Current page: 1 (total for book is 11 pages) [accessible passage for reading: 8 pages]

V.V. Pasechnik
Biology. Variety of angiosperms. 6th grade

How to work with the textbook

Dear friends!

This year you will continue to get acquainted with biology - the science that studies wildlife. You have in your hands a textbook that will become your guide in the diverse and wonderful world of living organisms. You will learn about the features of the structure, life processes, diversity and classification of angiosperms, as well as their role in nature and human life.

The text of the textbook is divided into chapters and paragraphs. The necessary section can be found on the table of contents. Read the chapter title, introductory text, and information about what you learn and learn. This will help you understand which material you need to pay special attention to.

At the beginning of each paragraph are questions to help you remember what you studied earlier. This will allow a better understanding and assimilation of the new material.

The terms and names of plants to be memorized are typed. in italics.

Carefully review and study the illustrations, read the captions to them - this will help you better understand the content of the text.

At the end of each paragraph on a blue background are the basic concepts that you need not only to remember, but also to be able to explain.

You can check how well you have learned the material you read by answering the questions at the end of the paragraph. After them are given the task, mandatory for all. This applies to the "Think" heading, which will help you learn to analyze the material studied, and the "Tasks" heading.

A prerequisite for the successful mastery of biological knowledge is the performance of laboratory work. Laboratory work is usually performed in class, using instructions, tasks and questions for them.

Also in the textbook contains descriptions of seasonal observations in nature.

Useful tips

1. Preparing for homework, think about what you may need, in addition to the textbook.

2. While reading the text, relate it to the illustrations that are in the paragraph. Pay attention to key concepts and information highlighted in the text.

3. Think about how the material under study can be useful and be used in your life.

4. Make your own paragraph summary in a notebook or on a computer in the form of text or a diagram. Synopsis should contain basic thoughts, terms and conclusions.

5. When completing homework and preparing a message, use additional literature and Internet resources.

6. Remember that the success of the work depends entirely on your desire, perseverance, determination and perseverance.

We wish you success!

Chapter 1. Structure and diversity of angiosperms

Angiosperms, or Flowering, are a group of the most highly organized plants. Their organs are divided into vegetative and reproductive.

Vegetative   (from the Latin word "vegetative" - ​​plant) organs make up the body of the plant and carry out its main functions, including vegetative reproduction. These include the root and the shoot.

Reproductive or generative   (from the Latin word “general” - to produce), organs are associated with sexual reproduction of plants. These include a flower and a fruit with seeds.

From this chapter you will learn

On the external and internal structure of the organs of a flowering plant, on their modifications;

On the dependence of the structural features of the flowering plant on the habitat;

On the role of flowering plants in nature and human life.

You will learn

Recognize the organs of a flowering plant;

To establish the relationship of the features of the structure of the organ with the habitat.

§ 1. The structure of the seed

1. What plants have seeds?

2. What is the role of seeds in plant life?

3. What are the advantages of seeds over disputes?

The life of a flowering plant begins with a seed. Plant seeds vary in shape, color, size, weight, but they all have a similar structure.

The seed consists of peel, germ   and contains a supply of nutrients. The germ is the germ of a future plant. The seed supply of nutrients is in special storage tissue - endosperm (from the Greek words "endos" - inside and "sperm" - a seed). In the bud distinguish germinal root, stalk, bud   and cotyledons.   Cotyledons are the first leaves of a plant germ. Plants that have one seed-seed in the seed bud are called monocots.   Monocotyledonous include wheat, corn, onions and other plants.

Beans, peas, apples and many other seed germs have two cotyledons. These plants are called dicotyledonous

The seeds of many plants, such as wheat, onions, and ash, have a small germ. Almost the entire volume of their seed is stored in the endosperm. In others, like an apple tree, almonds, on the contrary, the germ grows to the time of seed ripening so that it displaces and absorbs the endosperm, which leaves only a small layer of cells under the seed coat. In pumpkin, beans, arrowhead, and parts, the mature seed consists only of the germ and seed coat. In such seeds, the supply of nutrients is in the cells of the embryo, mainly in the cotyledons.

  (Fig. 1). Perform lab work by examining large bean seeds.

Fig. 1. The structure of the seeds of dicotyledonous plants

The structure of the seeds of dicotyledonous plants

1. Consider dry and swollen bean seeds. Compare their size and shape.

2. On the concave side of the seed, find the hem - the place of attachment of the seed to spike blade.

3. Above the hem is a small hole - micropyle   (from the Greek words "micros" - small and "saw" - the gate). It is clearly visible in the swollen semen. Air and water penetrate through the micropyle into the seed.

4. Remove the shiny dense skin. Examine the fetus. Find cotyledons, germinal root, stalk, bud.

5. Draw the seed and sign the names of its parts.

6. Find out in which part of the bean seed the nutrients are located.

7. Using the textbook, find out in which parts of the seed the other dicotyledons store nutrients.

The structure of the seeds of monocotyledonous plants   (Fig. 2). Seeds of monocotyledonous plants have a different structure. Consider it on the example of the seeds of cereals (wheat, rye, corn).

Fig. 2. The structure of the seeds of monocotyledonous plants

Wheat seed is dressed in golden yellow leathery pericarp.   It has grown together with the seed coat so tightly that it is impossible to separate them. Therefore, it is more correct to say not the seed of wheat, but the fruit called caryopsis.

Wheat grain structure

1. Consider the shape and color of the wheat weevil.

2. Using a dissection needle, try to remove a part of the pericarp from swollen and dry kernels. Explain why it is not removed.

3. Consider a magnifying glass cut along the grain. Find the endosperm and germ. Using the picture of the textbook, study the structure of the embryo.

4. Draw a grain of wheat and sign the names of its parts.

5. Using the textbook, find out what features of the structure can have the seeds of other monocotyledonous plants.

Seeds of other monocotyledonous plants, for example, onions, lilies of the valley, also have an endosperm, but it surrounds the embryo, and does not adhere to it on the one hand, as in wheat and other cereals.

Chastuhi ripened seeds do not have endosperm. The horseshoe-shaped seed consists of a thin peel and an embryo, in the cotyledon of which all the reserves accumulated during the ripening of the seed are concentrated.

So the seeds have a seed coat and a germ. In dicotyledonous plants, the embryo contains two cotyledons, and the storage nutrients are usually located either in the embryo itself or in the endosperm. The monocots embryo has only one cotyledon, and the nutrients are usually in the endosperm.

SINGLE-AND-DOUBLE PLANTS. COTYLEDON. ENDOSPERM. BEGIN TESTA. FUNICLE. MICROPILE

Questions

1. What plants are called dicots, and which - monocots?

2. What is the structure of the bean seed?

3. Is there a supply of nutrients in the seeds of beans, ash, almond?

4. What is the structure of wheat grain?

5. How is the endosperm located in different monocotyledonous plants?

6. How do embryos of dicotyledons and monocotyledons differ?

Think

Why are seed plants most common in nature?

Tasks

Review the apple and pumpkin seeds and find out how they work. Sketch the structure of the seed, draw conclusions. Discuss the results with other students in the next lesson.

Memo

Studying the structure of plant organs or any phenomenon of nature, you, without knowing it, use the method of analysis, which is an important component of thinking. To make the results of your work more effective, get acquainted with the rules of the analysis.

Analysis is the dismemberment, the division of the whole into its component parts, the selection of individual aspects and properties of the object.

Instructing-memo sequence of actions during the analysis:

1. Carefully study the object as a whole.

2. Divide the object into its component parts.

3. Learn the features of each part.

4. Establish subordination (interconnection) of parts.

5. Try to highlight the function parts.

Do you know that…

85% of species of flowering plants have seeds with endosperm (large or small), and only 15% of species do not have it.

The largest are the seeds of the Seychelles palm. They reach a length of almost 50 cm and have a mass of more than 10 kg.

§ 2. Types of roots and types of root systems

1. What is the role of the roots in plant life?

2. How are roots different from rhizoids?

3. Do all plants have roots?

Root functions.   The roots fix the plant in the soil and firmly hold it throughout life. Through them, the plant receives water from the soil and minerals dissolved in it. In the roots of some plants, reserve substances can be deposited and accumulated.

Types of roots.   There are three types of roots: main subordinate   and lateral   (Fig. 3). When seed germinates, the germinal root first develops. It turns into the main root. The roots that form on the stems, and in some plants and on the leaves, are called adventitious. From the main and adventitious roots are lateral roots.

Fig. 3. Types of roots

Fig. 4. Types of root systems

Types of root systems.   All the roots of one plant form the root system. There are two types of root systems - rod and fibrous systems (Fig. 4). The root system, in which the core root similar to the core is developed, is called pivotal.   The majority of dicotyledonous plants, for example sorrel, carrots, beets, etc., have a rod root system (Fig. 5).

Usually, the root root system is buried only in young plants grown from dicotyledon seeds. In perennial plants (buttercup, strawberry, plantain) often the main root dies off, and adventitious roots grow from the stem.

Fig. 5. Rod root systems of various dicotyledonous plants

Mossy   called the root system of adventitious and lateral roots. The main root in plants with a fibrous system is underdeveloped or dies early. The loquate root system is characteristic of monocotyledonous plants - wheat, barley, onion, garlic, etc.

In order to learn to distinguish the types of root systems, do a lab.

Rod and fibrous root systems

1. Consider the root systems of the plants proposed to you. How do they differ?

2. Read in the textbook which root systems are called core, which are fibrous.

3. Select plants with taproot.

4. Select plants with a fibrous root system.

5. According to the structure of the root system, determine which plants are monocotyledonous, which are dicotyledonous.

6. Fill in the table "Structure of root systems in different plants."

Fig. 6. Hilling of tomatoes

MAIN, SIDE, ADDITIONAL ROOTS. BOTTOM AND URINARY ROOT SYSTEMS

Questions

1. What are the functions of the root?

2. Which root is called the main, and which - subordinate and side?

3. Which root system is called the core, and which - fibrous?

Think

Hilling is widely used in the cultivation of corn, potatoes, cabbage, tomatoes and other plants, i.e. the lower part of the stem is sprinkled with earth (Fig. 6). Why do this?

Tasks

1. In houseplants Coleus and Pelargonium, adventitious roots are easily formed. Carefully cut several side shoots with 4–5 leaves. Remove the two bottom leaves and place the shoots in glasses or jars of water. Observe the formation of adventitious roots. After the length of the roots reaches 1 cm, plant the plants in pots with nutrient soil. Water them regularly.

2. Record the results of the observations and discuss them with other students.

3. Sprout the seeds of radish, peas or beans and wheat grains. You will need them in the next lesson.

Do you know that…

In wheat, the mass of the roots is more than 100 times the mass of the aerial parts of the plant. Apple roots penetrate the soil to a depth of 3-4 m, and diverge by 15 m to the sides of the trunk.

§ 3. Zones of the root

1. What is fabric?

2. What types of plant tissue do you know?

Root cap. Zones of division and stretching.   Look at the light roots of the seedlings (beans, wheat, or radish). You will see that their tips are slightly darker and denser than the rest of the root. This is because the tip of the root is covered like a thimble, root cap   (Fig. 7).

Root cap formed by cells cover cloth.   Root cap cells protect the root tip from damage by hard particles of the soil. These cells are short-lived, they gradually die off and are exfoliated, and instead of the dead, new ones are constantly being formed.

Root cap protects the area formed by small, tightly adjacent to one another living cells. it educational fabric.   The cells here are constantly dividing, their number is increasing, so this section is called division zone.

Fig. 7. Structure and zones of the young root

Above located stretch zone   (growth zone). Here the cells are drawn out, as a result of which the root grows in length (Fig. 8).

Root hairs. Suction zone   Above the root tip, the superficial cells form a multitude of thin and transparent root hairs   (Fig. 9). In some plants, root hairs can be seen without a microscope. In many plants, they resemble a light down covering part of the root.

The root hair is a relatively long outgrowth of the external cell of the root. Under the cell membrane in it are the cytoplasm, nucleus, colorless plastids and the vacuole with cell sap.

Fig. 8. Apical root growth

Fig. 9. Root hairs sprout

The length of the root hairs is usually not more than 10 mm. They are short-lived and most of the plants live only a few days, and then die. New hairs arise from younger surface cells located closer to the root tip.

Thus, in the older part of the root zone, the root hairs constantly die off, and in the younger part they form again. Therefore, the suction zone, like other zones, is constantly moving and is always near the tip of the root.

Penetrating between soil particles, root hairs tightly adhere to them and suck water from the soil with mineral substances dissolved in it.

Root hairs significantly increase the suction surface of the root. Therefore, the plot of the root, on which the root hairs are located, is called suction zone.

Root cap and root hairs

1. Consider the radish root or wheat germ with the naked eye, and then with a magnifying glass. Find the root cap at the end of the spine.

2. Pay attention to the part of the root above the root cap. Find outgrowths in the form of a gun - root hairs. Read in the textbook what they have structure and value.

3. Place the spine on a glass slide in a drop of water tinted with ink and examine under a microscope. Match what you see under a microscope with a drawing of a textbook, draw and make inscriptions.

4. What is common in the structure of the root hair and onion skin cells? What explains the difference in their form?

5. Make a conclusion.

When transplanting plants, young root areas that carry root hairs can be easily damaged. Therefore, the seedlings of vegetable and ornamental plants are recommended to grow in special peat pots. In this case, the roots during transplantation are not damaged and the seedlings quickly take root.

Conduction area   Above the suction zone, i.e., further away from the root tip, is holding area. Through the cells of this root section, water with dissolved minerals moves to the stem. There are no root hairs here, surface tissue is on the surface. On this site the root branches. The composition of the conductive tissues of the root zone includes vessels. According to him, water and substances dissolved in it from the root enter the stem and leaves. In conducting tissues there are also cells through which organic substances formed in the leaves and stalks enter the root.

The strength and elasticity of the root provides mechanical fabric.   It consists of elongated cells with thick shells along the root. They lose their contents early and are filled with air. Most of the root are the cells of the main tissue.

ROOT COVER ROOT HAIR. ROOT ZONES: FISSIONS, EXTENSIONS, SUCTIONS, HOLDING

Questions

1. What sites (zones) can be distinguished, considering a young root?

2. What is the meaning of the root cap?

3. Where is the cell division? How do her cells differ from cells in other zones?

4. Where is the root stretch zone? What is its meaning?

5. What is the root hair? What structure does it have?

6. Why is one of the root zones called the suction zone?

7. Where is the root area located? Why is it so called?

8. What is fabric?

9. What tissues are distinguished in plant roots?

Fig. 10. Development of the plant root system

Think

Knowing the structure of the root, can a person influence the formation of the root system? If so, how?

Tasks

1. A pick is the pinching off of the root tip when young plants are seated with the help of a pointed spike. What impact does it have on the development of the root system of plants (Fig. 10)?

Tasks for the curious

1. Carefully remove the wheat germ from the soil and examine it. Which root zone is covered by adhering soil? Explain why.

2. Pinch off the tips of the root of young plants of cabbage, aster, beans, etc. Watch the development of root systems of control and experimental plants. Discuss the results of the experiment with other students.

Do you know that…

There are about 700 root hairs per 1 mm 2 of the corn root absorption zone.

One plant rye root system consists of 14 million small roots. If we pull all these roots into one line, they will occupy 600 km (the approximate distance from Moscow to St. Petersburg). On these roots, 15 billion root hairs were counted. Their total length is 10 thousand km (the distance from Riga to Vladivostok). If you want to make sure of this, then grow a rye plant in a large wooden box. By the time of earing, open the walls of the box and carefully wash the roots off the ground. Now count. Are you convinced?

§ 4. Conditions of growth and modification of roots

1. What types of roots do you know?

2. What are the functions of the root?

The depth of penetration of the plant roots into the soil depends on the conditions in which they grow (Fig. 11). Thus, on dry fields, the roots of wheat reach 2.5 m in length, and on irrigated fields only 50 cm, but there they are thicker.

Because of the permafrost in the tundra, the roots of plants are located near the surface, and the plants themselves are stunted. For example, in a dwarf birch, roots penetrate the soil to a depth of no more than 20 cm. Desert plants have very long roots, since the groundwater is deep. At leafless leafless roots go into the soil at 15 m (Fig. 12).

In the process of adapting to the conditions of existence, the roots of some plant species have changed and began to perform additional functions.

Radishes, turnips, beets, turnips, rutabaga and other plants store nutrients in root vegetables   (Fig. 13). Both the main root and the lower parts of the stem participate in the formation of root crops.

Root tubers   appear as a result of thickening of the lateral or adventitious roots of plants such as dahlia, chistyak (Fig. 14).

Ivy develops accessory roots-trailers.   They attach the plant to a support, for example, to a vertical wall or tree trunk, and due to this it grows upwards, bringing the leaves to light.

Fig. 11. Depth of penetration into the soil of plant roots

In plants that live like orchids, on trunks and branches of tropical rainforest trees aerial roots   hanging down freely (see fig. 14). Such roots absorb rainwater and help the plants to live in these unique conditions.

Respiratory roots   willow is brittle and some other plants that settle on the muddy banks of rivers (Fig. 15). These roots grow vertically up until they reach the surface of the soil. Along the intercellular spaces, the air moves to the roots that are deeper under conditions of lack of oxygen.

In some tropical trees, for example, in banyan trees, adventitious roots grow on the trunks and large branches, growing to the ground and serving props   (Fig. 16).

Fig. 12. The root system and the appearance of leafless leaf shrub

Fig. 13. Root carrots and turnips

Fig. 14. Root tubers of dahlias and aerial orchid roots

Fig. 15. Respiratory roots marsh cypress

Fig. 16. Banyan Ridges

Roots of aquatic plants rooting in the soil lack root hairs.

ROOTS. ROOT CLUBS. AIR ROOTS. RESPIRATORY ROOTS

Questions

1. What is the impact of environmental conditions on the root system of plants?

2. What are the related root modifications?

3. What are the roots of carrots, dahlias, ivy, orchids?

4. Which of the plants you know form roots?

5. What is the role of roots in the life of biennial plants?

Think

1. What is the reason for the modification of the roots of plants?

2. Why are there no root hairs on the roots of aquatic plants?

Phenological observations

In the spring, sow carrots, beets or turnips in the garden. A week after the emergence of shoots, and then once a week, carefully remove them one by one from the soil and draw. Make an album of these drawings and follow the development of root crops. In the fall, prepare a report on the results of your observations and discuss them with students in the classroom.

Do you know that…

From sugar beet roots get sugar.

In maize, the root system grows to the side of the stem by almost 2 m, and for onions by 60–70 cm. The majority of the roots of most plants grow at a depth of 15–18 cm from the soil surface. Carrot roots are about 7 times longer than the above-ground part of the plant.

Lesson number 1

Type of lesson:   lesson discovery of new knowledge

Forms of work organization:frontal, individual, conversation, work in pairs (laboratory work)

Methods:   verbal (conversation); visual (work with drawings, diagrams); practical (exercise, filling out schemes, laboratory work); deductive (analysis, application of knowledge, generalization).

The purpose of the lesson: study the structure of seeds, identify the structural features of seeds of dicotyledonous plants, find out the importance of seeds for plants as an organ of its reproduction and distribution.

Tasks of the lesson:

Educational:

Know the structure of the seed;

Identify common and distinctive features in the structure of seeds of dicotyledonous plants;

Recognize and describe the structure of seeds of dicotyledons by drawing;

Establish a correspondence between parts of the seed and organs of the seedling;

Call the value of the seed;

Continue the formation of the learning skills of laboratory research.

Developing:

Establish cause and effect relationships;

Compare by the proposed criteria seeds of dicotyledonous plants;

Develop memory, speech, the ability to highlight the most important, generalize, draw an analogy and comparison.

Educational:

- continue the formation of skills to work with natural objects, compare objects, inculcate practical skills and abilities to recognize and identify seeds, the ability to work with a textbook, the ability to exercise self-control;

Consciously achieve the goal.

Planned educational outcomes:

Subject results:

Define the concepts studied: embryo, endosperm, cotyledon, class monocotyledons and dicots, seed coat, micropyle;

Identify the distinctive features in the structure of monocot and dicot seeds.

PERS:

To be aware of the incompleteness of knowledge, to show interest in new content;

Establish a link between the purpose of the activity and its result;

Compliance with the requirements of TB when working with laboratory tools.

Meta-Subject Results:

Educational ccd:

Learn: to establish cause-effect relationships in the studied topic;

Use information from the textbook, other sources about the structure of seeds of different plants;

The practical application of knowledge: the study and description of dry and swollen seeds of beans, using the guidance card work.

R regulatory ECM:

Independently determine the purpose of learning activities, look for ways to solve the problem and the means to achieve the goal;

To participate in the collective discussion of the problem, to be interested in the opinions of others, to express one’s own;

Adequately perceive the assessment of their work as a teacher, comrades.

Communication uud:

Will get the opportunity to apply: skills and experience of interpersonal communication, correct dialogue and participation in the discussion.

The ability to engage in dialogue and participate in a collective discussion of the problem, to argue their position;

Use different information resources to search for information.

Equipment for the lesson:

1. Multimedia projector, computer, screen, presentation “Seed structure of dicotyledonous plants”.

2. Textbook V.V. Beekeeper

3. Individual cards (with text, test).

4. A set of laboratory glassware and equipment (Petri dishes, laboratory needles), germinated and dried beans, manual magnifier.

Basic concepts:   embryo, endosperm, cotyledon, class monocotyledonous and dicotyledonous, seed coat, micropile

Technological map of the lesson: "The structure of the seeds of dicotyledonous plants»Grade 6 (teaching materials, edited by V. Pasechnik, line" Vertical ")

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