Diversity and importance of algae in nature. Seaweed

Lesson type - combined

Methods: partially search, problem presentation, reproductive, explanatory and illustrative.

Target:

Students’ awareness of the significance of all the issues discussed, the ability to build their relationships with nature and society based on respect for life, for all living things as a unique and invaluable part of the biosphere;

Tasks:

Educational: show the multiplicity of factors acting on organisms in nature, the relativity of the concept of “harmful and beneficial factors”, the diversity of life on planet Earth and options for adaptation of living beings to the entire range of environmental conditions.

Educational: develop communication skills, the ability to independently obtain knowledge and stimulate one’s cognitive activity; ability to analyze information, highlight the main thing in the material being studied.

Educational:

Formation of an ecological culture based on recognition of the value of life in all its manifestations and the need for a responsible, careful attitude towards the environment.

Forming an understanding of the value of a healthy and safe lifestyle

Personal:

nurturing Russian civic identity: patriotism, love and respect for the Fatherland, a sense of pride in one’s Motherland;

Formation of a responsible attitude towards learning;

3) Formation of a holistic worldview that corresponds to the modern level of development of science and social practice.

Cognitive: ability to work with various sources of information, transform it from one form to another, compare and analyze information, draw conclusions, prepare messages and presentations.

Regulatory: the ability to organize independent completion of tasks, evaluate the correctness of work, and reflect on one’s activities.

Communicative: Formation of communicative competence in communication and cooperation with peers, seniors and juniors in the process of educational, socially useful, educational and research, creative and other types of activities.

Planned results

Subject: know the concepts of “habitat”, “ecology”, “ecological factors”, their influence on living organisms, “connections between living and non-living things”;. Be able to define the concept of “biotic factors”; characterize biotic factors, give examples.

Personal: make judgments, search and select information; analyze connections, compare, find an answer to a problematic question

Metasubject:.

The ability to independently plan ways to achieve goals, including alternative ones, to consciously choose the most effective ways to solve educational and cognitive problems.

Formation of semantic reading skills.

Form of organization of educational activities - individual, group

Teaching methods: visual-illustrative, explanatory-illustrative, partially search-based, independent work with additional literature and a textbook, with COR.

Techniques: analysis, synthesis, inference, translation of information from one type to another, generalization.

Multicellular algae. The diversity and importance of algae

Objectives: to continue to develop an understanding of algae as a special group of plant organisms; introduce various multicellular algae, their habitat and structural and reproductive features; give an idea of ​​the role of algae in nature, their use in science, technology, human economy, and measures to protect algae; continue to develop the ability to work with a microscope and the skill of performing biological drawings.

Equipment and materials: tables: “Single-celled algae”, “Multicellular algae”, “Brown and red algae”, flowering plant Elodea from an aquarium, herbariums of various multicellular algae, live algae from an aquarium; some items made from seaweed: seaweed salad, seaweed supplements, iodine, agar-agar, etc.

Key words and concepts: filamentous algae (ulotrix, cladophora, spirogyra), brown algae (kelp, fucus, sargassum), red algae (phyllophora, porphyra, ptilote, radimenia); thallus (thallus), rhizoids, sporangium, nucleus with nucleus, vacuole, chromatophore; asexual reproduction, sexual reproduction, conjugation; zoospores, motile gametes, spores, zygote; phytoplankton

During the classes

Updating knowledge

Work at the board

Two students are called to the board. One of them needs to depict the structure of the unicellular green alga Chlamydomonas, and the other - Chlorella and indicate the main organelles of this algae. It takes about 2-3 minutes to complete the task. Afterwards, students respond orally according to the diagram drawn.

Next, three more students come to the board. One of them depicts a diagram of the asexual reproduction of Chlamydomonas, the other - the sexual reproduction of Chlamydomonas, and the third - the reproduction of Chlorella. Afterwards, students respond orally according to the diagrams they have drawn.

Learning new material

Teacher's story with elements of conversation

In the last lesson we studied unicellular algae. Today let's move on to multicellular ones. Let's start with filamentous algae.

Why do you think they got this name? (Answers from students.)

These algae resemble long threads in appearance.

Among filamentous algae, the most common in our latitudes is spirogyra. This is a multicellular green algae, the cells of which are arranged in one row. Growth occurs through division of the entire body. The plant leads unattached Lifestyle. Its threads move freely in water under the influence of various currents. This is a common inhabitant of our ponds and rivers with gentle currents. You, often swimming in a pond or river, have probably discovered accumulations of green, slippery to the touch mud. These are the filaments of Spirogyra.

(The teacher shows an image of this algae on the tables and, if possible, in live or dried form.)

Spirogyra cells have an elongated shape. On the outside they are covered with a layer mucus.

Why do you think this algae received such a name? (Students express their guesses.)

Chromatophores in the cells of this algae they have a special structure. They are long, elongated and located in the cytoplasm along the cell wall, as if encircling it in a spiral. Hence the name. In the center of the cell there is a large nucleus with nucleolus. Takes up quite a lot of space vacuole

Remember in what ways unicellular green algae can reproduce. (Sexually or asexually.)

Spirogyra is also characterized by both sexual and asexual reproduction. At asexual method, the filaments of spirogyra break, the cells of each part begin to divide, giving rise to new young organisms.

When does asexual reproduction of Chlamydomonas occur? (Under favorable conditions.)

Spirogyra also reproduces asexually under favorable conditions, most often in summer.

Sexual The reproduction of Spirogyra is somewhat different from the identical Chlamydomonas. During sexual reproduction of Spirogyra, two filaments are located parallel to each other. Then they get closer and become enveloped in mucus. Cells located closest to each other form special outgrowths that connect, creating a channel through which the contents of one cell flow into another. Thus it happens fertilization and is formed zygote. The zygote is covered with a thick membrane and can remain dormant for a long time. After a certain period of dormancy, the zygote germinates and gives rise to a new organism. This method of sexual reproduction is called conjugation.

On stones and snags lying at the bottom of shallow rivers, you can often find another filamentous algae - ulotrix. Clumps of ulotrix look like bright green silky threads. The body of this plant also consists of one row of cells, but the cells are not elongated, like those of Spirogyra, but shorter. Ulotrix grows due to the division of cells located only at the top. In addition, this algae leads attached Lifestyle. It is glued to the substrate with a special colorless cell. In the cytoplasm of each algae cell one can detect a nucleus and a chromatophore in the form of an open ring.

Asexual Reproduction of this alga occurs through zoospores.

Remember what a zoospore is.

Zoospores- motile cells with flagella, with the help of which asexual reproduction occurs. Zoospores float freely, and then attach to the substrate, divide and give rise to a new organism.

What method of reproduction is most often found in algae under unfavorable conditions? (They reproduce sexually.)

During sexual reproduction of ulothrix, numerous motile gametes with flagella are formed in some algae cells. Gametes from different individuals fuse in pairs and form a zygote. The zygote is also covered with a thick membrane and can remain dormant for a long time. As soon as conditions favorable for algae life are created, the zygote divides into 4 spore cells. The spores sink to the bottom and, having attached themselves to the substrate, begin to divide, giving rise to a new individual.

Quite often, the multicellular green alga Cladophora is found in fresh and salt water bodies. It is also a filamentous algae, but more highly organized than Spirogyra and Ulotrix. Cladophora threads branch. Young cladophorans lead an attached lifestyle, but subsequently often break off and go free swimming. An interesting feature of this plant is the presence in each cell a large number of cores. Such phenomena never occur in the cells of higher plants.

Independent work of students with the textbook

Using the text of the textbook (textbook by I.N. Ponomareva § 39; textbook by V.V. Pasechnik § 12), as well as personal experience, indicate the importance of algae in nature and human life.

(About 3-5 minutes are allotted to complete this task, after which 2-3 students’ notebooks are taken for checking, and another 3-4 answer orally. The teacher accompanies the students’ oral answers by demonstrating tables and, if possible, some seaweed products: salad from seaweed, food supplements with algae, iodine, agar-agar, etc.)

The role of algae in nature

The process of photosynthesis transforms the energy of the sun into energy available to other organisms and releases the oxygen necessary for their respiration.

Food for many sea animals (sea urchins, fish, etc.) and sea waterfowl.

Shelter for fish and many other animals.

Enrichment of water with oxygen during photosynthesis.

Some types of unicellular algae are pioneer plants: when they fall on infertile substrates, they participate in soil formation.

Some types of algae are part of complex organisms (lichens).

The role of algae in human life and activity

Food products for humans (kelp, ulva).

Use as an additive to livestock feed.

Manufacture of fertilizers.

Preparation of agar-agar used in the food industry and microbiology (red algae).

Use in the chemical industry (production of iodine, potassium salts, alcohol, acetic acid, etc.).

Biological treatment of industrial and waste water (junk domonada, chlorella).

Obtaining medicines and biologically active food additives.

Harm caused by algae to humans and their activities

Excessive proliferation in irrigation canals makes it difficult to supply water.

Excessive reproduction in fish ponds makes seasonal fishing difficult.

Excessive growth of algae leads to difficulties in navigation.

Creative tasks.

Draw a picture of the underwater world, in which various sections of algae will be present: red, brown, green, etc.

Compose a fairy tale about life in the underwater kingdom, where the main characters will be algae.

In the books of which writers are there descriptions of the underwater world?

An activity for students interested in biology. Find in the specialized literature the names and descriptions of algae grown in fresh and salt aquariums. What algae do they belong to?

Seaweed. Educational film

Travel across Africa. Algae forest. Educational film.

MarineseaweedKelp

Seaweed and Green Technologies from Olmix - EN

Marineseaweed

Resources:

I.N. Ponomareva, O.A. Kornilov, V.S. Kuchmenko Biology: 6th grade: textbook for students of general education institutions

Serebryakova T.I.., Elenevsky A. G., Gulenkova M. A. et al. Biology. Plants, Bacteria, Fungi, Lichens. Trial textbook for grades 6-7 of secondary school

N.V. Preobrazhenskaya Biology workbook for the textbook by V. Pasechnik “Biology 6th grade. Bacteria, fungi, plants"

The main differences between lower plants and higher ones are as follows:

1. their body does not have organs, like those of higher plants - roots and shoots - and is represented by a thallus or thallus (this is due to the fact that algae absorb nutrients over the entire surface of the vegetative body);

2. there is no differentiation of cells into tissues;

3. The organs of sexual reproduction are in most cases unicellular.

The lower plants include a group of divisions (12 divisions) that unite simply organized plants - algae. Algae make up a group of lower plants that live mostly in aquatic environments. The term "algae" is not systematic, but ecological-biological. A group of divisions of algae unites divisions that differ from each other in origin.

General characteristics of algae

Origin of algae. Algae are the oldest representatives of plants, the age of fossil remains of which is about 3.2 billion years. During this period, these organisms went through a long and complex development path. Some representatives have evolved greatly, others, due to the conservatism of the aquatic environment, have remained virtually unchanged, therefore algae vary greatly in their organization.

Algae propagation. The reproduction of algae is very diverse. There are 3 ways of reproduction in algae:

1. Vegetative propagation is a method of reproduction in which new individuals arise from part of the mother’s organism (cell division, colony disintegration, filament rupture, etc.).

2. Asexual reproduction is a method of reproduction in which new individuals arise from specialized haploid cells - spores. The contents of the cell divide repeatedly and many spores are formed, each of which is capable of giving rise to a new plant. Spores can be motile (have flagella) or immobile.

3. Sexual reproduction is a method of reproduction in which two organisms take part and a new individual arises from a diploid cell - a zygote. A zygote is formed as a result of the fusion of two haploid cells - gametes. The zygote is covered with a thick shell, accumulates reserve nutrients and is able to withstand unfavorable conditions.

Algae feeding. Algae absorb all the substances necessary for nutrition (CO2 and minerals) and respiration (O2) from the water. Among algae, most feed autotrophically, but almost all (especially low-organized ones) are able to switch to mixotrophic (mixed) nutrition, and some can completely switch to heterotrophic nutrition (euglena). At the same time, their cells can completely lose chloroplasts, absorbing ready-made organic substances over the entire surface of the cell. Interestingly, when conditions favorable for photosynthesis occur, algae restore chloroplasts and their ability to carry out photosynthesis.

Types of vegetative body of algae. Among the algae there are microscopically small and multi-meter (up to 60 meters) plants. Single-celled algae can have flagella and use them to move (Chlamydomonas) or be immobile (Chlorella). Colonial algae can also be mobile (volvox) or immobile (nostoc). Multicellular algae evolved from filamentous forms, since only filamentous algae have the characteristics of a multicellular organism:

1. cells in a filament are connected to each other by plasmodesmata;

2. differentiation of cells by function is observed;

3. threads have unlimited growth.

Multicellular algae are filamentous (spirogyra, ulotrix, anabena), parenchymatous (kelp, fucus).

The structure of an algal cell. Among the algae there are representatives of prokaryotes (blue-green algae, some green algae), mesokaryotes (dinophyte algae), but mostly algae are eukaryotes. Algal cells can be mononuclear or multinucleated, and contain up to several dozen nuclei.

The integument of the algal cell can be represented by a pectin (Chlamydomonas) or cellulose membrane (Chlorella). Some algae do not have additional covers and their cells are covered with a single plasmalemma, others impregnate their shells with lime, iron salts, silica or form silica shells and houses around the cell. The most progressive in evolutionary terms are cellulose shells, as they allowed some representatives of green algae to give rise to the ancestors of higher plants.

Algae cells contain plastids - chloroplasts or chromatophores. The term chromotophore in the scientific sense is obsolete. Despite the fact that algae plastids are colored in a wide variety of ways, in modern scientific terminology they are usually called chloroplasts, since they are functionally similar to the plastids of higher plants. Photosynthesis in plastids of both higher and lower plants proceeds according to the so-called plant type (in contrast to bacterial photosynthesis, characteristic of photobacteria). Chloroplasts can have a wide variety of shapes and sizes - cup-shaped, ribbon-shaped, lamellar, spiral-shaped, stellate, etc. The number of chloroplasts can also vary from one to several. Most algae have one large chloroplast per cell. The evolution of chloroplasts followed the path of decreasing their size and increasing their number, so higher plants have many small disc-shaped chloroplasts in their cells. The color of chloroplasts depends on the set of pigments and can be green, yellow, brown, blue-green, red, black, etc. Among the pigments contained in chloroplasts, one can distinguish the main pigments of photosynthesis - chlorophylls (green); auxiliary pigments of photosynthesis - carotenoids (yellow, red, brown); as well as additional pigments characteristic only of algae - phycobilins (blue, red). In different combinations, these pigments give a variety of algae colors.

The importance of algae in nature

· Historical meaning. The first photosynthetic organisms on our planet were blue-green algae. It was these organisms that created the oxygen atmosphere and the ozone screen, thanks to which the further development of all life on Earth became possible. Fossil remains of algae were found in Archean rocks of South Africa and are 3.2 billion years old.

· Maintaining the oxygen balance of the atmosphere. Currently, algae, releasing huge amounts of oxygen during photosynthesis, enrich the Earth’s atmosphere with it. Suffice it to recall that water covers 2/3 of the planet’s surface and contains plant plankton in the upper layer. These planktonic algae release the bulk of oxygen into the atmosphere and are therefore called the “lungs of the planet.” The O2 content in the uppermost layer of water can be 2-3 times higher than in the air.

· Powerful geological factor. Algae take part in the formation of limestone rocks (ancient blue-green algae), coral reefs (red algae), and chalk rocks (golden algae).

· Algae are the first link in the food chain of small aquatic animals (cyclops, daphnia and other invertebrates), as well as fish (silver carp, grass carp).

· Algae thickets play an important role in the creation of special aquatic biocenoses.

· Soil algae increase soil fertility due to their ability to fix nitrogen. Algae can provide up to 15% of the nitrogen needs of higher plants.

The importance of algae in industry and human economic activity

· Excessive development of algae, the so-called “blooming” of water, causes undesirable consequences and causes damage. Developing in a huge mass, algae clog and render various underwater structures unusable. The “blooming” of water gives it an unpleasant taste and smell, making it unsuitable for use for drinking and household purposes. The waste products of algae, accumulating in large quantities, lead to the death of aquatic invertebrates and fish.

· Seaweed serves as fertilizer and is used to feed livestock.

· Some algae are used for human food (chlorella, spirulina, nostoc, kelp). For example, the single-celled algae Chlorella has a high growth and reproduction rate. It is superior to wheat in nutritional value and protein content and can be used as food, to obtain vitamins and biologically active substances.

· In the pharmaceutical industry, algae serve as a source of iodine and? - carotene. Gelatinous substances are extracted from seaweed: agar-agar (from red algae) and alginate (from brown algae). These substances are colorless, tasteless and odorless. They are used in the microbiological industry for growing microorganisms, in food canning and in the production of low-fat creams (food and cosmetic), as well as fillers in the production of paints, beer, ice cream, tablets, capsules, photoimulsions and artificial fibers.

· Fossil diatoms serve as an abrasive material and are used in the manufacture of toothpastes and when grinding lenses.

Variety of algae

Algae is found almost everywhere where sufficient light penetrates.

1. Aquatic habitats

Algae inhabit fresh water bodies - rivers, lakes, ponds, swamps, as well as small temporary reservoirs - puddles, ditches, etc. The seas and oceans are inhabited by seaweeds, many of which reach large sizes. Along sea coasts, the richest vegetation is found in the coastal zone, especially at the level that is exposed at low tide. In other salt water bodies (salt lakes), where the salinity of the water is very high, algae live that have adapted to such living conditions. Some algae remain suspended in the upper layers of water all the time and, together with small animals, form plankton. Other algae live in the bottom mud or attach to underwater objects (rocks, piles, etc.), these algae form benthos.

Hot springs with water temperatures up to + 85°C are home to some types of blue-green algae that can exist at such temperatures.

2. Aquatic habitats

Soil algae develop abundantly in the upper layers of the soil (even in deserts). They actively participate in soil formation processes, thanks to their ability to fix atmospheric nitrogen. Algae develop in the form of green deposits on tree bark, fences, and drains. Snow and ice algae are the main plants of Antarctica, developing in masses they are able to color the snow green and red.

The inhabitants of the seas and oceans are mainly multicellular forms of large, sometimes gigantic sizes. Thickets of seaweed form unique underwater forests and meadows. Among the algae there are both attached forms and free-floating ones. Attachment to the ground is carried out using rhizoids, special suction cups or soles.

The uniqueness of red and brown seaweed lies in the content of special pigments, which determines the color. The water column absorbs orange-red rays, allowing blue-green rays to pass through, which can only be used with red-brown pigments. Therefore, closer to the surface, algae that are purely green in color usually live, and at a depth (up to 200 m) they are replaced by red and brown ones.

Characteristics of blue-green algae

Blue-green algae are widespread in all living environments and can exist in almost any conditions: at a temperature of -83°C in Antarctica and +85°C in hot springs. This resistance of blue-green algae cells to unfavorable environmental factors is due to the following structural features of blue-green algae cells:

1. Blue-green algae are prokaryotes.

2. There are about 30 pigments in cells, this contributes to the process of photosynthesis under extreme conditions.

3. Cells have thick multilayer walls, often covered with a mucous sheath that performs a protective function.

4. In the cells of blue-green algae, gas vacuoles filled with a mixture of gases are often found, this allows them to always be in the best conditions for photosynthesis, changing their position in the water column.

5. Many types of blue-green algae can fix atmospheric nitrogen, due to this they have food independence. This allows them to colonize uninhabited (without soil) rocks. Blue-green algae are the first to colonize lifeless habitats - lava flows, volcanic islands.

Representatives of blue-green algae are: gleocapsa, anabena, nostoc, spirulina, microcystis, merismopedia, etc.

Diversity of red algae species

In most cases, red algae, or as they are also called, purple algae, are inhabitants of the sea. They attach to various substrates (stones, shells, thalli of other algae) and, together with brown algae, constitute the largest group of marine benthos plants. Many scarlet fish live at great depths. Deep-sea forms are distinguished by a particularly bright red or crimson color.

Red algae are very diverse in their external structure. These are thread-like, cord-like, lamellar, crust-like, bushy and other forms. Most range in size from a few centimeters to 1 m or more.

In some red algae, calcium and magnesium carbonate are deposited in the cell membrane. These algae take part in the formation of coral reefs.
etc.................

It is impossible to overestimate the importance of algae in nature and human life. Thanks to the processes of photosynthesis, they are the main producers of huge amounts of organic substances in fresh and salt water bodies. Special attention is paid to the fact that algae intensively produce oxygen in the water, which is so necessary for river and sea inhabitants. Man has long appreciated these plants and found use for them in many

The importance of algae in nature and human life

Perhaps the most important function that absolutely all types of algae perform is the absorption of carbon dioxide from water. In exchange, they release oxygen, without which it is impossible to imagine the life of modern plants and animals. No less important is the participation of algae in the cycle of substances on the planet. Its cyclical nature has allowed all types of living beings to exist on earth for thousands of years. In addition, algae are the main source of organic substances in water bodies, which are an excellent food source. A huge number of animals depend on it. The evolutionary significance of algae is no less important. They significantly influenced not only the Earth, but also the formation of its relief. In addition, these plant organisms (both unicellular and multicellular) play an important role in the self-purification of rivers, lakes and ponds, as well as wastewater. Algae, especially their single-celled representatives, are an excellent indicator of salinity and pollution of a reservoir. But they live not only in water, but also in soil. Participating in the cycle of silicon and calcium, they actively enrich the earth with these components.

The importance of algae in agriculture

The enormous importance of algae in nature and human life is explained by their ability to produce organic matter. Therefore, they are widely used in the perfume, food, and pharmaceutical industries. But even more of them are used in agriculture. In developed countries, fertilizers are made from algae. If you spray seedlings of tomatoes, peppers, and eggplants with them, they will not only grow faster, but also produce a large harvest. In addition to vegetable growing, algae has also penetrated into livestock farming. Cows, geese, chickens, and ducks become more productive with a particularly balanced diet. Organic components of algae are introduced into the food of farm animals.

The importance of algae in the food industry

Every year, on all continents of the planet, people eat several billion tons of processed algae. First of all, we are talking about seaweed. It contains a huge amount of nutrients and, importantly, useful substances. These are iodine compounds and calcium, which is necessary for normal metabolism. and human life is simply enormous. Cultivation of marine and freshwater crops gives very encouraging results. They are increasingly used in the food industry. For example, Japanese cuisine uses seaweed flour when baking bread. And this is the main product on the table in every family. Algae is added to puddings, cakes and even ice cream. Recently, their use in conservation has been no less relevant. In many countries, more and more cafes are opening every year where you can order various dishes made exclusively from seaweed.

Unicellular algae and their significance in astronautics

Oddly enough, it is the simple single-celled algae Chlorella that plays a huge role in modern astronautics. It is capable of producing large amounts of oxygen. In this, almost all types of plants are inferior to it. An important fact is that it has microscopic dimensions, which means it will not take up much space. It has a short growing season and a very high reproduction rate. All the resulting chlorella biomass can be used at orbital stations not only for the production of oxygen, but also as food. Its nutritional qualities are truly impressive. The protein content of chlorella is at least 50 percent of the dry weight. In addition, this algae contains amino acids and vitamins necessary for human life. All this makes the use of chlorella in space flights very promising.

Application of algae in microbiology

The diversity and importance of algae is great. They have even found their application in microbiology. The substance agar-agar is produced from brown ones. It can harden at room temperature and turn into jelly. It was this property that became decisive in the choice between gelatin and agar in the production of nutrient media for the cultivation of microorganisms. This substance has good nutritional properties and does not melt under thermostat conditions. Therefore, currently all artificial ones are prepared on the basis of agar.

Using algae for wastewater treatment

Recently, the importance of algae in human life in the domestic sphere has increased. They are cultivated in industrial wastewater in order to activate self-purification processes. In the future, excess organic matter will be used to produce methane, which is planned to be used in agricultural and industrial production. Chlamydomonas can best deal with contamination. It is able to select organic substances from water, purifying it.

As part of the implementation of new educational standards at the secondary level, in 5th grade biology lessons, a systemic activity-based approach to learning is actively implemented, using problem-based learning technology, ICT technologies, etc. This master class can be used as a lesson in updating knowledge or a lesson to consolidate knowledge.

The purpose of the lesson: study the structure of multicellular algae and their diversity, as well as their significance for humans and in nature.

Lesson objectives:

· introduce students to the structural features of multicellular algae, their significance in nature and human life;

· continue to develop the ability to work with a textbook;

· activate and integrate knowledge in related disciplines.

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Topic: “Diversity of algae and their importance in nature and human life”

“A vast ocean of the unknown surrounds us. And the more we know, the more mysteries nature asks us,” these words belong to scientist V.A. Obruchev.

The purpose of the lesson: study the structure of multicellular algae and their diversity, as well as their significance for humans and in nature.

Tasks:

• introduce students to the structural features of multicellular algae, their significance in nature and human life;
• continue to develop the ability to work with a textbook;
• activate and integrate knowledge in related disciplines.

Planned learning outcomes

Subject: Students have an idea of ​​multicellular algae as representatives of lower plants and their characteristic features.

Metasubject: The ability to work with textbook text and illustrations develops.

Personal: elements of communicative competence are formed in communication and cooperation with classmates in the process of educational activities.

Basic concepts of the lesson:lower plants, higher plants, algae: green, brown, red, thallus, rhizoids, chromatophore,

Student activities:working with textbook text and illustrations, collaborating with classmates during discussions, working with flashcards.

Equipment: ICT personal computer, interactive whiteboard, multimedia film projector, presentation, tables with images of algae, herbarium, seaweed, flashcards, a jar of seaweed salad, ice cream, a piece of leather, a jar of paint, agar-agar, iodine.

During the classes:

Teacher: - Hello, dear guys! I'm glad you came to class today in a good mood.They say a smile is the kiss of the soul. Let's look at each other and smile. Take your seats. I have no doubt that today you will work together and actively in class.

Please note that on your desks there are individual assessment sheets in which you will complete tasks today and grade yourself, sign them.

1. Check of knowledge:work in individual student cards.

Teacher:

Mystery: There are hundred-meter snakes,
Green, purple,
There are brown and burgundy ones.
And to the captain at sea
They cause great grief.
(Seaweed)

Why are algae classified as lower plants, please explain?

What science studies algae?

Why are algae called “the oldest”?

Task No. 1. Guys, select from the proposed list the characteristics characteristic of plants. For every correct answer 1 point.

1. Found everywhere.
2. Move actively
3. motionless
4. They absorb carbon dioxide and release oxygen, purifying the air.
5. They feed by photosynthesis.
6. They feed on ready-made organic matter.
7. There are lower and higher.
8. The body may consist of a single cell or be multicellular.
9. The cell is covered with a cellulose membrane.
10. The cytoplasm contains a vacuole with cell sap.

(Correct: 1, 3, 4, 5, 7, 8, 9, 10) Max-8 points

Task No. 2. Max – 5 points

1. The science of algae is called ………(Algology)
2. …………. They live not only in water, but also on land. (Seaweed)
3. Multicellular algae attach to the substrate using - .....(rhizoids)
4. The body of the algae is called……..(thallus).
5. The method of nutrition of algae is ……….(photosynthesis).

(Correct answers: algology, algae, rhizoids, photosynthesis, thallus)

Task No. 3 . Look at the picture and find the algae on it. Why do you consider this plant to be an algae? (2 points for a complete correct answer, 1 point for a partial answer)

1. Learning new material:

1. Updating knowledge.

Problem: On the teacher's desk: a jar of seaweed salad, ice cream, a piece of leather, a jar of paint, herbarium specimens of algae.

Question: What can unite all these items? (students express their guesses, but the teacher suggests returning to the answer to the question at the end of the lesson?

So, the topic of our lesson: “The diversity of algae and their importance in nature and in human life.”

2. Classification of algae:

(1 point)

TEACHER: - Among algae there are unicellular, colonial and multicellular forms. The body of multicellular algae has no standing roots, stems or leaves and is calledthallus (thallus), are attached to the substrate using rhizoids . Unicellular algae are microscopic organisms, and the size of multicellular algae can reach tens of meters (macrocystis 150-300 m). (we write down the diagram (a) on the board, and the students in their notebooks).

Now we are working in groups (the class is pre-divided into three groups, curators are assigned). First group - pp. 95-97 while reading and working with pictures, we supplement the table with examples of representatives of green algae. Second group - p.98 while reading, supplements with examples of representatives of brown algae. Third group – pp. 98-99, while reading and working with pictures, supplements the diagram with examples of green, brown and red algae. 3-4 minutes to work.

Plant Kingdom

Inferior Superior

Seaweed

Unicellular Multicellular

Greens

(chlamydomonas) Green Brown Red

Chlorella (Ulva) (Lainaria) (Porphyra)

(5 points)

The group's work is checked on the interactive whiteboard while drawing up the diagram.

DYNAMIC PAUSE (1.5 minutes)

3. Diversity of multicellular green algae.

Students listen to the speakers and fill out the section “What do I know about the importance of algae?” in the table.

Teacher: Green algae are unicellular and multicellular, forming filaments, spherical colonies, leaf-like structures, etc. One well-known genus is Pleurococcus, a single-celled algae that produces green growths often seen on the bark of trees. The largest green algae is sea lettuce (Ulva), a leaf-shaped macrophyte. In the process of life, cells divide and the algae grows. In a favorable period, it reproduces asexually, and in an unfavorable period, it reproduces sexually, i.e. with the help of gametes.

STUDENT 1: Chlorella is a veteran of space biology: during space flights, experiments were conducted to purify the air and process organic residues in the compartments of spaceships. Among the mobile green algae, Volvox is known, which was discovered by Anthony Van Leeuwenhoek and compared it with the Universe.

Teacher: Thus, off the coast of the Gulf of Mexico, the berry-bearing sargassum dominates. During a storm, raging waves carry it away and transfer it to the Gulf Stream, which carries it far into the ocean. The long drift ends near the Azores, where plants accumulate in a calm sea. Sailors were afraid to enter the waters of this sea. What kind of sea are we talking about and what algae form it?

4. Brown and red seaweed (student report). STUDENT 2: Brown algae- in this group there are no single-celled organisms; they all form thalli - from thin threads from one row of cells to huge (up to 50 m!) stripes and ribbons of brown and bluish-brown color. Brown algae are immobile, attached forms. Reproduction is vegetative, asexual and sexual. Brown algae live primarily in the sea, with the exception of a few freshwater species. Almost all brown algae grow attached to the seabed, rocks, and other algae. Only the sargassum of one of the areas of the Atlantic, surrounded by a ring current, floats freely on the surface, supported by small berry-shaped floats - bubbles.

STUDENT 3: Laminaria algae, known in everyday life as seaweed, is of great benefit to people. Its thallus reaches a length of several meters. In many countries of Europe, Asia and America, kelp is used as food, livestock feed, and for industrial processing. Valuable drugs are obtained from them - alginate, mannitol, laminarin. Laminaria has been used especially for a long time and widely in Japan and China. It is used to make vegetable caviar and purees, salads, canned food and even... candy. Alginic acid salts– alginates can bind 300 volumes of water per unit volume, forming a viscous solution. Alginates are required in the production of ice cream, fruit juices, canned food, plastics, varnishes and paints; they are needed in the textile industry, printing, medicine, perfumery and even in foundry. No less important is another product obtained from brown algae - hexahydric alcohol mannitol. It is needed both in the treatment of diabetes and in the manufacture of leather, paper, varnishes, and paints. They also make strong explosives from it. In the seas of the southern hemisphere, the world's largest algae is found - the famous pear-bearing macrocystis. Its total length (according to scientists) reaches from 150 to 300 m and more.

STUDENT 4: Red algae are multicellular, very rarely unicellular, of complex structure, most of them are marine leaf-shaped, bushy or crustaceous macrophytes that live below the low tide line. Red algae are benthic plants and are not found in plankton. They penetrate to great depths (up to 200 m). The reason for the shade tolerance of red algae is their photosynthetic pigments. The color of algae depends on the depth of their habitat. In shallow water they are yellow-green or bluish in color, deeper they turn pink, then turn red. The most intense red color is at a depth of more than 50 m. But this is how they look when pulled to the surface in direct sunlight. Divers at the bottom see them as black: after all, the red rays are absorbed by the first meters of water. Photosynthesis of red algae occurs in blue rays, which penetrate most deeply into the water. The methods of reproduction of red algae are varied: division of the thallus, spores (without flagella). The sexual process is very complex.

STUDENT 5: One of the algae living in the North Sea, chondrius, has long been used in dry form as a medicine for respiratory diseases. Agar-agar is obtained from other scarlet plants, which is used in all microbiological laboratories in the world to obtain pure cultures of microbes. However, they cannot do without it in the food industry, and even in the production of film. Confectioners and bakers add a small amount of agar-agar to the dough so that cakes, biscuits, and bread do not go stale longer. In some red algae, the thalli are heavily saturated with lime, causing them to look like corals. Many coral reefs are largely formed by these dead algae. Unlike corals, they go far to the north, forming red-pink crusts on the rocky bottom in the Barents and White Seas in places with strong currents.

Teacher: Guys, rate your work on a five-point scale. When assessing, take into account: how interesting the educational material was for you; how often were you distracted? was everything clear to you; Did you actively participate at this stage of the lesson?

5. The importance of algae in nature and human life (6 min.)

Students work independently with the text of the textbook, pp. 99-101, and take notes in their notebooks.

Meaning of algae:

After the specified time, the teacher provides the correct answers on the board(Table in notebook).Correct mistakes and give themselves points for this task - max – 5 points.

1. Consolidation-reflection.

1. "Black box". Each group is given Black Boxes containing mysterious algae-related objects. Students read the task and guess what is in the box. For a correctly guessed riddle, a 1 point.

1 box (first group)–

Here's the medicine. Do not be afraid:

For health and beauty

Children smear it on their knees,

Elbows, cheeks and noses. (IODINE)

2 drawer (second group)–

Look! Under the water

A whole garden has grown.

He will feed you and me,

It will end up in the salad. (seaweed salad, jar of lettuce)

3 drawer (third group) -

Separately, I’m not so tasty,
But everyone needs food. (SALT)

1. “You - for me, I - for you.”Work in pairs. Students are asked to make up two questions and ask each other. The first question is about the structure of algae. The second question is about the importance of algae. Max. 2 points.

Teacher: - Guys, today in the lesson we got acquainted with the diversity of algae, their significance in nature and human life, and I think that now you are ready to answer the question asked at the beginning of the lesson, what can unite all the objects on my table?(Answer: they are all made either from algae or using algae products)

Reflection:

What did you like about today's lesson?

What new did you learn?

What didn't you understand?

Summarizing:points are calculated

Max-30 points.

30-26 – score 5

25-21- score 4

20-16 score 3

Below 16, guys, don’t despair, study the material at home and consolidate it? after the paragraph.

IV.Homework.P.18 read, vocabulary work. Creative work: message or abstract.

Literature:

1. http://biolicey2vrn.ru/index/mnogoobrazie_vodoroslej/0-92
2. Biology. Bacteria. Mushrooms. Plants. 5th grade: textbook. For general education Institutions / V.V. Beekeeper. – M.: Bustard, 2012. – 141, (3) p.
3. Biology: Diagnostic works for the textbook by V. Pasechnik “Biology. Bacteria, fungi, plants. 5th grade”/ V.V. Beekeeper. – M.: Bustard, 2015. – 92 p.
4. Secrets of nature: A manual for students in grades 5-7/Compiled by T.S. Sukhova, V.I. Stroganov - M.: Venta-Graf, 2001. - 208 p.: ill. (Behind the pages of the textbook).

Preview:

Scorecard

Student of class 5B____________________

Task No. 1 .Guys, select from the proposed list the characteristics characteristic of plants. For every correct answer1 point. Max. 8 points.

Write down the numbers of signs_______________________________ points

Task No. 2. Fill in the missing word according to its meaning. For each correct answer - 1 point, Max – 5 points

1. The science of algae is called - ………
2. …………. …..they live not only in water, but also on land.
3. Multicellular algae attach to the substrate using -………..
4. The body of algae is called -………………
5. The method of feeding algae is ……………...

Points

Task No. 3 . Look at the picture and find the algae on it. Why do you consider this plant to be an algae? (2 points for a complete correct answer, 1 point for a partial answer)

Points

Task No. 4. Algae classification:

Examine the picture and identify differences in the structure of the plants depicted on it. What two groups of “Algae” can be distinguished based on this picture?(1 point)

Points

Task No. 5. Draw up a classification scheme for Algae, supplement it with examples.

About 20 thousand species of green algae are distributed mainly in fresh water bodies and on humid areas of land. Among the pigments found in chromatophores in cells, chlorophyll predominates, which gives them a green color. The following types of green algae are widespread: chlamydomonas, chlorella, volvox, spirogyra, ulotrix. The unicellular algae Chlamydomonas and Chlorella have a cellulose membrane, cytoplasm, nucleus, and cup-shaped chromatophore, but there are significant differences between them.

Chlamydomonas actively moves, has flagella, a red light-sensitive eye, there are pulsating vacuoles, sexual process with the help of gametes, non-sexual reproduction with the help of gametes, spores live in small fresh water bodies.

Chlorella motionless, no flagella, no photosensitive red eye, pulsating vacuoles, no sexual process, no asexual reproduction by immobile spores, lives in fresh and salt water bodies, on damp soil on land.

Volvox lives in fresh water bodies, it is a colonial algae. It looks like small (up to 2 mm) balls. Volvox colonies consist of a large number of cells (up to 20 thousand), each of which is similar to Chlamydomonas, inside the colony is filled with jelly. Volvox reproduces both sexually and asexually.

Spirogyra and Ulotrix are filamentous algae, multicellular.

Ulotrix- a freshwater algae whose cells are arranged in one row and have the ability to continuously divide. Ulotrix reproduces vegetatively by fragments of filament, asexually - with the help of chotiridgutic gametes. Sexual reproduction occurs with the participation of biflagellate gametes.

Spirogyra- a filamentous algae that forms the bulk of the slippery mud in ponds. The cell has a membrane covered with mucus, a large nucleus with a nucleolus “suspended” on cytoplasmic strands, a ribbon-like spirally twisted chromatophore and a large vacuole. Vegetative propagation of Spirogyra occurs in snatches of its filaments. There is no asexual reproduction. The sexual process - conjugation - is the fusion of the contents of ordinary vegetative cells, and not special gametes. Sexual reproduction occurs when living conditions deteriorate. Conjugation steps:

1. two threads are arranged in parallel;
2. opposite cells form outgrowths towards each other, like a bridge;
3. the shells at the ends of the outgrowths dissolve;
4. the contents of one cell flow into the cell opposite and merge with its contents, resulting in the formation of a zygote.

The zygote becomes covered with a thick shell and goes into a dormant state; in this state, it can withstand freezing and drying well. Under favorable conditions, the zygote nucleus is divided into 4; subsequently, only one nucleus grows into filamentous algae - spirogyra.

Diatoms, brown and red algae

Diatoms are microscopic unicellular or colonial; there are about 15 thousand species. They live in salt and fresh water bodies, on the ground. The structure of the shell of diatoms of the genus: they have a shell made of silicon compounds. It consists of two halves that fit on top of each other like a lid on a box. The shells have gaps through which the exchange of substances with the environment takes place. The chromatophores of these algae are light yellow in color, because, in addition to chlorophyll, they also have brown pigments.

Brown algae. The department includes mainly marine multicellular algae; they number about 15,000 species. These algae store a special substance - laminarin. Brown algae are colored yellow-brown - in their cells, in addition to chlorophyll, there are brown and yellow pigments. In size they range from several centimeters to tens of meters (macrocystis has a length of 60 m). Laminaria, or seaweed, is one of the brownest algae of the predominantly cold seas of the World Ocean. It has a rhizoidal part of the thallus, which is attached to the bottom surface, an elongated “stovburets” and a leaf-shaped part of a lamellar shape. Laminaria reproduces asexually with the help of flagellated zoospores and sexually with the help of gametes. Laminaria is characterized by alternation of sexual and non-sexual generations in the life cycle, with a clear advantage of the non-sexual generation (sporophyte, from the gr. Spora and Phyton - plant), that is, plants that form sporulation organs. Sargassum is a genus of brown algae, various species of which either grow on the bottom of shallow seas or float passively at the surface of the water, forming large accumulations (Sargasso Sea south of Bermuda). The brown algae Cystoseira grows in the Black Sea. Red algae (purple algae). Like brown algae, they are exclusively multicellular organisms. Purple fish live mainly in warm seas. In total, about 4000 species are known.

Red algae have chlorophyll as well as red, bluish and yellow pigments. Their combination in different species determines the different colors of these algae. Red pigments allow them to capture weak light at a depth of 200 m. They are the only algae that live at such depths in the seas. Red algae store purple starch, a substance similar in chemical structure to glycogen (a compound stored in the body of animals). Purple plants reproduce by vegetative, asexual and sexual methods. In their life cycle, there is an alternation of generations and a complete absence of mobile stages (no flagella). This puts red algae in a special place among algae.