Questions:
1. Based on what signs can we say that an amoeba cell is an independent organism?
2. Describe the processes of nutrition and excretion in amoeba.
3. Explain the role of protozoa in nature.
4. Establish a connection between the habitat and food types of green euglena.
5. Compare the methods of reproduction of amoeba protea and green euglena.
6. Give reasons for the statement about the intermediate position of green euglena between the two kingdoms of living nature.
7. What is the increasing complexity of the organization of colonial forms of flagellates? Explain your answer with examples.
8. Prove with specific examples that ciliates have a more complex structure than sarcodes and flagellates.
9. Establish a connection between the increasing complexity of the structure of the ciliate-slipper and the processes of nutrition and excretion.
10. Describe the features of the reproduction process of the ciliate slipper.
11. Explain why the sexual process is not sexual reproduction. What is its biological significance?
12. Explain what functions a protozoan cell performs.
13. Name measures to prevent the disease from amoebic dysentery and malaria.
14. Formulate a conclusion about the role of protozoa in nature and their influence on humans.
15. Explain why a protozoan cell is an independent organism.
16. Describe the habitats of unicellular organisms. What condition is necessary for their existence?
17. Explain what the functions of vacuoles are in the body of unicellular organisms.
18. Establish the relationship between the structure and methods of movement of unicellular organisms.
19. Name the features of protozoan adaptation to unfavorable conditions.
20. Describe the role in nature of two or three representatives of protozoa living in the aquatic environment.
21. Name measures to prevent diseases caused by protozoa.
22. Name the scientist who was the first to describe a group of simple animals.
23. What is common in the structure of protozoa?
24. Why do scientists say that animals and plants had common ancestors?
25. Explain in what sense doctors often use the expression “diseases of dirty hands.” Give examples of diseases to which it refers.
26. Complete the sentences by filling in the necessary words.
If you keep a jar of... for several days in a dark closet, the color will disappear. ... will become light, but will not die, since in the dark they feed like... . In the light... again... and they will start to eat like... .
27. Fill in the missing letters. Give definitions of concepts.
S..mb..oz - ...
K..lonia - ...
Cancer...guilt -...
Ts..sta - ...
28. Explain how the diet and lifestyle of a protozoan are related to each other.
29. Is the statement true: “The school chalk, the walls of the palace and the walls of the pyramid have one source, one basis? Prove your point of view.
Which statements are true?
1. The protozoan cell acts as an independent organism.
2. Reproduction in the amoeba is asexual, and in the ciliate slipper it is both asexual and sexual.
3. The organelles of movement of the ciliate slipper are the pseudopods.
4. Euglena green is a transitional form from plants to animals: it has chlorophyll, like plants, and feeds heterotrophically and moves like animals.
5. Amoeba has two types of nuclei in the body.
6. The small nucleus of ciliates is involved in sexual reproduction, and the large one is responsible for vital activity.
7. Dysenteric amoeba is carried by mosquitoes.
1. What structure does a protozoan cell have? Why is it an independent organism?
A protozoan cell performs all the functions of an independent organism: it feeds, moves, breathes, processes food, and reproduces.
2. In what environments do unicellular organisms live? Why is the presence of water a prerequisite for their existence?
Protozoa live only in an aquatic environment, because they breathe oxygen dissolved in water and can only move in a liquid environment.
3. What is the function of vacuoles in the body of unicellular organisms?
In the body of unicellular organisms there are digestive and contractile vacuoles. Digestion of food occurs in the digestive vacuole, and the contractile vacuole removes harmful substances and excess water from the cell.
4. Name the organelles of movement. What are the modes of movement of unicellular organisms?
The amoeba moves with the help of pseudopods, as if flowing. Euglena green moves due to the rotation of the flagellum, and ciliates move due to the oscillatory movements of the cilia.
5. How do protozoa reproduce? Briefly describe these methods.
Representatives of the Phylum Sarcodae and flagellates reproduce asexually. First, the nucleus is divided in half, and then a constriction is formed, dividing the cell into two full-fledged organisms.
The protozoa of the Ciliates type are characterized by a sexual process in which the number of individuals does not increase. The sexual method redistributes genetic material between individuals and increases the vitality of organisms.
6. How do protozoa tolerate unfavorable conditions?
When unfavorable conditions occur (low water temperature, drying out habitat), the protozoa secrete a protective shell around themselves - a cyst. In the cyst state, the organism can wait for favorable conditions to arise or, with the help of the wind, be transported to another habitat.
7. Name two or three representatives of protozoa that live in the marine environment. What role do they play in nature?
Radiolarians and foraminifera live in the marine environment. They participate in the formation of sedimentary rock layers.
8. Name the diseases known to you that are caused by protozoa, and measures to prevent these diseases.
Amoebic dysentery, malaria. To prevent these diseases, you should follow the rules of personal hygiene, thoroughly wash fruits and vegetables before eating, and use mosquito repellents.
Which statements are true?
1. The protozoan cell acts as an independent organism.
2. Reproduction in the amoeba is asexual, while in the slipper ciliate it is both asexual and sexual.
4. Euglena green is a transitional form from plants to animals: it has chlorophyll, like plants, and feeds heterotrophically and moves like animals.
6. The small nucleus of ciliates is involved in sexual reproduction, and the large one is responsible for vital activity.
Scientists believe that the first inhabitants of the Earth were precisely these organisms: archaea and bacteria. Despite all their ancient origins, they were discovered quite recently, with the invention of optical magnification of objects using a microscope (A. Leeuwenhoek). A unicellular microorganism consists, accordingly, of one cell, in contrast to a multicellular one. Many bacteria, some fungi and algae have this simple structure. Thus, this category is unsystematic, including representatives of several
Prokaryotes and eukaryotes
The former do not have a clearly formed nucleus in the cell and other organs, for example, the nuclear envelope and membrane organelles. They appeared on the planet in ancient times, believed to be more than three billion years. The second ones have a pronounced nucleus and protoplasm in the cell. According to hypotheses, they existed already two billion years ago. Moreover, all organisms, except archaea and bacteria, are nuclear (eukaryotes).
Unicellular habitats
The most numerous representatives of unicellular organisms are bacteria and archaea. The answer to the question of where they live is simple: everywhere! The main thing for these microorganisms is that the environment (or substrate) is suitable for life activities. Moreover, the main thing is the presence of sufficient humidity, the presence of water. By the way, if the conditions are unfavorable, it doesn’t matter: many of the bacteria can form spores, which are a special form of existence, “preserved”. In what environments do single-celled bacteria live? In the atmosphere, in soil, in water, in other organisms. Let's take a closer look.
In the soil
If we talk about the environments in which unicellular organisms live, then the soil contains the largest number of them. Humus, chernozem and other soils, which are favorable substrates, have everything for optimal life activity: nutrients, a certain amount of liquid. There is also no direct sunlight here, but there is a comfortable temperature regime, allowing single-celled organisms to develop and reproduce well. Most of these bacteria perform the functions of transforming dead organisms, decomposing them into their component parts - microelements and compounds. Saprophages (the so-called bacteria that feed on remains) participate in the formation of fertile humus. However, among the beneficial bacteria there are also pathogenic ones. For example, the causative agents of tetanus and botulism, which can enter the human body through various skin lesions.
In water
Speaking about the environments in which single-celled bacteria live, one cannot fail to mention the expanses of water that cover most of the territory of planet Earth. This is where they are mostly washed away from the soil. So, in water, especially standing water, just like in soil, there can be millions of bacteria (in a few grams of liquid). The community cannot do without harmful single-celled organisms. Among them are the causative agents of typhoid, dysentery, cholera and other serious diseases for humans.
In the air
There are not many single-celled representatives here, but there are plenty. It is known that many infectious diseases are transmitted mainly by airborne droplets. And these single-celled organisms enter the air with dust particles and micro droplets of water lifted by air currents. Scientists have discovered that bacteria can “fly” in a similar way to the very boundaries of the Earth’s atmosphere. Some of the unicellular organisms feel quite good in a vacuum, forming preserved life forms - spores.
On the skin and inside us
In what other environments do single-celled microorganisms live? A lot of bacteria are found on human skin, in some of its areas: armpits, perineum, mucous membranes. About three kilograms of live weight of bacteria “live” inside the average citizen. A huge army of organisms (in a quantitative sense - billions) that cannot be ignored. Basically, these are friendly neighbors who form the microflora of a healthy person. But there are also pathogenic ones, which under certain conditions can cause enormous harm.
Final test of knowledge on the topic
- What is the structure of a protozoan cell? Why is it an independent organism?
- In what environments do unicellular organisms live? Why is the presence of water a prerequisite for their existence?
- What are the functions of vacuoles in the body of unicellular organisms?
- Name the organelles of movement. What are the modes of movement of unicellular organisms?
- How do protozoa reproduce? Briefly describe these methods.
- How do protozoa survive unfavorable conditions?
- Name two or three representatives of protozoa that live in the marine environment. What role do they play in nature?
- Name the diseases known to you that are caused by protozoa, and measures to prevent these diseases.
Which statements are true?
- The protozoan cell acts as an independent organism.
- Reproduction in the amoeba is asexual, while in the slipper ciliate it is both asexual and sexual.
- The organelles of movement of the ciliate slipper are the pseudopods.
- Euglena green is a transitional form from plants to animals: it has chlorophyll, like plants, and feeds heterotrophically and moves like animals.
- Amoeba has two types of nuclei in the body.
- The small nucleus of ciliates is involved in sexual reproduction, and the large one is responsible for vital functions.
- Dysenteric amoeba is transmitted by mosquitoes.
- The definitive host of Plasmodium falciparum is humans.
Typically, when searching for habitable planets and life on other planets, scientists look for biosignals from atmospheric carbon dioxide. On Earth, atmospheric carbon dioxide increases surface temperatures through the greenhouse effect. Carbon also moves into the subsurface and back into the atmosphere through natural processes.
“Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled out of the atmosphere and absorbed by surface rocks and sediments,” said Bradford Foley, assistant professor of geosciences. “Balancing these two processes keeps carbon dioxide at a certain level in the atmosphere, which is essential for our planet to maintain a temperate, habitable climate.”
Most of Earth's volcanoes lie on tectonic plate boundaries, which is one of the reasons scientists believed their existence was necessary for life to exist. The point was that one plate goes deeper into the surface under the influence of a collision with another plate and this affects the carbon cycle because it introduces carbon into the mantle.
Planets without tectonic plates are known as stagnant planets. On these planets, the crust is one giant spherical plate floating on the mantle, and does not consist of separate parts. They are considered more common than planets with plate tectonics. At the same time, the Earth is the only planet on which the very existence of tectonic plates has been confirmed.
Foley and Andrew Smye, assistant professor of geosciences, created a computer model of the planet's life cycle. They looked at how much heat its climate could retain depending on the initial heat reserve, or the amount of heat-producing elements formed during the planet's formation. We are talking about elements that release heat at the moment of decay. On Earth, decaying uranium produces thorium and heat, and decaying thorium produces potassium and heat.
After running hundreds of simulations that varied the size and chemical composition of the planet, the researchers found that stagnant planets could support conditions for liquid water for billions of years. In the most extreme case, they could support life for 4 billion years, that is, the entire current period of the Earth's existence.
“Monolithic planets also have volcanism, but the processes are much shorter than on planets with plate tectonics because there are no moving dynamics,” Smy said. “Volcanoes result in a succession of lava flows that are layered on top of each other over time, like layers of a cake. The heating of rocks and sediments is much greater at depth.”
Ultimately, the researchers discovered that at high enough temperature and pressure, carbon dioxide can escape from rocks to the surface, a process called degassing. On Earth, according to Smy, the same process occurs with water in subduction fault zones.
This degassing process increases depending on what types and quantities of calorific elements are present in a certain place on the planet.
According to the researchers' model, which was published in the July issue of Astrobiology, the presence and amount of calorific elements were much better indicators of a planet's potential to support life.
