Presentation on biology life cycles of reproduction. Full development of the lesson on the topic "Life cycles" (Grade 8)

slide 1

Forms of reproduction of organisms. The life cycle of organisms and the nature of the change of generations

slide 2

Characteristics of sexual and asexual reproduction Forms of reproduction Which cells are involved Genetic information changes Genetic information does not change Diploid chromosome set Haploid chromosome set

slide 3

Characteristics of sexual and asexual reproduction Forms of reproduction Which cells are involved Genetic information changes Genetic information does not change Set of chromosomes diploid Set of chromosomes Haploid Asexual Somatic + + Sexual Sexual + +

slide 4

Asexual reproduction Division Spore formation Budding Fragmentation Vegetative Polyembryony

slide 5

Forms of asexual reproduction 1. Division. The oldest and simplest form of asexual reproduction. Reproduction by cell division is characteristic of unicellular organisms. There are two main methods of division - binary division - a division in which two equivalent daughter cells are formed; multiple division, or schizogony - a division in which the mother cell breaks up into a large number of more or less identical daughter cells (malarial plasmodium); multiple fission is divided into two phases: a nuclear fission phase; phase of cytoplasmic division.

slide 6

Forms of asexual reproduction 2. Sporulation. Reproduction through spores - specialized cells of fungi and plants. As a rule, spore formation occurs in sporangia - unicellular or multicellular structures. If the spores have a flagellum and are mobile, then they are called zoospores (chlamydomonas). But spores can be formed as a result of sexual reproduction, as, for example, occurs in cap mushrooms.

Slide 7

Forms of asexual reproduction 3. Budding. A method of reproduction in which an outgrowth is formed on the mother individual - a kidney, from which a new individual develops. Moreover, the daughter individual can either separate from the parent and move on to an independent lifestyle (hydra), or remain attached to it, then a colony is formed.

Slide 8

Forms of asexual reproduction 4. Fragmentation Fragmentation is the division of an individual into two or more parts, each of which develops into a new individual. This method of reproduction is observed in both plants and animals (annelids). Fragmentation is based on the property of regeneration - the ability of some living beings to restore lost organs and tissues.

Slide 9

Forms of asexual reproduction 5. Vegetative reproduction. A form of asexual reproduction characteristic of many plant groups. During vegetative propagation, a new individual develops either from a part of the mother or from special structures (bulb, tuber, etc.) specially designed for vegetative propagation.

slide 10

Forms of asexual reproduction 6. Polyembryony. Represents reproduction during embryonic development, in which several embryos develop from one zygote - twins (identical twins in humans). Offspring are always of the same sex.

slide 11

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Slides captions:

sexual reproduction

Sexual reproduction Distinguished by the presence of a sexual process Occurs with the participation of haploid germ cells - gametes Gametes are formed in special organs of male and female individuals The genetic material of the parent individuals is combined, resulting in an increase in the genetic diversity of the offspring and its vitality

Biological species depending on the cells produced Dioecious females, males Bisexual hermaphrodites

Male reproductive system Female reproductive system

Male reproductive system Internal testes vas deferens Seminal vesicles Prostate gland External penis Scrotum

Male reproductive system Testis Deferent duct Sperm Prostate Urethra Mature spermatozoa Human spermatozoa are about 0.005 mm wide, 0.06-0.07 mm long, and weigh 0.000000005 g. 1 cm 3 of sperm contains from 20 to 60 million spermatozoa. mps

Human germ cells acrosome

Female reproductive system Internal ovary Fallopian tubes Uterus Vagina External labia

Ovaries Mature egg Fertilization Vagina Oviduct Uterus Fallopian tubes The diameter of the egg is 0.15 mm, the weight is 0.000003 g. The female reproductive system The ovary of a newborn girl weighs 0.2 g and contains about 400,000 immature germ cells.

Human germ cells

The structure of germ cells Signs Female gametes Male gametes Shapes and sizes Structural features Number of chromosomes Main functions

Find a match: Concepts Categories Content of the concept 1. reproduction 8. cell 13. reproduction of their own kind 2. eggs 9. process 14. fusion of germ cells 3. spermatozoa 10. organ 15. formed in the ovaries 4. fertilization 11. gland 16. intended for gestation 5. testes 12. body 17. produces eggs 6. uterus 18. produced in testes 7. ovaries 19. produces spermatozoa

On the topic: methodological developments, presentations and notes

Lesson development for 6th grade. Presented work in groups. During the lesson, all students in the class answer at the blackboard ....

, Biology

Class: 10

The lesson is recommended to be held in the 10th grade (profile training) after studying the topics “Cytology”, “Reproduction and development of organisms”. Lesson-theoretical seminar is held on a modular technology with a wide coverage of students' knowledge: from the courses "Plants", "Animals" and the basics of the structure and life of the cell. The duration of the lesson is 90 minutes (2 academic hours). The main methodological goal of the lesson: systematization and generalization of students' knowledge and the formation of the concept of "Life cycle".

Preparing for the lesson. The teacher prepares preliminary assignments: algorithms for preparing differentiated homework assignments for groups ( Annex 1) .

There is also a corresponding change in mitosis and meiosis: sporophyte (diplophase) - meiosis - spores - mitosis - gametophyte (haplophase) - mitosis - gametes - zygote - mitosis - sporophyte (diplophase).

In order to find out other ways of alternating nuclear phases, the life cycles of a frog (class Amphibians) are considered. annex 5, slide 9) and the life cycle of Chlamydomonas ( annex 5, slide 7), the life cycle of gymnosperms on the example of Scots pine ( annex 5, slide 8).

As a result of the discussion, it turns out that there are the following types of nuclear phase change in the life cycles of different organisms:

life cycle with intermediate reduction of nuclear phases

(in most plants);

life cycle with gametic reduction of nuclear phases(in most multicellular animals);

life cycle with zygotic reduction
(in unicellular organisms).

The last group covers the life cycle of the malarial plasmodium in order to clarify the alternation in the life cycle of various methods of reproduction. After the presentation of the group, students draw up schemes for alternating breeding methods, using diagrams of the life cycles of jellyfish and chlamydomonas ( slides 11,12 appendix 5 ).

Thus, the life cycle is a change of a different number of generations, which are repeated in a certain sequence as a result of different methods of reproduction.

Independent work is carried out with the aim of generalizing and consolidating the patterns identified in the study of the life cycles of various organisms. According to the proposed algorithm, students perform work and voice the results of work in front of the class (Annex 1 life cycles of the liver fluke and representatives of the Scyphoid class) ( annex 5slide 13 ).

Generalization is carried out according to generalizing schemes. ( annex 5slides 14-16 ). Generalizing schemes can be compiled by the students themselves in groups in the course of independent work. To activate the work in this case, they can be offered terms, silent drawings, unfinished diagrams. The degree of assistance provided depends on the preparedness of the students. If you are sure that the students of this group can cope with the proposed work, they can be offered the topic of a generalizing scheme. For example, when teaching this lesson, I usually suggest the following topics:

draw up a general scheme of the life cycle with zygotic reduction of nuclear phases,
draw up a generalized scheme of the life cycle with an intermediate reduction of nuclear phases,
draw up a generalized scheme of the life cycle with a gametic reduction of nuclear phases.

Or a generalizing scheme is offered by the teacher. Naturally, this depends on what goals the teacher pursues when working at this stage of the lesson. .

In order to check the level of assimilation of the studied material, knowledge control is carried out before summing up the lesson. (appendix 5, slides 17-21). Students are offered 4 options for tasks (Appendix No. 3).

The generalization of knowledge according to generalizing schemes and the implementation of final control with individual cards in one lesson can only be used if the students know the material very well and the minimum part of the study time is spent on the first part of the lesson. In my practice, I use different options. The main thing is that the lesson brings maximum satisfaction to both the teacher and the students and the goal is achieved.

Another option for summarizing is that the leaders of the project teams prepare a publication - the booklet "Life Cycles" and present it as their creative work. (Appendix 4).

In the final part of the lesson, the results are summed up and marks are given.

Literature

M.B. Berkinblit, S.M. Glagolev, V.A. Furalev General biology. MIROS M, 1999
G.P. Yakovlev, L.V. Averyanov Botany for teachers, M. Education. 1996
N.V. Chebyshev, S.V. Kuznetsov, S.G. Zaichikova Biology Handbook for applicants to universities. M. New Wave 2004.
ON THE. Krasilnikov, A.A.Uranov Encyclopedia Plant Life. M Enlightenment 1974
Yu.I. Polyansky Encyclopedia of Animal Life. M. Education 1987.
THEIR. Sharova Zoology of invertebrates

Goals

Educational: to form knowledge of the life cycles of living organisms; to reveal the concept of reproduction, its role and features;
Developing: continue to form the ability to work independently with literature and additional sources, develop the ability to creative and logical thinking, the ability to concisely express one's thoughts;
Educational: fostering a healthy lifestyle, increasing interest in the biological sciences.

Tasks

1. Expand the concept of the life cycle.
2. Consider the phases of the life cycle
3. Determine the importance of reproduction in the life of organisms.
4. Consolidate the educational material by completing practical tasks.

Terms and concepts

The life cycle is a set of processes carried out from the moment the needs of society for a certain product are identified to the moment these needs are met and the product is disposed of.
Reproduction is the inherent property of all living organisms to reproduce their own kind, ensuring the continuity and continuity of life.
Fertilization- this is the fusion of a male reproductive cell (sperm) with a female (egg, ovum), leading to the formation of a zygote - a new unicellular organism.
An embryo is a living organism in its early stages of development.

During the classes

Knowledge update

Answer questions
1. What is life?
2. What is a living organism or individual?
3. What do you think "reproduction" means?
4. What are the types of reproduction that you know from previous biology courses?
5. What kind of reproduction is inherent in man?

Learning new material

All living things in our world have their own logical chain - birth, youth, maturity and death. This applies to a plant, to an animal, to a person or an insect - for a different period of time, all living things go through these stages. In other words, it can be called a mandatory alternation of life cycles.

It ensures the safety of species, the ability of living organisms to reproduce. What is reproduction, you can learn from the terms given at the beginning of the lesson. Write these terms in your notebooks.

reproduction is a complex process, specific for each type of living organisms. But there are 2 types of reproduction - sexual and asexual.

Sexual reproduction can occur if there are male and female organisms. Accordingly, these organisms must contain in their anatomical structure the corresponding reproductive systems. Figures 1 and 2 show, respectively, the structure of the male and female reproductive systems.

Rice. 1 The structure of the male reproductive system

Rice. 2. The structure of the female reproductive system

The male reproductive system produces the male sex cells necessary for reproduction - spermatozoa. Women's - an egg.
Look at Figure 3 - it shows the male and female sex cells:

Rice. 3 The structure of the sperm and egg

Exercise. Sketch in your notebook a diagram of the structure of the female reproductive cell and the male.
The structure of the spermatozoon is shown in more detail in Figure 4.

Rice. 4 The structure of the spermatozoon

It is important to note that the violation of the structure of sperm leads to the inability to fertilize. That is, cells with structural defects are sterile. You will see an example of a violation of the morphology of spermatozoa in Figure 5.

Rice. 5. Violations of sperm morphology

The following video shows the principle of the male reproductive system

Now look at figure 6 - it schematically displays data on the female reproductive system. Take a good look at the diagram and draw it in your workbook.

Rice. 6. Female reproductive system

To better understand the structure of the female reproductive system, watch the video

When a haploid egg is fertilized by a haploid sperm, a new living organism is conceived. As a result of fertilization, a germ cell is formed - a zygote - with a complete (that is, double) set of chromosomes. In humans and animals, an unborn living organism is called an embryo. The formation of the embryo occurs mainly in the intrauterine period. After birth, the young organism only develops and grows. That is, all vital organs and systems are laid down before birth.

It is important to note that the new organism receives a set of chromosomes from its parents equally.
You can best understand reproduction and fertilization with the help of the following entertaining video:

Consolidation of knowledge

Answer tests:
1. Reproduction is divided into:
A) sexual and asexual
B) sexual and vegetative
C) vegetative and budding.
2. For sexual reproduction, you need:
A) a healthy body
B) the presence of a male and female body
C) the presence of only a female body
3. The male germ cell is:
A) egg
B) testosterone
B) sperm
4. Female germ cells mature in:
A) ovaries
B) testicles
B) fallopian tubes
5. The zygote has a set of chromosomes:
A) haploid
B) diploid
C) depending on the temperature regime n or 2n.

1. Name the organs of the female reproductive system.
2. Define "reproduction".
3. Name the function of reproduction.
4. Describe the life cycles of a person.

To consolidate the studied material, watch the following video again:

Homework

1. Process the textbook material - paragraph 60.
2. Draw in your notebook the structure of the egg and sperm.
3. Learn the terms given at the beginning of the lesson.
4. Prepare reports on the topic "Human life cycles", "Animal life cycles" (optional)

Bed bugs mate by traumatic insemination. This means that the female, in principle, does not have a genital opening, and the male has to pierce her abdomen with his genital organ, introducing sperm there.
- Giant pandas are recognized as an endangered species and have a low birth rate. Female giant pandas are ready to breed only once a year for 72 hours, and only 12 to 24 hours in this period they can be successfully fertilized. Males, on the other hand, have disproportionately small penises, which is why sexual intercourse is possible only in a strictly defined position, and males know this position poorly.
- The offspring of seahorses is carried by the male, not the female. On the body of the male there is a special pocket where the female throws eggs. This brood chamber is richly supplied with blood and acts as a uterus.

List of sources used

1. Lesson “Life cycles. Reproduction "Pozdnyakov.A.P., teacher of chemistry, biology, secondary school No. 8, St. Petersburg
2. Lesson “Reproduction. Features of sexual reproduction "Latysh I.S., teacher biology School No. 207, Moscow.
3. Lesson "Human sexual reproduction" Shepel K.A., biology teacher, secondary school No. 58, Donetsk
4. Kolesov D.V. etc. Biology. Person. Textbook for grade 8. (3rd ed.) - M.: Drofa, 2012. - 336 p.
5. Omelkovets Ya.B. Biology. Test tasks. Grades 6-11 - K .: Academy, 2011. - 444 p.

Edited and sent by Borisenko I.N.

Working on the lesson

Borisenko I.N.

Pozdnyakova A.P.

Latvian I.S.

Shepel K.A.

You can raise a question about modern education, express an idea or solve an urgent problem at

Lesson 64: Life cycles. Reproduction.

Goals:

Educational: give a concept of the life cycles of individual individuals and the conditions for the existence of the species;to reveal the concept of reproduction, its role and features; identify the advantages of sexual reproduction over asexual reproduction in adaptation to the environment; introduce the male and female reproductive systems, the formation and development of the fetus, the causes of menstruation and wet dreams.

Educational: fostering a healthy lifestyle, increasing interest in the biological sciences.

Developing: continue to form the ability to work independently with literature and additional sources, develop the ability to creative and logical thinking, the ability to succinctly express one's thoughts.

Equipment: tables "Scheme of fertilization and development of the embryo", "Male reproductive system", "Female reproductive system".

Lesson type: combined.

During the classes.

Organizational moment.

Knowledge update.

Individual survey on matters after §59 or:

To reveal the role of the pituitary gland in the regulation of growth and development.

Tell about the meaning and functions of the thyroid gland and the consequences of their violations.

To highlight the significance of the endocrine glands in the individual development of the organism.

Find out the role of the adrenal glands in the adaptation of the body to increased stress.

Goal setting and motivation.

People often ask themselves the question: “Why did we come into this world? What is the purpose of man on this earth? Work? To study? Travel?"

From time immemorial, man has been worried about another question about the immortality of the soul and body. How many recipes for eternal existence, elixirs of youth have been invented, but to this day the problem remains unresolved. Many smart minds have worked to answer these questions.

The answer lies in the powerful instinct inherent in all living things - to leave behind offspring. Our children are a part of ourselves and our parents too. As long as children are born, then we are immortal, because they contain the genes of our kind.

So, the topic of today's lesson is “Life cycles. Reproduction".

The Lord said "Be fruitful and multiply" (in the great book "Bible") and he did everything for this. There are many wonders of the world in the world, but one of them, in my opinion, is the most perfect creation - the human body (photos of paintings and sculptures of a person made by various artists). Everything is beautiful in it, there is nothing shameful, and many poets and artists glorified the beauty of the human body.

Learning new material.

Life cycle is a set of processes performed from the moment the needs of society for a certain product are identified to the moment these needs are met and the product is disposed of.

Give an answer to the questions:

What is life?

What is a living organism or individual?

What do you think "reproduction" means?

The root "multiple" in the word "reproduction" indicates that this process is aimed at increasing the number. This is one of the fundamental properties of living things - the reproduction of their own kind.

Even the smallest non-cellular structures - viruses, albeit not independently, but with the help of the host cell, also multiply. In the course of evolution over billions of years, several main ways or methods of reproduction have arisen in nature.

reproduction - the inherent property of all living organisms to reproduce their own kind, ensuring the continuity and continuity of life.

What are the types of reproduction that you know from previous biology courses?

reproduction

asexual sexual

Fission Spores Vegetative

RT assignments No. 220-221.

What is the most common way of reproduction in nature, both in plants and in animals?

Why is the sexual method of reproduction more progressive in the organic world?

The change of generations of people is associated with reproduction, which is characteristic of all living things, however, unlike representatives of the animal world, people have a highly developed consciousness and try to build their families on the basis of mutual love and raise children.

Sexual reproduction can occur if there are male and female organisms. Accordingly, these organisms must contain in their anatomical structure the corresponding reproductive systems.

The male reproductive system produces the male sex cells necessary for reproduction - spermatozoa. Women's - an egg.

For the first time, a human spermatozoon was seen in 1677 by A. Leeuwenhoek, and in 1853 the penetration of spermatozoa into the egg was described. Research author F. Keber.

Out of 100 million sperm cells, only 1 fertilizes the egg.

The cycle of sperm formation is 70-75 days.

The path of the sperm along the vas deferens is 10-15 days.

In the air, the sperm cell lives 24 hours, in the body of a woman - 3-4 days.

In all cases, the eggs are large and inactive, and the spermatozoa are small, mobile, consisting of a head, neck and tail.

Eggs carry a set of X chromosomes, while sperm carry either X or Y chromosomes. If XX chromosomes merge, a girl is born, XY - a boy.

It is known that the number of chromosomes in different representatives of the kingdom Animals is different, for example, the hydra has 32, the rabbit has 44, and the cockroach and chimpanzee have the same number - 48!

It is important to note that the violation of the structure of sperm leads to the inability to fertilize. That is, cells with structural defects are sterile.

Each human cell has 46 chromosomes. In an egg (a fertilized female germ cell) there are also 46 chromosomes.

Why are there 46 chromosomes in the egg, and not 92, because the egg is formed as a result of the fusion of two (male and female) germ cells?(Sex cells have half (haploid) set of chromosomes compared to somatic cells (have a diploid set of chromosomes))

- this is the fusion of a male reproductive cell (sperm) with a female (egg, ovum), leading to the formation of a zygote - a new unicellular organism.

During intercourse, spermatozoa quickly penetrate the female genital tract into the upper part of the uterus, and out of several million, only one penetrates the egg. That's how we got to you. So we are initially Winners, because millions of other applicants could be born.

A fertilized egg - a zygote - begins to divide and descend into the uterus, where it is introduced into its mucous membrane and over time a placenta (children's place) is formed, through which the embryo is nourished. It is a disk 20 cm in diameter and 5 cm thick, intertwined with the blood vessels of the mother and child, but they are not united.

In humans and animals, an unborn living organism is calledembryo . The formation of the embryo occurs mainly in the intrauterine period. After birth, the young organism only develops and grows. That is, all vital organs and systems are laid down before birth.

Differentiation of the genital organs into male andfemale in humans is completed by the 8th week of internalintrauterine development.

Two people participate in the prolongation of the family: a man and a woman, and everything is provided for this in their body. They differ from each other externally, as well as the structure of the reproductive organs.

reproductive system

Sex organs

Men's

Women's

outdoor

scrotum

penis

urethra

large labia

labia minora

clitoris

vestibule

Internal

testicles

vas deferens

spermatic cord

prostate

Cooper's gland

ovary

uterus

oviduct

vagina

Acquaintance with the structure and functions of the human reproductive systems occurs in the process of independent work with the textbook §60 p.308-310 and the fulfillment of task No. 223 in the RT.

Menstruation - monthly process of rejection of the endometrium, accompanied by the release of blood.

pollution - involuntary release of sperm.

Primary fastening.

Answer tests:

1. Reproduction is divided into

A) sexual and asexual

B) sexual and vegetative

C) vegetative and budding.

2. For sexual reproduction, you need:

A) a healthy body

B) the presence of a male and female body

C) the presence of only a female body

3. The male germ cell is:

A) egg

B) testosterone

B) sperm

4. Female germ cells mature in:

A) ovaries

B) testicles

B) fallopian tubes

5. The zygote has a set of chromosomes:

A) haploid

B) diploid

C) depending on the temperature regime n or 2n.

1. Name the organs of the female reproductive system.

2. Define "reproduction".

3. Name the function of reproduction.

4. Describe the life cycles of a person.

Homework assignment.

§60, terms after paragraph.

RT assignment No. 222

Reflection.

Interesting to know that...

Giant pandas are recognized as an endangered species and have a low birth rate. Female giant pandas are ready to breed only once a year for 72 hours, and only 12 to 24 hours in this period they can be successfully fertilized. Males, on the other hand, have disproportionately small penises, which is why sexual intercourse is possible only in a strictly defined position, and males know this position poorly.

Seahorse offspring are carried by the male, not the female. On the body of the male there is a special pocket where the female throws eggs. This brood chamber is richly supplied with blood and acts as a uterus.

About male sex cells

The average volume of one human spermatozoonequal to 16–19 µm 3 . During the day in the testesA human matures up to 100 million spermatozoa.

Number of chromosomes in some types of organisms

Sunflower

Potato

Cucumber

Apple tree

Earthworm

Drosophila

Rabbit

Person

About Barr bodies

One of the methods that played an important role in the study of the problem of sex in humans is the detection in the nuclei of human cells and some other mammals of special chromatin formations, known by a double name, namely: sex chromatin or Barr bodies (after the author who discovered them in 1949 G.).

Barr bodies are spherical formations about 1 micron in diameter; they are located near the wall, adjacent to the inner surface of the nuclear envelope. The chromatin nature of Barr bodies is evidenced, in particular, by the fact that they are stained with the same special dyes as chromosomes.

The origin of Barr bodies and their relationship to chromosomes will be discussed below. For now, we will note their other important feature, which is that they are found only in female somatic cells (i.e., in female animals and in women) and are absent in male somatic cells (i.e., in male animals and in men).

We give preference to the name “Barr bodies” because, firstly, it goes well with numerals, which cannot be said about “sex chromatin” (for example, “two or three Barr bodies”, but not “two or three sex chromatins” ), and, secondly, it more accurately expresses the meaning of the concept, since the nature of the Barr bodies (sex chromatin) is the same, regardless of their number.

In the nuclei of normal females and in women, one Barr body is found. Barr bodies were not found in ovogonia.

In addition to humans, Barr bodies have been found in monkey, cat, dog, mink, marten, ferret, fox, bear, wolf, goat, deer, raccoon, skunk, coyote, pig, cow, and opossum. In rabbits and rodents, including the mouse, which has been most extensively studied in all respects, Barr bodies cannot be found.

Microscopic examination of the cells of an animal of any of the named species or a person for Barr bodies makes it possible to determine its sex, so to speak, behind the eyes, without seeing the object of study itself. From this it is clear how important this nuclear “mark” has become in the analysis of human sexual types. The analysis for Barr bodies can be done easily, quickly and with a fairly reliable result, not only in adult humans and animals, but, if necessary, in the early stages of intrauterine development of the human fetus. In adults, a piece of skin or a scraping from the mucous membrane of the oral cavity is taken for analysis (most easily from the cheek); in practical work, this last method is used, as the simplest.

Thus, modern researchers have two mutually complementary methods for clarifying certain aspects of the problem of sex in humans: one of them is a direct count of the number of chromosomes and its deviations from the norm, the other is the study of Barr bodies. Both of them played an important role in clarifying the mechanism of sex determination and the causes of aberrant sexual types in humans.

From the book of N. N. Medvedev "Conversations on the biology of sex"