The diversity of animals, their structure, features of life and behavior, reproduction, development, their origin and evolution, distribution, significance in nature and human life are studied by zoology - the science of animals. Animals have a lot common features with representatives of other kingdoms. For example, animals and plants have a cellular structure similar to chemical composition(carbohydrates, lipids, proteins, nucleic acids, ATP, etc.), many general properties(metabolism, heredity, variability, irritability).
Representatives of this class are characterized by the presence of one or more flagella. The body of the flagellates is covered with an elastic sheath - the pellicle, which determines their shape. One or more cores. In some species of flagella, reproduction is only asexual, in others it is asexual and sexual. In the class there are representatives both with an autotrophic mode of nutrition (phototrophs) and with a heterotrophic one.
These are the most complex protozoa. Characteristic features organizations of ciliates are: movement with the help of cilia, the presence of two nuclei - large and small - with different functions and the sexual process - conjugation. Infusoria-shoe - an inhabitant of small stagnant reservoirs. Its length reaches 0.1-0.3 mm. It is covered with a pellicle, so the shape of the body is constant and resembles an elegant lady's shoe, hence its name (Fig. 10.3).
Presentation on the topic: Unicellular animals
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Presentation on the topic: unicellular animals
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The simplest are diverse (70 thousand species) unicellular animals living in water bodies and moist soil. Many of the simplest animals are as small and simple as some of the cells of large animals. But they differ from them in that they are able to live independently. Unicellular animals are a well-coordinated organism that provides nutrition, respiration, excretion, reproduction, growth, development and metabolism. Protozoa are very important consumers of bacteria and unicellular algae, as well as unicellular animals. The structure of protozoa (Fig. 1): 1-membrane, 2-cytoplasm, 3-contractile vacuole, 4-nucleus. The simplest can be divided into 4 systematic groups. These are rhizopods, radiolarians, sunflowers and sporozoans. Flagellates and ciliates are also isolated separately. 1 2 3 4 Fig. 1
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Sunflowers are one of the smallest groups of protozoa. It has only a few dozen species that live in fresh waters. The body of most sunflowers resembles the "sun", but is devoid of a mineral skeleton. Many sunflowers are free-floating, but there are also attached individuals. They feed on animal organisms. Solnechnik
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Radiolarians are single-celled, rarely colonial, free-living protozoa with a mineral skeleton in the form of amazingly beautiful formations. Bizarre outgrowths significantly increase the surface area of the body, which contributes to their movement in the water column. Radiolarians are distributed mainly in warm seas. radiolarians
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Amoeba lives in the silt at the bottom of small freshwater reservoirs. This small unicellular animal (0.2-0.5 mm), looking like a gelatinous lump, successfully competes with other protozoa. body covered plasma membrane. All actions of the amoeba are controlled by the nucleus. The cytoplasm is located in in constant motion. If its microflows rush to one point on the surface of the amoeba, a protrusion appears there. It increases in size, becomes an outgrowth of the body. This is a pseudopod that attaches itself to silt particles. All the contents of the amoeba gradually flow into it. This is how the amoeba moves from place to place.
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Amoeba Diet Amoeba is an omnivore. Its food consists of bacteria, unicellular plants and animals, as well as decaying organic particles. When moving, the amoeba encounters food and flows around it from all sides, and it ends up in the cytoplasm (Fig. 2). A digestive vacuole is formed around the food, where the digestive secrets that digest food enter. The vacuole with undigested food remnants moves to the surface of the body of the amoeba and its contents are thrown out. This way of capturing food is called cellular ingestion. Amoeba can also eat liquid food using another method - cellular nutrition. Rice. 2
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asexual reproduction amoeba Reproduction of amoeba is asexual and is carried out by dividing in two (Fig. 3). The nucleus is divided by mitosis first, then the constriction and elongation of the cytoplasm begins. In this case, the daughter chromosomes diverge to opposite poles and two identical daughter amoeba are separated from each other. Fig.3
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Cyst The amoeba feeds and reproduces in summer. In autumn, when cold weather sets in, the amoeba stops eating, its body becomes rounded, a dense protective shell is released on its surface - a cyst is formed. The same thing happens when the reservoir dries up. In the state of a cyst, the amoeba endures unfavorable living conditions for it. On the onset favorable conditions the amoeba leaves the cyst shell (Fig. 4). She releases pseudopods, begins to feed and multiply. Cysts carried by the wind contribute to the settlement of amoebas. Fig.4
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Working on this presentation, I learned a lot about protozoa, something that is not written in a biology textbook. It was interesting to create this presentation, because there is not much information about the simplest information and I had to look through a large number of information and choose the most important and place in this work. It turned out that protozoa are not so simple at all and their world is amazing and diverse! I hope my presentation will help you to get to know these little animals better!
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All organisms on Earth are divided into two large groups- cellular and non-cellular. The latter include only viruses, and the former include all other living beings. Cellular can be eukaryotes (they have a structure or prokaryotes (there is no nucleus). The latter are represented by bacteria, and the former include all other groups of creatures. The structure of most of them consists of many cells, but they exist in this group unicellular organisms, plants, mushrooms and even animals. The latter include amoeba, infusoria, and fungi - yeast, mucor, penicillium.
Cell structure of unicellular plants
These organisms are eukaryotes, that is, their DNA is located in the nucleus, which performs a protective function. Like all plant cells, they contain specific organelles such as vacuoles and plastids. Also, their structure includes mitochondria, lysosomes, ribosomes, the Golgi complex and the endoplasmic reticulum, that is, a set of organelles that is standard for all eukaryotes.
Functions of organelles
Mitochondria perform one of the most important roles in the cell - they produce energy for all life processes. Lysosomes are responsible for intracellular digestion of nutrients. The functions of ribosomes are to synthesize proteins from individual amino acids.
In the Golgi complex, some molecules are synthesized and all the substances produced by the cell are sorted.
The endoplasmic reticulum is also involved in metabolism, accumulating minerals, synthesizing lipids and phospholipids. Organelles that are inherent only also perform equally important functions. In chloroplasts, the process of photosynthesis takes place, and vacuoles act as a reservoir for substances that are unnecessary to the cell.
unicellular plants. Examples
Such organisms belong to the class of algae. The most striking example of a single-celled plant is Chlamydomonas. This includes chlorella and different kinds diatoms.
Structural features
unicellular plants different types have their distinctive features. Although they all consist of one cell, they may have their own specific features.
Chlamydomonas - the most famous representative They differ from others in that they have organelles such as a light-sensitive eye, with which organisms can determine where there is more solar energy for photosynthesis. Instead of numerous chloroplasts, they have one large one called a chromatophore. Also included in their structure contractile vacuoles. They act as pumps that pump out excess fluid. In addition, they have two organoid flagella that allow the body to move towards the light. Another single-celled plant is chlorella.
Like chlamydomonas, they belong to but do not have as many special organelles as the organisms described above. Their cells are typical plant cells.
Also refer to unicellular plants. They are the main component of plankton living in large water bodies. They have a specific cell wall that protects the body from external environment. It consists of iron dioxide, aluminum and other compounds. Many minerals are formed from the remains of these shells. Most unicellular plants reproduce by division. All this kind organisms make their own nutrients in the process of photosynthesis, that is, they are autotrophs.