Seaweed- these are lower chlorophyll-containing plants that are not divided into stems, roots and leaves. A heterogeneous ecological group of predominantly photoautotrophic unicellular, colonial or multicellular organisms, usually living in an aquatic environment.

general characteristics algae:

• The body is not divided into organs (in multicellular organisms); lack of clear differentiation of the body (called thallus, or thallus).
• No specialized fabrics.
• Cells contain chlorophyll. Photosynthesis occurs. Photoautotrophic nutrition.
• Reproduction: asexual, sexual and vegetative.
• Distribution in water: suspended (plankton); at the water-air boundary (neuston); at the bottom or at considerable depth (benthos); on underwater rocks (periphyton).

Algae include a different number (depending on the classification) of divisions eukaryotes, many of which are not related by common origin. Also often referred to as algae blue green algae or cyanobacteria , which are prokaryotes . Traditionally, algae are classified as plants.

Department of green algae.

Green algae They are divided into unicellular and multicellular forms and contain chlorophyll. They have all types of asexual and sexual reproduction. Greens in. found in salt and fresh water bodies, in soil, on tree bark, on stones and rocks. This department has up to 20 thousand species and includes five classes:

• The hair class is the most primitive unicellular species. with flagella. Some of their species are a colony.
• Class protococcal - unicellular and multicellular flagellated forms
• Ulothrix class - have a filamentous or lamellar structure of the thallus.
• Fire class - their structure resembles higher plants - horsetails.
• Siphon class - outwardly similar to others in. or higher plants, consist of one multinucleate cell, reaching sizes up to 1 m.

Single-celled green freshwater algae- chlamydomonas. It has an oval or round body shape, with two flagella at the elongated anterior end. The chromatophore is cup-shaped, with a pyrenoid containing starch grains. At the front of the cell, the red eye is a light-sensitive organ. There is one nucleus, with a small nucleolus. Two pulsating vacuoles are displaced towards the anterior end of the cell. Chlamydomonas feeds autotrophically, but in the absence of light it can switch to heterotrophic nutrition if organic substances are present in the water. Reproduces asexually and sexually. During asexual reproduction, the contents of the cell ( sporophyte) is divided into 4 parts and 4 haploid zoospores are formed. With the onset of cold weather, 2 zoospores fuse, forming a diploid zygotospore. In the spring, it divides by mitosis, again forming haploid cells.

Spirogyra- freshwater green multicellular filamentous algae. The filaments are composed of one row of mononuclear cylindrical cells with spiral-shaped chloroplasts and pyrenoids. The growth of the filament in length occurs asexually due to transverse cell division. Reproduces by parts of a thread or sexually. The sexual process is called conjugation.

Department of brown algae

Multicellular algae. Counts approx. 1500 species. They have a yellowish-brown color due to a large number of yellow and brown pigments. Their size and shape are different. There are thread-like, crust-like, spherical, lamellar and bush-like plants. The thalli (bodies) of many species contain gas bubbles that hold the. in a vertical position. The vegetative body is divided into a sole or rhizoids, which serve as organs of attachment, and into a simple or dissected plate connected to the sole by a petiole. The pigments that give them their brown color are concentrated only in the surface layers of the cells; the inner cells of the thaloma are colorless. This indicates the differentiation of cells according to functions: photosymthetic and extinction. Brown algae do not have a true conducting system, however, in the center of the thallus there are tissues through which assimilation products move. Absorption of minerals occurs over the entire surface of the thallus.

Brown algae have all forms of reproduction: vegetative (with random separation of parts of the thallus), spore, sexual (three forms: isogamous, heterogamous and monogamous).

Department of red algae (purple algae)

They are usually found at great depths in warm seas. They count approx. 4000 species. They have a dissected thallus and are attached to the substrate by a rhizoid or sole. In addition to the usual chlorophylls and carotenoids, scarlet plastids contain phycobilins. Another feature of them is the complex sexual process. Gametes and spores of red algae lack flagella and are immobile. Fertilization occurs through the passive transfer of male germ cells to the female reproductive organ.

The meaning of algae

Seaweed- primary producers with high productivity. Most of the food chains of the seas, oceans and fresh water bodies begin with them. Unicellular c. are the main component of phytoplankton, which serves as food for many species of aquatic animals. V. enrich the atmosphere with oxygen.

Many valuable products are obtained from algae. For example, the polysaccharides agar-agar and carrageen are obtained from red algae (used to produce jelly, in cosmetics and as food additives); Alginic acids are obtained from brown algae (used as hardeners, gelling agents in the food and cosmetics industries, for the manufacture of paints and packs).

Table "Algae"

Lesson summary "Algae". Next topic:

This is a summary of the topic "Lower plants. Seaweed". Choose what to do next:

• Go to next summary:

According to the modern system, the plant world is divided into two subkingdoms: lower and higher plants. The lower plants, which arose about 2 billion years ago, include the most simply organized representatives of the plant world.

Lesson content:

1. Algae are lower plants. General characteristics.

According to the modern system, the plant world is divided into two subkingdoms: lower and higher plants.

To lower plants , which arose about 2 billion years ago, are the most simply organized representatives of the plant world.

A characteristic feature of this group of organisms is that:

• their the body is not divided into vegetative organs(root, stem, leaf) and represented by a thallus, or thallus,
• they lack tissue
• organs of sexual and asexual reproduction are usually unicellular.

Lower plants - algae and lichens - widely distributed in nature and play an extremely important role in the general cycle of substances.

As their name suggests, they are plants that live in water.

However, this is not quite true. Algae are able to live and reproduce in conditions that at first glance seem completely unsuitable for habitation. Some algae have reached land, and there are types of algae that live as symbionts inside the body of some animals and plants.

Do not forget that there are also higher plants, for example, water lilies or lotuses, that live in water, but they do not belong to algae.

To summarize, we can say that the term “algae” is convenient in itself, but its use in taxonomy introduces unnecessary complications.

Habitats. Fresh and salty bodies of water, tree bark, wet areas of soil.

The bulk of them live in seas, oceans, rivers, streams, swamps - wherever there is water. However, many species are also found on the soil surface, on rocks, in snow, hot springs, salty reservoirs, where the salt concentration reaches 300 grams per liter of water, and even... in the hair of sloths living in the rainforests of South America, and inside the hair of polar bears living in zoos. Polar bears have hollow hair inside, and Chlorella vulgaris settles there. When developed en masse, algae “color” animals green. However, the life of all these plants is connected with water; they can easily tolerate drying out and freezing, but as soon as a sufficient amount of moisture appears, the surface of the objects becomes covered with a green coating.

There are types of algae living as symbionts inside the body of some animals and plants. The well-known lichen is an example of the symbiosis of a fungus and algae.

Ground, or, as they are also called, aerial algae, can be found on tree trunks, rocks, roofs of houses, fences. These algae live wherever there is even the slightest constant moisture from rain, fog, spray from waterfalls, and dew. During dry periods, the algae dry out so much that they crumble easily. Growing in open areas, they get very hot in the sun during the day, cool down at night, and freeze in winter.

Cold-loving algae often settle on glaciers, snowfields, and ice.. Under these conditions, they sometimes reproduce so intensively that they paint the surface of ice and snow in a wide variety of colors - red, crimson, green, blue, cyan, violet, brown and even... black - depending on the predominance of certain cold-loving algae.

Algae also develop in lakes where the salinity is so high that salt falls out of the saturated solution. Only a few algae can tolerate very high salinity.

A significant part of the algae lives in the soil. The largest number of them are found on the surface of the soil and in its uppermost layer, where sunlight penetrates. Here they live by photosynthesis. With depth, their numbers and species diversity sharply decrease. The greatest depth at which viable algae was found was 2 meters. Scientists believe that they are carried there by water or soil animals. In such unfavorable conditions, algae are able to switch to feeding on dissolved organic substances.

Number of species. More than 4 known 0 thousand species of algae, which are combined into two sub-kingdoms - Purple and True algae.

Sub-kingdom of Bagryanka

DEPARTMENTS:

• Red algae

Subkingdom Real algae

They are divided into several separate departments, which differ from each other in a number of such important characteristics as:

• thallus structure,
• a set of photosynthetic pigments and reserve nutrients,
• characteristics of reproduction and development cycles,
• habitat

DEPARTMENTS:

• Charovaya algae
• golden algae
• Diatoms
• Brown algae

2. Unicellular algae. Features of structure and life activity.

Green algae are algae that are green in color. Unicellular algae (Chlamydomonas, Chlorella) - one cell covered with a membrane, inside is a nucleus carrying hereditary information, cytoplasm (a viscous semi-liquid mass that connects all organelles of the cell) and a chromatophore with chlorophyll.

During the “blooming” of small puddles or ponds, the most common unicellular green algae found in the water is chlamydomonas . Translated from Greek, “chlamydomonas” means “the simplest organism covered with clothing” - a membrane. Chlamydomonas is visible only under a microscope. It moves in water with the help of two flagella located at the anterior, narrower end of the cell. Breathes oxygen dissolved in water. It can absorb ready-made organic substances dissolved in water from the environment. Therefore, Chlamydomonas, together with other unicellular green algae, is used in wastewater treatment plants. Here the water is purified from harmful impurities.

Chlorella- also a unicellular green algae, widely distributed in fresh water bodies and soils. Its cells are small, spherical, and contain a green chromatophore. Chlorella multiplies very quickly and actively absorbs organic substances from the environment. Chlorella is an even smaller algae than Chlamydomonas, without contractile vacuoles and without an eye.

Cell structure . The cells of most algae do not differ significantly from typical cells of higher plants, but they have their own characteristics.

Algae cells have a cell wall consisting of cellulose and pectin substances. Many of them have additional components in their cell wall: lime, iron, alginic acid, etc.

The cytoplasm in most algae is located in a thin layer along the cell wall and surrounds a large central vacuole. In the cytoplasm, the endoplasmic reticulum, mitochondria, Golgi apparatus, ribosomes, and one or more nuclei are clearly visible.

In algal cells, organelles are especially noticeable chromatophores (chloroplasts), which, unlike the chloroplasts of higher plants, are more diverse in shape, size, number, structure, location and set of pigments. They can be cup-shaped, ribbon-shaped, lamellar, stellate, disc-shaped, etc.

Concentrated in chromatophores photosynthetic pigments: chlorophylls a, b, c, d, carotenoids (carotenes and xanthophylls), phycobilins (phycocyanin, phycoerythrin). In addition, the chromatophore matrix contains ribosomes, DNA, lipid granules and special inclusions - pyrenoids. Pyrenoids are characteristic of almost all algae and a small group of mosses. They are not only a place of accumulation of reserve nutrients, but also a zone of their synthesis.

Substances in reserve algae contain starch, oil, glycogen, volutin, water-soluble kelp polysaccharide, etc.

REPRODUCTION: Algae reproduce sexually and asexually.

Asexual reproduction carried out by special cells - spores and zoospores , which are formed in special organs or inside vegetative cells. Spores are immobile, but zoospores can move using flagella. Both are covered with a shell and are formed in large quantities. Zoospores most often do not differ from the vegetative cells from which the body of the organism is built; after a short movement, they lose their flagella and germinate into a new algae, like ordinary spores.

Usually, algae reproduce asexually in favorable conditions. When living conditions worsen(high or low temperature, accumulation of metabolic products in habitats with high population density, pollution of water bodies) they begin sexual reproduction.

Colonial algae. Volvox. Transition to multicellularity

In ponds and lakes you can find green, round organisms up to 1 mm in diameter floating in the water. This is a Volvox.

Under a microscope it can be seen that each such ball consists of many (about 1000) cells. The bulk of the ball is a semi-liquid gelatinous substance. The cells are immersed in it at the very surface, so that the flagella stick out. Thanks to the movement of the flagella, Volvox rolls in the water ("volvox" means "rolling").

Each Volvox cell looks like an independent protozoan, but together they form a colony, as they are connected to each other by cytoplasmic bridges. This explains the coordinated work of flagella throughout the colony.

When Volvox reproduces, some cells dive deep into the colony. There they divide, forming several new young colonies that emerge from the old Volvox to the outside.

3. Multicellular algae. Diversity of multicellular algae.

The body is a thallus, or thallus, covered with a cell wall made of cellulose and pectin substances, and mucus. Cytoplasm, vacuoles filled with cell sap, the cell contains one or more nuclei, and plastids, or chromatophores containing pigments.

Green algae department.

Thalluses pure green color. Cell chromatophores contain pigments chlorophyll, carotene and xanthophyll, with the green pigment quantitatively predominant over the yellow ones. The department has about 6 thousand species.

Department	Representative	Description	Habitat
Greens	Ulotrix	The filaments consist of a number of short cells. One core. Chromatophore in the form of an open ring.	Lives in marine and flowing fresh waters
		The cells are elongated, cylindrical, covered with mucus. Chromatophores in the form of spirally twisted ribbons. Forms large cotton wool-like accumulations on the surface of the water.	Distributed in fresh, standing and slow-moving waters.
	Ulva or sea lettuce	Thallus lamellar, whole, dissected or branched, length 30–150 cm, consists of 2 tightly closed layers of cells.	Most widely distributed in the seas of subtropical and temperate zones
	Nitella (flexible glitter)	The plant forms dense thickets in the water column; it is a thicket of tangled dark green glassy filaments, the latter formed by long cylindrical cells. In appearance it looks like horsetail. Often grown in aquariums. Characeous algae have formations that, in shape and functions, resemble the organs of higher plants.	Distributed in fresh water bodies of Europe, Asia, and North America.

1. Ulotrix. 2. Ulotrix thread under a microscope.

3. Codium. 4. Ulva (sea salad).

5. Spirogyra under a microscope.

Department Brown algae

Includes 1500 species (3 classes), most of which are marine organisms. Individual specimens of brown algae can reach a length of 100 m.

They form real thickets, for example, in the Sargasso Sea.

In some brown algae, such as kelp, tissue differentiation and the appearance of conductive elements are observed.

Multicellular thalli characteristic brown color(from olive green to dark brown) must fucoxanthin pigment, which absorbs a large number of blue rays that penetrate to great depths.

Thallus secretes a lot of mucus that fills the internal cavities; this prevents water loss.

Rhizoids or the basal disk attaches the algae to the ground so tightly that it is extremely difficult to tear it away from the substrate.

Many representatives of brown algae have special air bubbles, allowing floating forms to hold the thallus on the surface, and attached ones (for example, fucus) to occupy a vertical position in the water column.

Unlike green algae, many of which grow along the entire length, brown algae have an apical growth point.

Representative - kelp.

(sea kale) is an edible algae belonging to the class of brown seaweeds.

Since time immemorial, it has been used in the diet of those people who live near the sea. It was also used as a fertilizer, since kelp contains a very large set of macro- and microelements. Laminaria is especially rich in iodine, which it contains in organic form, which affects its absorption by the human body. Therefore, kelp is able to regulate the functioning of the thyroid gland.(/spoiler)

Department Red algae or purple algae

Red algae, or purple algae (Rhodophyta), have a characteristic red color due to the presence phycoerythrin pigment. In some forms the color is dark red (almost black), in others it is pinkish.

Marine (rarely freshwater) filamentous, leaf-shaped, bushy or encrusting algae with a very complex sexual process. Red algae live mainly in the seas, sometimes at great depths, which is associated with the ability of phycoerythrin to use green and blue rays for photosynthesis, which penetrate deeper than others into the water column (the maximum depth of 285 m at which red algae was found is a record for photosynthetic plants).

Some red algae live in fresh water and soil.

About 4000 species are divided into two classes. Agar-agar and other chemicals are extracted from some scarlet plants. purple used for food.

Red algae. Porphyra.

Red algae. Birth (Rhodymenia).

4. The importance of algae in nature and human life.

The widespread distribution of algae determines their enormous importance in the biosphere and human economic activity. Thanks to their ability to photosynthesize, they are the main producers of huge amounts of organic substances in water bodies, which are widely used by animals and humans.

By absorbing carbon dioxide from the water, algae saturate it with oxygen, necessary for all living organisms in water bodies. Their role is great in the biological cycle of substances, in the cyclical nature of which nature solved the problem of the long-term existence and development of life on Earth.

In the historical and geological past, algae took part in the formation of rocks and chalk rocks, limestones, reefs, special varieties of coal, a number of oil shale, and were the ancestors of plants that colonized the land.

Algae are extremely widely used in various sectors of human economic activity, including the food, pharmaceutical and perfume industries. In eastern Southeast Asia, seaweed has long been used to make soups. They are grown in estuaries on bamboo sticks stuck into the mud or on wooden frames lowered into the water of narrow bays.

Marine and water culture have begun to produce encouraging results in many countries. Japanese cuisine uses seaweed to bake bread and add it to cakes, puddings and ice cream. Even canning mushrooms is done using algae. One row of mushrooms is placed in the tubs, then one row of seaweed, etc. In many cities around the world there are specialized cafes where you can try a wide variety of seaweed dishes. In addition, seaweed has been found to contain vitamins A, B1, B2, B12, C and D, iodine, bromine, arsenic and other substances.

Algae have penetrated into agriculture and animal husbandry. Tomatoes, peppers and watermelons ripen faster and produce greater yields if they are sprayed with seaweed meal. Cows and chickens become more productive if they are fed algae concentrates.

Single-celled green chlorella produces large amounts of oxygen, accumulates organic matter using a smaller volume of suspension, has a shorter growing season, reproduces very quickly, and the entire biomass of the algae can be used as food. Its nutritional qualities are the highest in the plant world. The protein content is 50% of the dry weight, it also contains all 8 amino acids necessary for human life, and all vitamins. These abilities of chlorella make it possible to use these microalgae for air regeneration in closed biological human life support systems during long-term space flights and scuba diving.

In our country and abroad, microalgae are cultivated on municipal and industrial wastewater for the purpose of biological treatment and further use of their biomass to produce methane or for use in industry and agricultural production.

MEANING:

In nature:

• enrich the atmosphere and hydrosphere with oxygen;
• the main source of organic matter in water bodies;
• participate in self-purification of natural and waste waters;
• indicators of pollution and salinity;
• participate in the cycle of calcium and silicon in soil formation;

In human life:

The most important components of ecosystems: food, dietary products, sources of raw materials for the production of substances necessary in industrial sectors (pharmacological, paper, textile), are used as fertilizers.

Algae are plants from the sub-kingdom of the Lower Ones, living primarily in water. The body of the algae is a continuous thallus and is not divided into stem, root and leaves.

What types of algae are there?

Mainly classified by color.

Divided into:

• green;
• brown;
• red;
• diatoms.

Description of algae, life cycle, features, meaning

Green algae contain the pigment chlorophyll, which is necessary for the process of photosynthesis. An example of a single-celled green algae is Chlamydomonas.

They can also be multicellular, for example Spirogyra.

Green algae have a filamentous or lamellar (flat) body structure; the shape can be round or oval. Single-celled green algae may have flagella. Algae feed autotrophically, that is, they use light to obtain energy.

Green algae live on the surface of water bodies, within ten meters of depth. They can also be found on the bark of trees and on the surface of stones. They reproduce asexually (by fission, mitosis) and sexually (by conjugation). The largest amount of algae appears in the spring.

Brown algae are multicellular and, as a rule, have a vertical position in water due to the presence of gas bubbles in their composition. They grow at great depths. They have rhizoids, with the help of which they are attached to the components of reservoirs. Just like green ones, they have autotrophic nutrition. Consist of differentiated cells. The most famous brown algae is kelp. They reproduce by vegetative, asexual and sexual methods. Their shape is varied (for example, bush-like).

Red algae live at the greatest depths. They have a dissected body and also have rhizoids. They contain chlorophyll, red pigments phycobilins and water-insoluble carotenoids. They reproduce in a complex sexual way.

If algae do not have enough light to feed, they can switch to heterotrophic nutrition. These plants are necessary for purifying water bodies and producing oxygen. Many of them are used as human food.

Diatoms are single-celled; have a shell. This is mainly plankton. It can only be seen under a microscope.

Algae are autotrophic, photosynthetic, eukaryotic organisms. There are about 30,000 species of different algae. Algae are unicellular, multicellular and colonial.

Algae are classified as lower plants because they do not have vegetative organs (leaves, roots, buds, etc.), as well as mechanical tissue.

Most species grow in the water column, but some can live on the soil surface, on tree bark, and on rocks.

There are three main divisions of algae: Green algae, Red algae (purple algae) and Brown algae.

Algae reproduce both asexually (vegetative reproduction and spore formation) and sexually (gamete formation)

Biology lesson "Algae"

Lesson objectives:

1. To acquaint students with the features of the habitat, structure and life activity of algae, as the most simply organized representatives of the plant world;
2. Explain how algae reproduce;
3. Show the importance of algae in nature and human life.

Lesson type:

A lesson in studying and initially consolidating new knowledge.

Equipment:

Table “Algae”, presentation of the topic (multimedia support) “Algae”, individual cards, drawings of algae, recipe for algae salad.

During the classes

1. Organizational point:

Greeting students - 1 minute,(slide 1, 2) Annex 1

Preparing for the survey – 3 minutes.

2. Checking homework:

• Work on individual cards (4 people)
  – plant sizes – Fig. 30 (Appendix 3, Appendix 4)
  – plant diversity – rice 31, 32, 33 (Appendix 2)
  – work with the mini-football class(slide 3, 4, 5)
• Frontal survey. Warm-up “Terms” (1–4 people)
  – botany is…..
  – lower plants are…..
  - higher plants are...
  – thallus, or thallus – this is...
• Individual work with students(slide 6) . Work at the board. Building a classification of the plant kingdom

3. Activation of students' knowledge

Individual survey of 5 students. Questions at the end of the paragraph.

– What does botany study?

– Why were plants separated into an independent kingdom?

– What is the significance of plants in nature?

– What is the importance of plants in human life?

– Why is it necessary to protect plants?

Evaluating Student Answers

4. Learning new material (25 min)

9Write down the topic of the lesson in your notebook). Teacher's story(slide 7).

Algae are the most ancient animals on Earth. They mainly live in water, but there are species that live in damp areas of soil, tree bark and other places with high humidity.

Among algae there are unicellular and multicellular plants. Algae are lower plants. They have no roots, no stems, no leaves. Algae reproduce by simple cell division or spores.

Algae evolved from different ancestors.

1) Unicellular algae

(Working with the textbook pp. 58–67 for options 1–2).

Habitat or distribution(slide 8)

Green algae live in salt and fresh water, on land, on the surface of plants, stones or buildings, in damp, shaded places. You, obviously, observed the “blooming” of water in puddles and ponds in summer, and in strong lighting in an aquarium(slide 9) . “Blooming” water has an emerald hue. Under a microscope, a drop of water shows many single-celled green algae, which give it an emerald hue.(slide 10).

The most common type of algae found in water blooms is single-celled algae.

Chlorella. *Structure: shell, cytoplasm with a nucleus, and in the cytoplasm there is a green chromatophore(slide 11).

* Reproduction of chlorella(slide 12).

* Green unicellular algae, common in fresh water bodies and wet soils,(slide 13)

Chlamydomonas (from Greek “the simplest organism covered with a clothing-shell”(slide 14). It is pear-shaped and moves in water with the help of 2 flagella.

* The structure (p. 35 Chlamydomonas and Chlorella) is externally covered with a transparent membrane, under which there is cytoplasm with a nucleus, a red “eye” (a red light-sensitive body), a large vacuole (filled with cell sap), and two small pulsating vacuoles. Chlorophyll and other pigments are found in the chromatophore,(slide 15)

* Reproduction, (slide 16, 17)

Complete laboratory work No. 39, page 18 in your workbook.

Dynamic pause (algae movement during flow)

2) Multicellular algae

Green algae live in flowing bodies of water attached to underwater rocks and snags (ulotrix). In stagnant and slowly flowing waters, bright green stones float and settle to the bottom. They look like cotton wool and are formed by clusters of filamentous algae spirogyra. They live in the seas and oceans (ulva or sea lettuce). Charophyte algae, which have a complex structure, live in freshwater(slide 18, 19).

In multicellular representatives of green algae, the body (thallus) has the shape of threads or flat leaf-like formations. Charovaya algae have rhizoids (from the Greek “rhiza” - root and “Eidos” - species) colorless branched thread-like cells. They are used to attach them to the ground.

Brown algae. Marine plants, the external sign is the yellowish-brown color of the thalli. What is thallus? Thread-like, spherical, lamellar, bush-like. They are attached to the ground by rhizoids or the base of the thallus. Some brown algae develop groups of cells that can be called tissues(slide 20).

Laminaria, or seaweed(north, Arctic Ocean). Cystoseira (Black Sea).

Red algae or purple algae are multicellular marine plants. Rarely found in freshwater bodies. Very few are single-celled. Sizes from a few centimeters to 1 meter in length. In addition to chlorophyll, it contains red and blue pigments. Purples are varied: thread-like, cylindrical, coral-like, etc. They can be found even at a depth of 100–200 meters(slide 21).

In which seas do phyllophora, porphyry, etc. live?

Why are they different?

Problematic question(slide 22)

Do algae live at the same level?(slide 23)

5. Conversation with students to check acquired knowledge

What is the significance of algae for humans?

1. Fish and other animals eat.
2. Chemical industry - iodine, potassium salts, cellulose, alcohol, etc.
3. Fertilizer and livestock feed.
4. Agar-agar, used in bakery, confectionery, paper and textile industries. Microorganisms are grown.
5. For a variety of dishes,(slide 24)

Conclusion: The presence of algae is a necessary condition for the normal life of a reservoir.

Biology lesson 6th grade

Lesson plan on the topic: “Algae. General characteristics".

The purpose of the lesson: form an idea of ​​​​algae, a concept of structure, teach to distinguish algae from other plants

Planned result : get acquainted with the diversity of algae, identify the distinctive features of algae, learn to treat nature with care.

Tasks:

Educational – developing students’ understanding of lower plants using the example of algae.

Educational – the formation of communicative universal educational actions, including the ability to listen and enter into dialogue, to participate in a collective discussion of problems.

Developmental – development of research skills of schoolchildren.

Lesson steps

Teacher

Students

1.Organizational

Greets students. Checking absentees. Sets up for work.

Greetings from the teachers. Get ready for active work.

2. Updating knowledge

Students are divided into two options, cards with tasks are distributed, and points are awarded for each task.

Complete tasks

(6 min)

3.Learning new material

We told you that plants are divided into two large groups - higher and lower plants. What plants are classified as lower? Why?

Today we will take a closer look at algae.

What exactly should we know about them?

What do you already know about algae?

Teacher's story Listen and watch presentation slides

A ) Habitats

Algae are the most ancient animals on Earth. The bulk of algae lives in the aquatic environment, but algae are also found in the soil, air, on tree trunks, and can also form symbiosis with fungi, forming lichens.

In the aquatic environment, they can be part of plankton (phytoplankton) or grow on the bottom of reservoirs.

So, let’s summarize the “Habitat” item:

B) The structure of an algae cell.

Among algae there are unicellular and multicellular plants.

Algae evolved from different ancestors. Botanists count 30 thousand species of algae - from single-celled organisms to giants tens of meters long. General characteristics of algae: the body is thallus or thallus, not divided into organs. In structure, thaw can be unicellular (diatoms, some green algae), multicellular (green, red, brown algae).

Living environment - water, wet areas on land.

Coloring is provided by pigments (dyes). Often, divisions of algae are named based on the body coloration provided by pigments. Algal chloroplasts are called chromatophores. Although all algae contain chlorophyll, not all are green. The visible color of chromatophores is different. In taxonomy, it is customary to distinguish the departments of green, brown, red, and diatoms. Algae cells are similar in structure to the cells of land plants.

The top is covered with a cell membrane rich in cellulose and pectin.

The center of the cell is the nucleus.

Algae contain chlorophyll, contained in chromatophores of various structures - pear-shaped, spiral-shaped (spirogyra), etc.

There are also vacuoles and cytoplasm, a red light-sensitive eye.

The structure of the thallus. (Slide6)

The body of algae is represented by a thallus and has no real tissues, and therefore no organs - leaves, stems, roots. The body of some algae resembles that of land plants, with leaves and a stem, but in fact they are branches of a thallus.

(Slide) In algae living at the bottom of reservoirs, the body is attached to the substrate by rhizoids or a lamellar disk.

(Slide) Let's summarize the point "Structure of algae"

IN) Reproduction

They reproduce by vegetative, asexual and sexual means. During vegetative propagation of unicellular algae, the cell is divided into two parts. The thalli of multicellular algae are divided into several parts.

During asexual reproduction, spores are formed with or without flagella. Adult algae grow from the spores.

During sexual reproduction, mature male and female reproductive cells unite and form a zygote. It splits into pieces and new algae are formed.

Let’s summarize the point “Reproduction"

So, guys, today we took a closer look at algae. Let's summarize the lesson. What new have you learned about algae?

Answers:

Seaweed.

Because do not have separate organs.

Habitats, internal structure. Diversity. Reproduction.

They conclude:

Algae can live

in water, in soil,

on tree trunks and

form a symbiosis

with mushrooms

They conclude:

Algae may be

unicellular and

multicellular.

The cell consists of: nucleus, chromatophore, cytoplasm, membrane. Some representatives may have flagella and an ocellus.

Draw conclusions about three types of algae reproduction.

Answer teacher questions

4. Consolidation of the studied material

Frontal survey. For each correct answer, the student is awarded 1 point.

Where do algae live?

How do algae reproduce?

How many species do botanists count?

What is thallus?

How does the body of algae attach to the substrate?

What divisions of algae are distinguished in taxonomy?

Depending on what, the algae were divided into sections?

Calculate your points and announce them.

12-15 points “5”

11- 7 points “4”

6- 4 points “3”

Homework

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