, granite and white quartz. These plants are called lithops. As inhabitants of deserts, they rarely receive water and are able to exist, absorbing moisture from the fog.
It is known that plants are able to respond to irritation and produce substances that convey their sensations that plants produce plant hormones.
There are many plants that cannot carry out photosynthesis, but receive nutrients, luring and digesting insects and small animals. Among them - a sundew, a venus flytrap, which retained leaves and stems characteristic of plants, but with other functions.
There is also a ravenous plant, Rafflesia arnoldi, which has only a reddish-brown flower. The plant does not carry out photosynthesis, it does not have any parts inherent in the plant, only the structure of the cells allowed it to be attributed to this kingdom of living beings, and not to predatory animals.
How to distinguish plants from animals
In order to determine the affiliation of some organisms to a certain group of living beings, science must have an unambiguous answer to the question "what signs are characteristic of animals, what is their difference from plants". However, it is rather difficult to give an unambiguous answer about the difference between the representatives of the kingdom of plants and animals by external signs.
Modern taxonomy is forced to conduct complex research using the capabilities of related sciences. For this, methods of analysis of the genetic and molecular features of this species are used, as well as data on their embryonic development.
Animals not like animals
To determine the belonging of some sea creatures to the animal kingdom, it was necessary to clarify what signs of a living organism are characteristic of animals. Scientists needed more than one year for organisms that lacked the digestive system, which lived attached to the substrate and looked like strange flowers, to be counted among animals. Therefore, in order to correctly determine what kind of living creatures an unknown organism belongs to, it is necessary to determine what signs are characteristic of animals.
To determine the belonging of a group of marine invertebrates to a certain type of known organisms was so difficult that it was initially decided to place them in the realm of pogonophore. These organisms in the adult state are devoid of digestive organs, and outwardly they do not resemble animals in any way. Only a study of the peculiarities of their embryonic development made it possible to attribute them to annelids.
An attribute characteristic only of the animal kingdom
In the animal kingdom there are many organisms that are adapted to all kinds of living conditions. This altered their structure and appearance. To understand the tasks faced by zoologists involved in the modern systematics of living organisms, list the characteristics characteristic of animals. So, in most animals:
1. There is no photosynthesis, all these organisms are heterotrophic.
2. Food enters the digestive cavity through the mouth and is digested in specialized organs. Nutrition is active.
3. Animal organisms are able to move. When they live on some kind of substrate, this mode of existence is a secondary phenomenon.
4. The reaction to external irritation occurs in the form of a taxis in the absence of the nervous system or reflex in its presence.
In order to unequivocally answer what signs are characteristic of animals, it is necessary to determine what type of organisms we are talking about: unicellular or multicellular, chordate or vertebrate. Only for higher animals can we talk about such distinguishing features as:
1. The presence of several groups of tissues: integumentary, muscle, nervous and tissue of the internal environment.
2. The presence of the following organ systems: musculoskeletal, digestive, respiratory, excretory, genital, circulatory and nervous.
What is the difference between plants and animals at the microscopic level
In order to give a final answer to the question of the difference between the representatives of the two largest kingdoms, it is necessary to determine what characteristics are characteristic of animals, what is their difference from plants at the cellular level.
The main features that distinguish a plant cell:
1. In addition to the membrane, plant cells have a very solid cell wall consisting of fiber.
2. Spare carbohydrates in plants are deposited in the form of starch polysaccharide.
3. The cells have large vacuoles containing cell sap.
4. In the cytoplasm there are inclusions in the form of crystals of mineral salts.
5. Green plants contain plastids in their cells - chloroplasts in which photosynthesis takes place.
6. Digestive organs are absent, and food enters the plants by the osmotic route.
7. Reaction to external irritation in the form of tropism.
8. There is no ability to active movements.
9. During cell division, the constriction between them forms in the center and is distributed to the periphery.
It is also necessary to determine what characteristics are characteristic of animals at the cellular level.
1. The cell membrane is absent; there is a cell membrane, which is also present in plant cells.
2. The replacement polysaccharide is glycogen.
3. In animal cells, large vacuoles are absent. In simple organisms, there are small vacuoles that perform the function of digestion or excretion.
4. Inorganic salts in animal cells are usually dissolved.
5. In animal cells, there are no chloroplasts and no photosynthesis.
6. The constriction during cell division is formed from the edges and extends to the center of the cell.