Algae - a vast and heterogeneous group
lower plants.
Algae are the most numerous and one of the
the most important photosynthetic organisms on the planet.
They are found everywhere: in the seas and oceans, in fresh water, on wet soil and on the bark.
trees.
Diversity of algae
Algae include unicellular, multicellular and colonial organisms. The cells of some algae contain many nuclei, others do not contain intercellular partitions. Cell walls are usually composed of cellulose. Cells (similar to plants) can be connected end-to-end, forming chains or threads, sometimes branched. The conducting system and roots are absent; motionless forms are attached to the bottom by branched outgrowths - rhizoids.
Algae sizes
algae vary from microscopic (micrometers) to gigantic (tens of meters).
The structure of unicellular algae
The structure of multicellular algae
Algae movement
Many solitary and colonial algae
capable of movement. Some of the algae
1 or 2 flagella are used for locomotion. Others crawl like amoeba, now squeezing, then
stretching parts of your body. Movement of thirds
due to water currents created by the cytoplasm.
Algae nutrition
Algae are autotrophs and contain the green pigment chlorophyll.
The pigment is located in the algae cell in a special ribbon-shaped or star-shaped organelle called
chromatophore.
Algae color
However, algae are not only green: among them you can find specimens of brown, red, yellow and many other tones.
Algae reproduction
Algae do not form flowers and seeds; most of them reproduce by spores.
Spores and gametes are formed either in ordinary cells or in special organs - gametangia (male - in antheridia, female in oogonia or archegonia); in some of them, spores and gametes have flagella.
The sexual processes are very diverse: these are isogamy (male and female gametes are the same), anisogamy (both gametes are mobile, but differ in size) or oogamy (the female gamete is motionless and much larger than the male gamete).
Sexual and asexual |
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algae breeding |
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The zygote develops immediately or after a certain period |
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In primitive algae, both spores and gametes give one and |
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the same individual; in more highly developed functions of the sexual and |
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asexual reproduction is performed by different individuals - |
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sporophytes and gametophytes. |
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The latter can germinate simultaneously and in the same |
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conditions, in different places or in different seasons. |
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In higher algae, alternation of generations occurs; |
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in this case, either the gametophyte germinates on the sporophyte, or |
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vice versa. |
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In addition, asexual reproduction is widespread - |
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division in two (unicellular algae), or |
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vegetatively - parts of the thallus or kidneys. |
Lesson objectives:
- To acquaint students with the characteristics of the habitat, structure and activity of algae, as the most simply organized representatives of the plant world;
- Explain how algae reproduce;
- Show the importance of algae in nature and human life.
Lesson type:
Lesson of studying and primary consolidation of new knowledge.
Equipment:
Algae table, presentation of the topic (multimedia support) “Algae”, individual cards, algae drawings, algae salad recipe.
During the classes
1. Organizational moment:
Greeting students - 1 minute, (slide 1, 2)Attachment 1
Preparation for the survey - 3 minutes.
2. Checking homework:
- Work on individual cards (4 people)
- plant sizes - Fig. 30 ( Annex 3, Appendix 4)
- variety of plants - rice 31, 32, 33 ( Annex 2)
– work with the mini-football class (slide 3, 4, 5) - front poll. Warm-up “Terms” (1-4 people)
Botany is...
- lower plants are ... ..
The higher plants are...
- thallus, or thallus is ... - Individual work with a student (slide 6). Blackboard work. 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 a botanist study?
- Why were plants singled out as an independent kingdom?
What is the importance of plants in nature?
What is the importance of plants in human life?
Why should plants be protected?
Evaluation of student responses
4. Learning new material (25 min)
9 Recording the topic of the lesson in the notebook). Teacher's story (slide 7).
Algae are the most ancient animals on Earth. They mostly live in the water, but there are species that live in damp areas of soil, tree bark and other places with high humidity.
Algae include unicellular and multicellular plants. Algae are among the lower plants. They have no roots, no stems, no leaves. Algae reproduce by simple cell division or spores.
Algae are descended 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, shady places. You, obviously, observed the “blooming” of water in puddles and ponds in summer, and in strong light in an aquarium (slide 9). "Blossoming" water has an emerald shade. Under a microscope, a drop of water shows many single-celled green algae, which give it an emerald hue. (slide 10).
In the "bloom" of water, the most common unicellular algae
Chlorella.* Structure: shell, cytoplasm with a nucleus, and in the cytoplasm a green chromatophore (slide 11).
* Reproduction of chlorella (slide 12).
* Green unicellular algae, common in fresh water and on wet soils, (slide 13)
Chlamydomonas(from the Greek “the simplest organism, covered with clothes-shell” (slide 14). It has a pear-shaped shape, moves in the water with the help of 2 flagella.
* The structure (p. 35 chlamydomonas and chlorella) is covered on the outside with a transparent membrane, under which there is a cytoplasm with a nucleus, a red “eye” (light-sensitive red 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)
In the workbook, complete laboratory work No. 39, p. 18.
Dynamic pause (movement of algae during flow)
2) Multicellular algae
Green algae live in flowing water bodies attached to reefs and snags (ulotrix). In stagnant and slowly flowing waters, bright green pebbles 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). Chara algae, which have a complex structure, live in freshwater water. (slide 18, 19).
In multicellular representatives of green algae, the body (thallus) has the form of filaments or flat leaf-shaped formations. Chara algae have rhizoids (from the Greek “rhiza” - root and “Eidos” - view), colorless branched filamentous cells. They are anchored to the ground.
Brown algae. Marine plants, external sign of yellowish-brown color of thalli. What is a thallus? Filamentous, spherical, lamellar, bushy. 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 fresh water. Very few are unicellular. Sizes from a few centimeters to 1 meter in length. In addition to chlorophyll, red and blue pigments are contained. Crimson flowers are diverse: filamentous, cylindrical, coral-like, etc. They can be found even at a depth of 100–200 meters. (slide 21).
In what seas do phyllophora, porphyra, etc. live?
Why are they different?
? problematic issue (slide 22)
Do algae live on the same level? (slide 23)
5. Conversation with students to test the acquired knowledge
What is the importance of algae for humans?
- They feed on fish and other animals.
- Chemical industry - iodine, potassium salts, cellulose, alcohol, etc.
- Fertilizer and feed for livestock.
- Agar-agar, use in bakery, confectionery, paper and textile industries. Grow microorganisms.
- For a variety of dishes (slide 24)
Conclusion: The presence of algae is a necessary condition for the normal life of a reservoir.
(Recipes for seaweed salads), (slide 25)
6. Fixing the material
- Show pictures of different types of algae. It is necessary to name the species or genus, class ... ( Annex 7)
- Individual work at the blackboard. Qualification of the algae department, (deepening), ( Annex 5, Appendix 6)
7. Assessing the work of students in the lesson.
- For work in the lesson, give all the children a recipe for making algae salad “Vitamin” ( Annex 8).
8. Explanation of homework.
To the house § 12, ex. 40, 41, 42 in the workbook.
9. Reflection a pond is offered, on which you need to attach algae of different colors according to your mood and interest in the lesson. (According to Luscher).
slide 1
Seaweed
slide 2
Algae are lower plants
Algae are an extensive and heterogeneous group of lower plants. Algae are the most numerous and one of the most important photosynthetic organisms for the planet. They are found everywhere: in the seas and oceans, in fresh water, on wet soil and on the bark of trees.
slide 3
Diversity of algae
Algae include unicellular, multicellular and colonial organisms. The cells of some algae contain many nuclei, others do not contain intercellular partitions. Cell walls are usually composed of cellulose. Cells (similar to plants) can be connected end-to-end, forming chains or threads, sometimes branched. The conducting system and roots are absent; fixed forms are attached to the bottom by branched outgrowths - rhizoids.
slide 4
Algae sizes
Algae sizes vary from microscopic (micrometers) to gigantic (tens of meters).
slide 5
The structure of unicellular algae
slide 6
The structure of multicellular algae
Slide 7
Algae movement
Many solitary and colonial algae are capable of movement. Some of the algae use 1 or 2 flagella for locomotion. Others crawl like amoeba, now squeezing, now stretching parts of their bodies. The movement of the third is due to the currents of water created by the cytoplasm.
Slide 8
Algae nutrition
Algae are autotrophs and contain the green pigment chlorophyll. The pigment is located in the algae cell in a special ribbon-shaped or star-shaped organelle called the chromatophore.
Slide 9
Algae color
However, algae are not only green: among them you can find specimens of brown, red, yellow and many other tones.
Slide 10
Algae breeding
Algae do not form flowers and seeds; most of them reproduce by spores. Spores and gametes are formed either in ordinary cells or in special organs - gametangia (male - in antheridia, female - in oogonia or archegonia); in some of them, spores and gametes have flagella. The sexual processes are very diverse: these are isogamy (male and female gametes are the same), anisogamy (both gametes are mobile, but differ in size) or oogamy (the female gamete is motionless and much larger than the male gamete).
slide 11
Sexual and asexual reproduction of algae
The zygote develops immediately or after a period of rest. In primitive algae, both spores and gametes are produced by the same individual; in more highly developed, the functions of sexual and asexual reproduction are performed by different individuals - sporophytes and gametophytes. The latter can germinate simultaneously and under the same conditions, in different places or in different seasons. In higher algae, alternation of generations occurs; in this case, either the gametophyte germinates on the sporophyte, or vice versa. In addition, asexual reproduction is widespread - by dividing in two (unicellular algae), or vegetatively - by parts of the thallus or by kidneys.
slide 12
Algae habitats
Algae are predominantly aquatic creatures that live in both marine and fresh water. Small free-floating algae are part of the plankton; others are attached to the bottom, sometimes forming entire thickets. Most of them live at depths up to 40 m; with good water transparency, they can also be found at a depth of up to 200 m. In stagnant reservoirs, well warmed by the sun, water blooms are observed. Algae live in the soil, on trees and rocks. Some green algae symbiote with fungi to form lichens.
slide 13
Application of algae
Algae is the main source of organic matter on Earth (more than 80% of the total biomass created per year); almost all aquatic ecological chains begin with them. They release into the atmosphere more than half of the total amount of oxygen released by plants per year. Algae is the main food for many marine animals; some are eaten by humans. In coastal areas, algae are used for fertilizer and livestock feed.
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Slides captions:
Seaweed
introduce students to a group of plants called algae; - to acquaint with the habitat of algae; - to reveal the structural features of the body of unicellular and multicellular algae; - to give an idea about the methods of reproduction of algae; - continue to form students' knowledge of higher and lower plants.
Updating knowledge What sub-kingdoms is the plant kingdom divided into? By what signs? Where do plants live? What is the importance of plants in nature? How do humans use plants?
green algae
Brown algae 1 - macrocystis pear-shaped; 2 - neocystis Lutke; 3 - antarctic durvillea; 4 - thalassiophyllum trellised; 5 - perforated agarum
red algae
Algae Habitat Algae live in both fresh and salt water bodies, can live in stagnant and running water, and they also live on moist soil, tree bark, in an aquarium, on the surface of the soil in a pot of indoor flowers.
Chlamydomonas
Stops. Loses flagella (1). Its content is divided into 4 parts (2). Each part forms flagella and its own shell (2). 4 cells-spores or zoospores were formed, which perform the function of settling. The shell of the mother cell is torn, and small chlamydomonas swim out into the water (3). After swimming in the water for some time, the cells grow to the size of the mother (4) and again begin asexual reproduction (1-4). Under favorable conditions
In the mother cell, biflagellated gametes are formed (1, 2). They come out of the shell of the mother cell (3). Merge in pairs with other individuals (4, 5). A zygote is formed, covered with a dense shell and hibernates (6). In the spring, favorable conditions allow the zygote to divide. As a result, 4 chlamydomonas are formed (7). Young chlamydomonas feed, grow to maternal size (1, 8). Under adverse conditions (in autumn) http://biouroki.ru/content/page/711/polovoe.png
Spirogyra Filamentous algae up to 8-10 cm. Accumulations of filaments of spirogyra form mud. Filaments unbranched, formed by one row of cylindrical cells.
The role of algae in nature In the process of photosynthesis, they release oxygen, which they need for breathing. Food for many marine animals. Shelter for fish and many other animals. Enrichment of water with oxygen during photosynthesis. Some species are involved in soil formation when they fall on barren substrates. Some species are part of complex organisms (lichens).
The role of algae in human life and activities They are food for humans. Used as an additive to livestock feed. Manufacture of fertilizers. Use in the chemical industry (iodine, alcohol, acetic acid). Biological wastewater treatment. Obtaining medicines and biologically active food supplements.
Harm caused by algae: Excessive growth in irrigation canals makes it difficult to supply water. Excessive breeding in fish ponds makes it difficult to catch fish seasonally. Excessive breeding of algae in navigable places leads to difficulty in navigation.
On the topic: methodological developments, presentations and notes
The purpose of the lesson: Recall and consolidate with students the reproduction of algae, their structure; to consolidate the concept of photosynthesis, the cosmic role of green plants on the planet; repeat the basic biological...
The structure and activity of green algae.
the study of the topic is not forced, the guys perform creative tasks and solve the tasks assigned to them ...
Biology lesson "Algae", Grade 6
A lesson in learning new material. Lesson Objectives: To introduce students to a group of plants called algae; - to get acquainted with the habitat of algae; - to reveal the structural features of the body of a single cell ...
slide 1
Seaweed
slide 2
Algae are lower plants
Algae are an extensive and heterogeneous group of lower plants. Algae are the most numerous and one of the most important photosynthetic organisms for the planet. They are found everywhere: in the seas and oceans, in fresh water, on wet soil and on the bark of trees.
slide 3
Diversity of algae
Algae include unicellular, multicellular and colonial organisms. The cells of some algae contain many nuclei, others do not contain intercellular partitions. Cell walls are usually composed of cellulose. Cells (similar to plants) can be connected end-to-end, forming chains or threads, sometimes branched. The conducting system and roots are absent; fixed forms are attached to the bottom by branched outgrowths - rhizoids.
slide 4
Algae sizes
Algae sizes vary from microscopic (micrometers) to gigantic (tens of meters).
slide 5
The structure of unicellular algae
slide 6
The structure of multicellular algae
Slide 7
Algae movement
Many solitary and colonial algae are capable of movement. Some of the algae use 1 or 2 flagella for locomotion. Others crawl like amoeba, now squeezing, now stretching parts of their bodies. The movement of the third is due to the currents of water created by the cytoplasm.
Slide 8
Algae nutrition
Algae are autotrophs and contain the green pigment chlorophyll. The pigment is located in the algae cell in a special ribbon-shaped or star-shaped organelle called the chromatophore.
Slide 9
Algae color
However, algae are not only green: among them you can find specimens of brown, red, yellow and many other tones.
Slide 10
Algae reproduction
Algae do not form flowers and seeds; most of them reproduce by spores. Spores and gametes are formed either in ordinary cells or in special organs - gametangia (male - in antheridia, female - in oogonia or archegonia); in some of them, spores and gametes have flagella. The sexual processes are very diverse: these are isogamy (male and female gametes are the same), anisogamy (both gametes are mobile, but differ in size) or oogamy (the female gamete is motionless and much larger than the male gamete).
slide 11
Sexual and asexual reproduction of algae
The zygote develops immediately or after a period of rest. In primitive algae, both spores and gametes are produced by the same individual; in more highly developed, the functions of sexual and asexual reproduction are performed by different individuals - sporophytes and gametophytes. The latter can germinate simultaneously and under the same conditions, in different places or in different seasons. In higher algae, alternation of generations occurs; in this case, either the gametophyte germinates on the sporophyte, or vice versa. In addition, asexual reproduction is widespread - by dividing in two (unicellular algae), or vegetatively - by parts of the thallus or by kidneys.
slide 12
Algae habitats
Algae are predominantly aquatic creatures that live in both marine and fresh water. Small free-floating algae are part of the plankton; others are attached to the bottom, sometimes forming entire thickets. Most of them live at depths up to 40 m; with good water transparency, they can also be found at a depth of up to 200 m. In stagnant reservoirs, well warmed by the sun, water blooms are observed. Algae live in the soil, on trees and rocks. Some green algae symbiote with fungi to form lichens.
slide 13
Application of algae
Algae is the main source of organic matter on Earth (more than 80% of the total biomass created per year); almost all aquatic ecological chains begin with them. They release into the atmosphere more than half of the total amount of oxygen released by plants per year. Algae is the main food for many marine animals; some are eaten by humans. In coastal areas, algae are used for fertilizer and livestock feed.