Plant development cycles EGE scheme. Gamenaophyte and sporophyte

13.08.2020

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1. Determination of ontogenesis

The first higher plants occurred from green algae (living in fresh or weakly saline water) and largely depended on the presence of water at all stages of the life cycle. For all primitive higher plants, fertilization in the aquatic environment is characterized. For rhinofitis - ancient, long-dimensional group of primitive higher plants - are characterized by many signs of similarities with algae both in the external and internal structure and in the peculiarities of the life cycle.

In the future, the evolution of higher plants was aimed at an increase in adaptability to the ground medium (the appearance of conductive, coating and mechanical tissues, the formation of root and shooting systems, the appearance of mycorrosis, the gradual complication and lengthening of the diploid phase - generation of sporophyte).

Higher plants mostly live on land, i.e. In principle, other conditions compared with algae (lower plants). When the first plants went to the land (approximately 400 million years ago), they were immediately forced to adapt completely to other environmental modes. All environmental factors meaningful for plants are changed much in large limits than in the aquatic environment.

By virtue of the larger diversity of the ground medium compared with the water, terrestrial plants are much more complicated and more diverse compared to algae. The number of types of ground organisms (including representatives of all kingdoms) is 5 times more than aquatic organisms. The highest, mostly terrestrial, plants are known about 300 thousand species, and the lower (algae) are about 3 thousand species.

Under the life, or general, the development cycle of plants understand their ontogenesis - the individual development of the plant from its occurrence from the fertilized egg or vegetative kidney to natural death. As a process, ontogenesis consists of a number of consistently advancing age periods, or stages: embryonic, juvenile, virgin, generative and old age.

The embryonic stage begins on a maternal plant with the formation of zygota - fertilized egg. As a result of the processes of division, growth and differentiation of cells from the zygota, a germ of seed is formed. It is characterized by a heterotrophic power method.

The juvenile stage begins with the germination of the seed, which means not only the fixation of the new plant organism in a certain place of the phytohosphere (the vegetation cover of the Earth), but also the transition to the autotrophic method of nutrition.

Varginium stage - transition of plants to the formation of photosynthetic organs typical of an adult plant. Since at this stage of the plant has a very strong vegetative growth (i.e., the growth of vegetative organs), but are not capable of forming the generative bodies, the virgininal stage is often called the growth phase and the virgin period.

The generative stage is characterized by the ability of plants to education in addition to the vegetative organs also generates: micro- and macrostaturbs (i.e., male spikelets and women's shishchets) in the vicered, flowers are coated, with subsequent formation as a result of pollination and fertilization of cones (vote), Frucil (coated) and seeds. Life cycle Higher plants consist of two phases (or generations) - cruel, or sporifase (sporophyte), and sexual, or gamingophase (Gametophyte).

2. Life cycles of plants

The life cycle of higher plants consists of two rhythmically alternating phases, or "generations" (Fig. 1), - sexual (gametophyte) and the crucible (sporophyte). Sexual organs develop on Gametophyte. Gamenaophyte can be routine. In this case, it develops both and surias and Archegonia. But the overwhelming majority of higher plants (including all vote and flowering plants), it is one-sex and carries or only Aniardia (Male Gametofit), or only Archegononia (Female Gametofit). As a result of fertilization, i.e., the mergers of the male gamete with the female, a new cell is formed with a double set of chromosomes (paternal and maternal), called the zygote.

At the highest plants, in contrast to the lower, the zygota gives rise to a multicellular germin. As a result of growth and differentiation of the embryo, sporophyte develops. Like the zygote, all the cells of the embryo and the developing sporophyt are characterized by a double chromosome.

The spores are formed by sporangies in which disputes develop are very small, usually barely distinguishable with uninimited unicellular formations that serve for crucible reproduction. When forming a dispute, the number of chromosomes as a result of meiosis is doubled, and therefore each dispute with respect to sporophyte cells is a haploid.

Many of the highest plants, for example, in most ferns, each dispute gives rise to a hawmetophyte rim, which is developing both and surriad and Archegononia. However, most of the highest plants have sporangies of two types: microsporegia, which forms smaller microspores, and megasoprangies in which larger megasy develop. Each Microspore gives rise to one male gameman, and from each megasport is formed on one female gametophyte. Therefore, some authors, for example, B. M. Kozo - Polyansky, are called microspores by "male disputes", and megasy - "female disputes". On men's Gametofith, only Aniardia are developing, and on the female - only Archegononia.

Both sexual and the use of breeding shapes have certain biological advantages. With sexual reproduction, a combination of hereditary material of parental forms is achieved. An individual formed during sex reproduction is not a one of its parents. The sexual process provides recombinant genetic variability of organisms from generation to generation, so sexual reproduction gives the mind advantages implemented with natural selection.

Under the bunch of reproduction, hereditary features are transmitted unchanged and can be easily fixed in a number of generations, while the hereditary material of the parent individual is "replicated" and a rapid increase in numbers is possible. However, most often in plants are precisely alternation of sexual and minerals.

In all higher plants, except for mugh-like, spores prevail in the life cycle, the Gametophyte is developed weaker and relatively short-lived. Sporophytes are large multicellular organisms with a complex anatomical structure and body dismemberment to organs - stems, leaves, roots (real or apparent).

Thus, the full life cycle of the highest plant from the zygota to the zygota consists of Gamenophase (Gametophyte) and sporifase (sporophyte). Due to this, in the life cycle of the highest plant, a kind of "dual personality" manifests itself, and more than two different forms. In many higher plants (plauines, horsages and ferns), these phases are as part of individual physiologically independent creatures. Movu and especially in seed plants, one of two generations is coented with another and in physiological from wearing, as it were, reduced to his body. But although they have a physiologically, they ceased to be here with separate generations (independent beings), according to their origin, they fully comply with them, and the terms "Gametofit" and "sporophyte" can be used to them.

3. Lower plants (talomous, layers)

Lower plants whose body is not divided into organs and fabrics; It may be unicellular, colonial, multicellular. Sectional reproduction bodies (oogonium and antheridia) and sporangia are unicellular.

Department of Algae.

Algae - lower plants inhabiting predominantly water medium - flowable, standing, marine saline and fresh reservoirs. Algae can live on land in the water film. These are mainly soil algae and algae, inhabitants on other plants.

Size: 25 microns - 50 m.

There are no real tissues, vegetative organs. AutoTrophic. Spare substances - starch, oil.

In cells there are all organelles typical for vegetable cellbut pigment carriers are not plastdoms, but chromatophores (in which there is, except chlorophyll, pigments of blue, red, brown, yellow, which complement orange-red sections sun raynot passing through water beast, which allows the algae to dwell at high depths). Their body is one or colony of cells. The body is not divided into organs and fabrics.

The reproduction occurs in a trembling, cullless or sex merger.

Division of lichen

Lichens are a group of lower symbiotic organisms, the body (layer) of which consists of two components:

1. Auto-flow (alga, cyanobacteria, protists) - supplies mushroom with organic substances created during photosynthesis.

2. Heterotrophic (mushroom) - supplies water with dissolved mineral salts, protects the autotrophic organism from drying out.

The complex nature of lichens allows them to be powered not only from the soil, but also from air, atmospheric precipitation, moisture of dews and fogs, dust particles deposited on layers. Therefore, lichens have a unique ability to exist in extremely unfavorable conditions, often completely unsuitable for other organisms, - on bare rocks and stones, roofs of houses, tree crusts, and even glass.

The vegetative body of lichens is entirely consisting of interlacing mushroom hyphae, between which algae are located.

Most lichens, dense plexuses of mushroom threads form upper and lower cortical layers:

under the top cortex layer is a layer of algae, where photosynthesis is carried out and organic substances accumulate.

below is the core consisting of loose gifs and air cavities. The heart function is air to conduct air to algae cells. The walls of the mushroom cells are perforated, and the cells are connected by cytoplasmic bridges. Gift shells are thickened, providing mechanical stability of the layer. Many lichens gifs may be touched. Lichetic mushrooms also have fat gifs in places of attachment to substrate.

The lichen is inherent in biological properties that have no mushroom and algae taken separately when the mushroom provides algae with water and mineral salts, and uses organic substances synthesized by algae.

More than 20 thousand types of lichens are known.

Lichen layers are usually gray, light or dark brown. Their age reaches dozens and even hundreds of years.

Lichens are widespread, are pioneers in the development of scuba habitats.

Characterized slow growth. By virtue of the extremely low speed of accumulation of organic matter, the annual increase in the layers is small and averages 0.5-- 0.7 mm per year.

Depending on the structure, external view Layers allocate several types: scuffed lichens, sheets of lichen, bushy lichens. The reproduction of lichen occurs mainly, vegetative pathways - pieces of layers and disputes that forms mushroom

Lichens are so peculiar group of living organisms that researchers still have no consensus on their position in the system of organic world.

4. Higher plants

The highest plants include the development of which is accompanied by the formation of the embryo, and the body is disseminated on the stem, root and sheet. These are complex multicellular organisms whose cells are differentiated and form various tissues. Archegonia and Aniardia multicellular (or reduced), multicellular sporangies.

Appeared on Earth as a result of the exit to the land of algae in the Silurian period of the Paleozoic era.

Ground higher plants are presented:

spore: Mossoid, rhinofitoid, plane-shaped, flange, fern

Department of Rynofiti

The remains of rhinofitis were first discovered in 1859 by the Canadian geologist James Dovon in Devonian sediments. According to the original ideas, for the first time appeared in the silver (415 - 430 million years ago). Nakhodka was named Psilophyton Princeps (Gasos Primary). Later, the remains of similar plants (Big Rini) were found in Scotland near the der. Raine is from here and the name of the department. Rhinofitis is the first terrestrial plants, externally more similar to algae than on top plants. For them, it is characteristic:

dichotomic branching

lack of leaves

primitive conductive system

terminal (top) sporangies

equipment

availability of Archegan and Anteridiev

no mechanical tissue

mikoriza

Representatives of rhinofitis are also the Teniocrad (perhaps water plant), Jarai and others.

From rhinofitis or plants close to them, all other higher plants occurred (apparently, except for Mids, which, most likely occurred directly from green algae).

Department of Mossoids

A separate group of plants, which is studied by Briology - Science of Moss. There are about 25,000 species (Russia and neighboring countries - about 1,500 species). Known mosses in the fossil state.

Mossi is the only evolutionary line in the plant world associated with the regressive development of sporophyte. Usually, MAs are considered a dead-end, blind branch of plant development. Nevertheless, the MAYs set up wet habitats very long ago, firmly occupied a place in nature and retain this place for many years, despite climate change, soils and vegetation cover.

Characteristic signs of moss:

low perennial plants from 1 mm to 60 cm high;

the body can be represented by a layer or divided into leaves and stem;

no roots, suction occurs in most MShs with the help of rhizoids - epidermis growth, or through pores in cells (sphagnum mosses);

monodomal or downtime plants;

separed fabrics appear, better expressed in leafy forms (assimilant, mechanical, conductive);

in the life cycle, the haploid and diploid generation alternate, the haploid gametophyte prevails;

the diploid generation of MSh is called a sports; It is a box with disputes (spots) on the leg;

the lower part of the leg forms a suction cup (Gautory), which is introduced into the body of the gametophyte;

the sports is devoid of independence and completely depends on the Gametophyte.

Photosynthesis productivity is 40-50 times less than in flower;

Low enzyme activity;

Small chloroplasts contain 5-10 times less chlorophyll than flowering;

For photosynthesis, 4% of full illumination is enough;

Can absorb carbon dioxide in the dark and translate it into organic compounds;

Tundra species and all liver mosses photosynthesis is possible at -14 ° C

Mossi - causticohydric plants absorb water in physical laws (capillary, swelling, hygroscopicity) and depend on the humidity of the medium. Active absorption of water is possible.

In adverse conditions, theabiosis (all metabolic processes practically cease); Can carry moisture deficit, high (up to 70 ° C) and low temperatures.

Many species - oligotrophs (undemanding to soil conditions).

The ability of moss is normally photosynthesize with weak lighting, actively absorb water from the soil and atmosphere, grow in extreme conditions and to fall into the anabioz state allows them to avoid competition from more specialized plants.

Mossoid life cycle:

Many mughters can multiply vegetatively for a long time.

With sexual reproduction on Gametofith, genitals are developing - men's attachments and female Arhegonia.

Numerous usually wind-making movable spermatozoa in water reaches a stationary egg, located at the bottom of Archegononia. Fertilization occurs, and directly inside Archegonony is formed by diploid zygote.

From the zygota, the diploid sporefield is beginning to develop, which is a box on the leg. From above, the box can be covered with a cap formed from Archegononia.

The growing sporophyte grows on Gametophyte and feeds often at the expense of it. In a box of sporophyte (or sporangies) after meiosis (reduction division), numerous haploid disputes are formed.

A dispute germinates in a plate (for example, Sfagnum) or a nitchautan (in the Kukushkin flax) proton.

The kidneys arising on the proton lend to new gamethophytes.

The department of mossoids is divided into three classes: 1) Antoncert, 2) hepatic moss, 3) leaf-weighting mosses.

Department of Playovoid

The Playovoid Department (Lycopodiophyta) is one of the most ancient groups of plants. At the end of the Paleozoic, gigantic tree-like plauinoids up to 30 m in height and up to 1 m in diameter - lepidodendrons, sigillaria, pleuromyia are numerous. Typical signs of ancient plauenia-shaped - dichotomous branching and cisoid leaves. Extinct tree-like plants formed stone coal deposits.

The plane-shaped department includes near modern 1000 species, 4 kinds, two classes: Plauanovye (representatives: a one-year plan, Balavovoid, Baranets, Selaginell Sibirskaya) and a half-feature (representative - a semi-half-hearth).

Modern plane-shaped - perennial herbaceous, usually evergreen plants with dichotomous branching of shoots, small sitting simple leaves and apparent roots.

Sporophylls (leaflets carrying sporangies) can be similar to conventional green leaves (born - huperzia) or differ from them and be collected in a sporing spikelet (genus plane - lycopodium).

There are pavement plants (class of shields, or half-hiking) and equinitioners (plane class)

The diploid generation (sporophyte) in the life cycle always dominates. The dispute is developing a gametophyte (outflow) - a perennial, having a view of a small tuber (2--5 mm in the diameter) with rhizoid formation. Gametophyte does not contain chlorophyll and feeds at the expense of endotrophic mycorrhiza.

Department Helds

The chests appeared in Devon, the separation of the department fell on the coal period. Happened from rhinofitis. Among the fossil representatives of the department are commonly tree forms, for example, Calamites

Currently, it is represented by one class horsetail (Equisetopsida) and only one genus - the Equisetum, which has about 30 species. All modern horsetails are perennial herbs. For the horsages, it is characterized by dismemberment of interstices and nodes with a mutton-located flavored leaves. Photosynthesis function runs. In xylem, the tracheids are common, there may be vessels; Floem - Synotoid tubes.

Long hypogogenic rhizomes are commonly, often with sparkling nodules. For sporing spikes, sporangophores are characterized on which spacengues are located.

Chests - Ravenbind plants. Gamenaophyte one- or OBEO. Gametophyte autotrophic, green.

Fertilization only in water drops.

Distribution: Various natural zones and plant communities are usually close to water. May be hard-painted weeds. Medicinal (can be used as diuretic).

Poisonous (destroys Vitamin B12 - Tiamine). Poisonous all kinds, all parts of the plants.

May cause diseases of herbivore animals (mechanical irritation of silicic acid mucosa and thiamine salts) - 40-80 days after grazing on the horsetail meadow in horses - aggressiveness, expansion of pupils, limb paralysis.

Department of Fern Summary

There were rhinofitis or similar plants. Today it is the most diverse and numerous group among higher vascular disputes, which combines about 10,000 species of plants of various appearance (terrestrial and aqueous herbaceous plants, tree shapes).

Modern ferns are found on all continents. It is known about 10,000 species (300 genera) of modern fern.

The wide range of environmental conditions has mastered - from deserts, marshes and rice fields, salted lakes to rainforest.

The maximum variety of species and life forms is characteristic of wet rainforest.

A variety of life forms of contemporary fern:

Tree-like up to 25 m high and 50 cm in diameter;

Small water ferns;

Terrestrial ferns with short epigeogenic rhizome;

Terrestrial ferns with a long hypogenic rhizome;

Epiphyts and Liana.

Ferns leaves (Wii) occurred as a result of the compaction of the large branches of their ancestors, therefore, shooting (macrophilles, body leaves). Usually Vaia Cherish.

Wii retain the Typical Growth Typical; In the young form of snippid twisted.

The stem from most ferns (except for tree) is not very developed.

Wii in some species combine the functions of photosynthesis and spioning (Orlyak, shield), others have two types of leaves: photosynthesis and sporing (ore).

Ground ferns - equalidation, aquatic - separation plants. Disputes are formed in numerous spouts, as a rule, on the underside of Wiji. Sports often form foods and are usually protected on top of the coat - the induction.

Some species have devices for active scattering argument (at the male shields, the excitement of ordinary and many other terrestrial ferns of the sporangies are revealed using a special mechanical ring consisting of cells with uneven thickened walls).

Little green gamemarketophytes are formed from the dispute. The division department is divided into 7 classes. Of these, 4 classes are represented solely by fossil forms. Modern ferns are represented by classes: Outflows (Uzhovniki), Maratty Polypodiopsyda.

Voted - evergreen, less frequently deciduous plants with a weathered stem, belonging to a tree or shrub, rarely - liana. Czech-shaped leaves, need-shaped, filament, different sizes. Reproduction and distribution occurs with the help of seeds ripening on the surface of seed scales. Characteristic is the presence of strobils (cones), pavement. Gametophyte is formed and develops in sporophyte tissues, strongly reduced. For female Gametophyte, the presence of Archeganiyev is characterized. After pollination, the male gametophyte forms a pollen tube, with which men's machines are delivered to the egg. The appearance of a pollen tube reduced the dependence on the water at the fertilization stage.

The viced department includes 6 classes, and the seed classes (Pteridospermae) and Bennettite ferns (bennettopsida) are completely extinct. Now the living gone, numbering about 700 species belong to the Cycadopsida classes (Gnetopsida), gingerbread (gnetopsida), ginkgy (GynkgoPsida) and conifer (Pinopsida).

Seed ferns resembled modern wood ferns, but multiplied by seeds, ripening directly on the leaves - megaphyllah. For Bennettite, richery gates resembling the structure of the flower of modern covered plants.

Class Sovagovye currently has about 120 species found in the tropics and subtropics. These are tree plants with large, hard, evergreen leaves, like resembling palm trees. Characteristic bombardness. Representative: Flooding Sugar.

The gift class includes representatives of three clans: ephedra (Ephedra), Welwitschia (WITWITSCHIA) and Gnetum (GNetum). Typical signs of oppressive - the presence of covers resembling a breakfast around the spores, branching gate assemblies, germs with two seedlines, the presence of real vessels, lack of resilne moves.

The ginkgov class includes one modern species - the relict plant of Ginkgo Two-Biloba (Ginkgo Biloba). This is a high leaf fall tree with two-sighted leaves. Characteristic bombardness, fireworks, seed with a lush shell, moving spermatozoa.

Class of coniferous, or pinsides, includes two subclasses: Cordate (Cordaitales) and conifer (Pinidae). Cordate - long-dimensional plants (large trees with firewall strobils).

Coniferous - the largest group of plants among the vicered, which ranks second after flowering plants on the role of the formation of vegetation cover.

Modern coniferous numbers about 560 species belonging to 55 genera and 7 families. Life forms of coniferous - trees and shrubs, as a rule, with evergreen, scratched or needed leaves. Root system, as a rule, rod. Branched minor roots perform the function of the formation of mycorrhiza. Representatives of pores. Pod civil - there are nodules with nitrogen fixing bacteria. Surveillance leaves or scratched (needles), less frequently broad-chain (gaming, araucaria). Most species leaves are evergreens, dense, leathery with pronounced xerorphic signs (Ustiani are immersed, there is a thick cuticle). Under the epidermis - 1-3 layers of the hypoderma.

Wood consists mainly of tracheid. Characteristic smolny moves.

One-bedroom plants, less often digestive. Gates separate-use:

Men's - microatruts (men's cones), consisting of their axes and microspophilles. The bottom is formed 2 or more microsposrans, in which pollen is formed. In pollen often developed air bags.

Women's - macrosticulas (cones), consisting of an axis, macrosphelmophilles (seed scales) and scales. On the upper side of the seed scales, 2 splaes are formed. Seed scales can be soft and brightly painted (teasel, subcourse, juniper) - apparently, imitation of flowering fruits.

Pollen has two shells - exine (external) and intin (inner). The shells diverge, forming air bags.

Seeds of different sizes and shapes. Many have wings to spread the wind. Juicy cover seeds of gumcarpuses, tees, etc. eaten by some animals.

The main features of the life cycle of conifers:

From pollination before fertilization is a year and more. Characteristic to pollination by the wind.

From fertilization until the seed ripening is a year and more.

Endosperm Gaploid - reduced female Gametophyte.

A pollen tube is formed, growing from the micropower to the egg.

The seed consists of seed peel (blasting of the semester, 2N), the embryo of a new sporophyte (2N), endosperma (N) (see .Ris.).

In modern flora, representatives of the orders of araucaria, sub-circuit, pine (spruce, fir, pine, larch), cypress (sequiladron, sequoia, swamp cypress, cypress, juniper) and teasing (teasing berry) are common.

Department Covered Plants

The development of coated-brimmed plants was a new stage in the evolution of the plant world. This is the youngest of all departments, characterized by a large variety of species and widespread. More than half of the species growing on the globe belongs to coated plants. The following features in structure and development are characteristic of the coated brine:

the emergence of a new organ - a pestle, under the protection of which seeds develop inside the ovary;

in the ripening of seeds from the zeroze, the fruit that protects the seed from external influences is formed, hence the name - coated;

further simplification of sexual generation led to the almost total reduction of the female inapproachment, the male stroke is represented by two cells;

a new process of double fertilization leads to formation simultaneously with the germ of the secondary endosperma.

the emergence of the perianth provided the best protection of pollen in the stamens and seeds in the wounded and promoted the development of pollination by insects.

The complication in the structure of the wood led to the formation of new conductive elements - vessels.

The large variability of the vegetative organs contributed to the emergence of a large formal diversity of them and the settlement of spaces with various conditions of habitat - from the desert to the aquatic environment.

The development cycle of coated bridges is as follows.

A plant with roots, stems, leaves, on which flowers are formed at a time during flowering, grow out of the seed embryo. The most essential parts of the flower - stamens and pestles. The perianth (cups and petals) protects them from drying out, from excess moisture during the rain and. Dew and attracts insect pollinators.

In the anthers of the stamens there is a fabric of the Archeuria, the cells of which are reduced reductionally carookinetically, and four haploid cells of pollen are formed from each maternal arcorption.

Their further development occurs on the surface of the stroke, where pollen shares, and two cores are formed, one remains the core of a large, so-called vegetative cell pollen, the second becomes the core of a small naked anteridal cell immersed in the cytoplasm of a large cell. The pollen germinates, and the cytoplasm of the vegetative cell, together with the core, flows into the pollen tube, becoming an anteridal cell, which is divided and forms two elongated immobile sperm (men's gemnets).

The seedwork consists of a multicellular tissue of a nicklice, covered with two seals forming the dust. One of the cells of the nomalus grows, it is divided by reduction, then the carokinetically and forms four haploid cells, of which three die, the fourth increases in size and turns into an embryonic bag. As a result of the three-time division of its nucleus, eight nuclei is formed, the cytoplasm is isolated around six of them and naked cells occur, two cores converge in the center, merge and turn into a diploid secondary germ bag. Three haploid cells are located in a germ bag closer to the dust, form an egg apparatus consisting of two cell-satellite cells - synergide and one, larger egg. In the opposite part of the embryo bag, three haploid bare cells are placed - antipodes.

If the contents of the pollen tube are typical for coated double fertilization, the contents of the pollen tube fall into the embryonic bag and the first sperm merges with the egg, forming the zygot (diploid), which develops into the germin. The second sperm merges with the secondary germ kernel (diploid) and a new triploid core is formed. After dividing this nucleus with a triple set of chromosomes, a fate of a secondary endosperma with a nutrient reserve is formed. During the formation of the embryo, the seedhead turns into a seed, marking - in the fruit.

In the development cycle of coated bridges, the alternation of two generations is also occurs: sexual and crucible. The pollen, which is formed, as well as in the vicered, after the reduction division of the cells of the arcussion in the anthers, corresponds to the microsporement (the haploid cell), and the development of male sexual generation begins with it.

Male Gametofit consists of two cells: a vegetative cell - a primitive male overgrowth, and an anteridal cell, which is anteridiment. Sperm - Gamets correspond to spermatozoa, but differ by immobility.

The development of female sexed generation begins with a reduction division of one of the cells of the nomalus and the formation of a gaploid cell - creeper bag, which is the macrospheres of the coated bridge. In the macrosphere, the germ bag is a magnitude of everything from three antipod cells, and the egg apparatus is the remains of Archegononia, from which the coated bridges remained only two cells - synergies and eggs (goveta). When merging with sperm with an egg, the development of sexual generation (Gametophyte) ends with the formation of zygotes (diploid cell), the development of a new, most of the useless generation - sporeophyte, initially embryo, then all the plants, all the organs of which are diploid cells. In anthers and seeds of flowers after a reduction division begins the development of sexual generation.

Most of the systems are divided by the department of coated in two classes: dicotyled and monocotted. The class of dwoom colors includes plants from which the embryo has two semilaries, the leaves with a cigarette housing, the primary structure of the stem is characterized by open vascular fibrous beams, located circles, rod root, four-five-five flower.

The class of monocoons includes plants in which the germ has one seedliness, the leaves with don-thought or parallel-solid housing, the stem in the primary structure contains closed vascular fibrous beams, the root of the urine, three-meted flowers. The most ancient are boring plants, from the primitive forms of which one-bedroom branch was once separated, which reached in their evolution at least complex shapesthan dicatoral.

Thus, the coented dominant is an affordable generation, and sexual develops on mileage. Secondary endosperm, whose cells have a kernel with a triple set of chromosomes, can not be attributed to a sporeophyte, nor to the gamemarket. This peculiar fabric is only peculiar to the coated bridge.

Conclusion

seed bobby spore plant

When comparing the cycles of the development of higher disputes and seed plants, it is clear that the continuous change of generations is peculiar to all of them: sexual generation - sexually generation - sexual. These generations differ in the complexity of the structure, sizes, formation on the sexual generation Games, on the fabric - dispute and by the number of chromosomes in the nuclei of their cells (haploid or diploid nuclei). The transition of one generation to another is carried out by two processes: the merge of the weights leading to the formation of a diploid cell - zygotes, and a reduction core division leading to the formation of haploid disputes. These processes determine the borders of generations and lead to the appearance in the first case of the diploid cull, in the second haploid sexual generation.

The alternation of generations is well pronounced in all departments of plants, but the domination and degree of development of these generations in different departments are different, which is largely due to the conditions of their lives. The moss dominant is the sexual generation, the plant itself, the genitals with gamets develop on it. The process of fertilization occurs only in the presence of water, so the MAs are usually growing in raw materials and do not reach large sizes. Periodically, their thickets are saturated with water, according to which sperm and moves to the eggs. Miscellaneous generation moss, leg and box are developing on sexual generation.

The vicious generation is dominated by the digestive generation (tree itself), it achieves great difficulty and significant sizes. All the development of microscopic female sexual generation occurs on the bunch of generation under the protection of the seedness, and the wind pollination ensures the transfer of pollen and the possibility of fertilization. The formation of seeds and pollination by the wind contributed to the resettlement of gone to more diverse conditions of habitat.

The covered brine also dominates the useful generation with a greater complexity and a variety of structure (plant itself). Microscopic female sexual generation is fully developed on a bunch of generation under the protection of the pestle. Pollination by the wind and insects even more reliably ensures the transfer of pollen, and consequently, the fertilization of the egg. The diversity in the structure of vegetative organs, the formation of seeds and fruits contributed to the resettlement of covered with the most different habitats. The rapid development of coated plants has changed the appearance of the vegetation of the globe. Monotonous and monotonous thickets of ferno-shaped and viced were replaced by vegetation bright and diverse in the color of foliage, flowers and fruits from representatives of coated bridges.

Currently, the coated bridges occupy a dominant position in the vegetation of sushi. They ensured the development of the animal world, especially mammals and birds, as they serve as a feed base. Simultaneously with the development of coated plants, some insect groups developed, which led to a large mutual fitness of flowers and insect pollinators.

The exceptional value of the coated plants have in human life, providing it with food and materials of plant origin. As further comprehensive study, their meaning will increase.

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Plant development cycles Preparing for the implementation of the tasks of the EGE C5 (the use of knowledge on the definition of the number of chromosomes and DNA in different phases of mitosis and meiosis, in the genital and somatic cells of different organisms) © Tikhonova E.N. January 6, 2015

As shown by the results of the past years: students have poorly formed knowledge about changing chromosomal set in the cells of the gamemarketophyte and sporophyte of algae, moss, ferns, gym and flowering plants; on formation in plants a dispute in the process of meiosis, and sex cells - in the process of mitosis, which distinguishes them from animals; ability to compare disputes and sex cells, disputes and cells of sporophyte; Explain and argue the features of the formation of dispute, genital cells, Gametophyte in plants.

Life stages of plants Spiritophyte Gamenaophyte literally carrying disputes All cells contain a diploid set of chromosomes (2N) forms disputes (N) literally carrying grounds All cells contain a haploid set of chromosomes (N) forms Gamets (N)

Dictionary (Reimers N.F.) Sporophyte Representative of the Miscellaneous Generation or Stage of the Life Cycle Plants from Zigota Before Education Spore Gametofit A representative of the sexual generation or a stage of the life cycle of plants from disputes before the formation of zygotes

Dictionary (Reimers N.F.) SPOORGIA Agenial reproduction of plants and mushrooms, in which the disputes of gamentangi sex organs formed, mushrooms, in which GaMames are formed

Generations The sexual sexual 2n develops from the zygota sporephite controversy (N) (Meiosis) n develops from disputes Gametofit Gameta (N) (mitosis)

Disputes (N) - Why then these are culls, and Gamets (N) - sex?! Let's figure out! The haploid dispute (one) is not merging with any other cell forms a new organism (or rather other life stages) genetically identical to this one dispute T.O. The dispute, being a product of the sporophyte itself forms the future Gametophyte ═\u003e The reproduction of the crucible tissue of the gametophyte haploids of them is formed by the gametes each haploid goveta does not forms a new organism. Only after the step of fertilization of it with another games (after combining the genetic material (N) ♀ and (n), the Games is formed, diploid (2 n) zygote). So Gamets, being a product of the haploid gametophyte, only merging into the pairs of men with women will ensure the further development of the new organism ═\u003e Genuine

Casual generation sexual generation Meiosis spores N n n 2n mitosis x zyagota 2n ♂ ♀ N n n mitosis

Sporophytes Gamenaophyt

Cycle of Development of Listed Moss (Cukushkin Len)

Exercise 1 . "The division of mossoid" in the life cycle of mossoids prevails (_). Moch-like breeding (_). Miscellaneous reproduction occurs with (_). Disputes, as well as all higher plants, are formed (_), and have (_) a set of chromosomes. Sporophyte Mukhov (_). Gamenaophyte MPA presented (_). Gametophytes are called dwarm, if (_). Aniardia and Archegononia at the moss are formed on (_). For the fusion of germ cells is necessary (_). After fertilization from the zygota develops (_). From disputes of MCH develops (_). When Meiosis occurs in the Moss Development Cycle (_)

Task 2. "Department of Fern Sports" Sporophyte of ferns is presented (_), Gametofit - (_). Strobils in ferns (_). Aniardia and Arhegononia at the male panel are formed on (_). The disputes at the male panel are formed on the bottom of the sheet in (_), covered with a bedspread - (_). What is the most powerful generation in ferns? Reply explain the answer. What is the floor generation in ferns? Reply explain the answer. Where are the gametes for the fern? How is the sexual reproduction in fern? Where are the disputes for fern? How is the most powerful reproduction in fern? Where is the germ forms a new plant in fern?

Pine Development Cycle

Task 3. "Division of vote" What is the spore-sprochers? What is the presented male gametophyte vote? What is the female gametophyte vote? The main aromorphoses, which led to the appearance of voted? What are the presented microsporegia voted? What are the megaloprangies of vote? What are the gamentangia vote from themselves? When is Meiosis in the life cycle of gifts? What is developing from microspore and megapar vote?

Task 4. "Department of Vote" What features is Pine Pollen? What is the presented male gamemetophyte forming sex cells? What is presented for a female gamethophyte forming sex cells? Does water need for fertilization of vote? Why? Where is the germ forms a new plant at pine?

Task 7. "Department of vote" in the spring of the pine on each sca of reddish cones is formed by .... Megasporangiy gifts are presented .... In Nomeglus, the Megosocyt undergoes Meiosis, three megasy die away, and the core of the fourth .... On the scales of greenish-yellow cones, formed at the base of young shoots, are formed .... Microspocytes meotically share and form ..., each of which forms as a result of mitotic divisions .... In pollen grains there are several cells: .... Fertilization at pine originarity ... after pollination. One of the sperms merges with an egg, and the second .... The second Archegonia of the female Gametophyte is also .... The ripening of seeds at pine is only through ... after pollination. From the fertilized egg, the zygotes, forms .... Endosperm in the vicered .... For fertilization of gifted water .... Unlike the dispute, the seed of pines has ....

Megaspora (N) Female Gametofit (germ bag) (N) Microspore (N) Male Gametofit (pollen grain) (N)

Sex generation N Mitosis Gamet n fertilization of zygota 2 n Casual generation 2 n Meiosis spores n

Task 5. "Division of the coated bright" What is the spores of the flowering? What is the male gametophyte of flowering? What is the Women's Gametophyte Flower? The main aromorphoses that led to the appearance of flowering? What are the presented microsporegies of flowers? What are the megaloprangies of flowers? What is the gamentangia of flowers? When in the life cycle of flowers occurs meyosis - when forming a gamemet or dispute? What is developing from microspores and megapar flower?

What is indicated in the figure figures 1 - 6? When is Meiosis occurs - when the dispute is formed, or when it is admitted?

Task 6. "Double fertilization of flowering plants" Male Gametofit of flowering plants is presented (_). Pollen grain on the barn of the column swells and forms (_). The generative cell is divided and forms (_). Sumpers are protected (_), between which there is a hole - (_). Female Gametophyte of flowering plants is presented (_). Inside the seed is developing (_), consisting of seven cells. One sperm merges with (_), the second - (_), that is, two fertilization occur. Double fertilization was open to Russian scientists (_). The germ of the seed develops from (_). Endosperm is formed from (_). Perisperm is formed from (_). The peel of the seed is formed from (_) the ocoplodnik is formed from (_).

Chromosomal set of wheat somatic cells is equal to 28. Determine the chromosomal set and the number of DNA molecules in the cells of the family before the start of MEIOS, at the end of the MEIOSA 1 object and the MEIOS telfase 2. Explain which processes occur during these periods and how they affect the changes in the number of DNA and chromosomes. . 1) Before the start of MEIOS, the chromosomal set in the cells of the double (2 n) -28 chrose, in the interfax, the DNA molecules occurs, therefore the number of DNA molecules of molecules (4C). 2) In the first division of MEIOS, homologous chromosomes consisting of two chromatids are diverged, therefore at the end of the MEIOSE elekase 1 chromosomal set in cells single (N) - from 14 chromosomes, the number of DNA molecules (28 DNA molecules). 3) In the second division of meiosis, chromatids diverge, therefore, at the end of the BELFAZ 2 MEIOSE chromosomal set in cells single (N) -14 chromosome, the number of DNA molecules is 14 molecules (1C).

The chromosomal set of somatic wheat cells is equal to 28. Determine the chromosomal kit and the number of DNA molecules in one of the cells of the family before the start of MEIOS, in the anatherapy Meiosis I and Anafase Meiosis II. Explain which processes occur during these periods and how they affect the change in the number of DNA and chromosomes. 1) Before the start of Maizo, the number of DNA molecules - 56, as they double, and the number of chromosomes does not change - they are 28; 2) in the Anafase of Maiza I, the number of DNA molecules 56, the number of chromosomes - 28, homologous chromosomes are diverged into the cell poles; 3) In Anafase Meiosis II, the number of chromosomes - 28, nursing chromatides diverge to the poles of the cells and become independent chromosomes (but they are all in the same cell), the number of DNA molecules - 28, after the first division of DNA doubling does not occur, therefore the number of DNA has decreased in 2 times.

In the cells of the endosperm seeds of lily 21 chromosome. How will the number of chromosomes and DNA molecules at the end of the Maizo 1 and Maizo MEIOS 2 compared to the interfaz of this body? Reply explain the answer. 1) Endosperm of flowering plants has a tripotoid set of chromosomes (3 N), which means that the number of chromosomes in a single set (N) is 7 chromosomes. Before the start of MEIOS, the chromosomal set in the cells of the double (2 n) of 14 chromosomes, in the interfax, the DNA molecules occurs, therefore the number of DNA molecules (4C) occurs. 2) In the first division of MEIOS, homologous chromosomes consisting of two chromatids are diverged, therefore at the end of the MEIOS's elephant 1. Chromosomal set in cells single (N) of 7 chromosomes, the number of DNA molecules (2c). 3) In the second division of meiosis, chromatids diverge, therefore at the end of the telfase 2 MEIOSE chromosomal set in cells single (N) -7 chromosomes, the number of DNA molecules is one-7 (1c).

What chromosomal set is characteristic of the nucleus and endosperm seed cells, leaves flower Plant. Explain the result in each case. 1) In the cells of the seed embryo, the diploid set of chromosomes - 2N, since the germ develops from the zygote - a fertilized egg; 2) in the endosperm cells of the seed tripotoid set of chromosomes - 3N, as it is formed when the two central cell nuclei is formed (2N) and one sperm (N); 3) Cells of the flowering plant leaves have a diploid set of chromosomes - 2n, as an adult plant develops from the embryo.

What chromosomal set is characteristic of pollen grain and sperm cells? Explain from what source cells and as a result of which division is formed by these cells. 1) Cells of pollen grain pine and sperm have a hollow-shaped chromosome set. 2) Cells of pollen grain pine are developing from haploid dispute by mitosis. 3) Pine sperm develops from pollen grain cells (generative cells) mitosis.

What chromosomal set is characteristic of sperm and cells of the endosperm of the seed of a flowering plant? Explain from which cells and as a result of which division these cells are formed. 1) in sperms a set of chromosomes of haploid, the cells of the endosperm of the seed - triteoid. 2) Sperm will be formed from the haploid dispute (male gametophyte generative cell) as a result of mitosis. 3) endosperm is formed by the merger of two haploid nuclei of the central cell of the embryonic bag (2 n) and one sperm (N).

What chromosomal set is characteristic of epidermis cells and an eight-year germ bag of a silver flower plant? Explain from what source cells and as a result of which division is formed by these cells. 1) List part of the sporophyte of the flowering cell of the cells of which diploid (2N). The eight-cherished germ bag is the immature female Gametophyte of the flowering plant of the cells of which haploid (n) 2) of the sheet cells are formed in the mitotic division of the educational tissue (including the cells of the leaf epidermis). 3) The cells of the eight-cherry germ bag are formed in the mitotic division of megapar from which the female Gametophyte of the flowering plant is formed.

What chromosomal set is characteristic of hamet and dispute plants moss cucushina flax? Explain from which cells and as a result of what division they are formed. Gameta moss Kukushkina flax is formed in Gametophytes from the haploid cell by mitosa. 2) A set of chromosomes in Games single - n. 3) Spores of the MCH Cukushkina flax are formed in the diploid sporophyte in the spouts by meiosis from diploid cells. A set of chromosomes in a dispute is single - n

What chromosomal set is characteristic of Gamenaophyte and Games Moss Safagnum? Explain from what source cells and as a result of which division is these cells formed? 1) GaMetophyte and sphagnum gamets haploid, and a chromosome set, and the amount of DNA in cells correspond to the NC formula. 2) Gamenaophyte is formed from a dispute, which is formed as a result of Maiza from sporophyte tissues. 3) The dispute is divided by mitosis, forming a Gametophyte.

The haploid set of pea chromosomes is 7. How many chromosomes are contained in leaves cells, seed embryo and seed seeds. Reply explain the answer. one. Sheet-vegetative The organ plant, the cells contain 2n chromosomes, therefore, they contain 14 chromosomes 2. The germs of the seed is formed as a result of fertilization, therefore, in them the diplotoid set of chromosomes (2n \u003d 14) 3. Semi-sodts of pea seed contain spare nutrient, they are formed as a result of merge sperm (N) and central cells of the nexian (2N) and has a triple chromosome set (3 n \u003d 21)

It may be simple and difficult. As an example of a simple cycle, it is possible to bring Chlorella, which breeds disputes. Developing this green algae becomes equipping 4-8 autosports, which grow inside the maternal organism and are covered with their own shell. But among the plants, a complex development cycle is more often found, which consists of 2-3 ordinary.

Features of the life cycles of plants

An important property of all living is the ability to multiply. The method of reproduction happens:

sexual (govetas);
crucible (disputes);
vegetative (part of the body).

In complex cycles, there are always several separate phases of gamets and zygotes during sexual reproduction. Gameta is a ripe genital cell with a haploid (ordinary) set of chromosomes. The zygote with the diploid (double) set is formed as a result of the combination of two heats. From the zygota, sporeophyte develops, which produces haploid disputes. From the dispute - Gametophyte, which is male and female.

For example, it is possible to take the equaliforous fern, who has two forms of individuals - the fern itself (sporophyte) and its overgrown (Gametofit). The outflow is the offspring of adults of fern. It exists a very short period, but he has time to produce a single large-scale individual. The life cycle of plantism is this feature of the reproduction consists of alternating generations: from an adult ferns to a reproduction and again to adult fern.

Methods of breeding

Most plants breed in gender. At the same time, the formation of a new organism from the zygota after fertilization and the association of Games (Singhamia). Parthenogenesis - reproduction without fertilization - also refers to the sexual way: a subsidiary is formed from the isochuets that the sizes and disputes relatives. Sexual reproduction is almost always combined with other methods - vegetative or punched, since it is characterized by low productivity.

At the same time, this method and the most powerful reproduction occurs in ferns, and in a bundle with a vegetative option - in some algae. In seed plants, the formation of a genital cell occurs from one subsidiary zygote, as a result of which this process is no longer reproduced, but reproduction.

In the mileage of reproduction, zyospores are formed - cells without a cell wall, which in multicellular plants are in special spouts, and fixed cells - aplanery. Alone, this method of reproduction is found in nature very rarely. It is usually combined with sex or vegetative.

There are 2 types of dispute: Mitospoda, which occur in the displacement of the method of reproduction, and meiospore - arising during sex. Mitospores appear with mitosis, resulting in a person, similar to maternal. MEYOSPORIA is formed by means of meiosis during the germination of the zygote or in the spouts. For most plants, both breeding methods are characterized, due to which two different forms of individuals are obtained.

Vegetative breeding method

With a vegetative variant of reproduction, the acintetes are separated - thick-walled cells. It lies in the separation from the motherboard of some kind of part of its part - broken kidney or taurus. In this way, some, including Sargassive, brisk and vegetatively, even flowering plants are breed and vegetatively multiplied with vegetatively. Some of them produce brood kidneys, which fall on the ground and are rooted there. Also, the kidneys can be branched and separated from the parent plant. The coated brimmer group of plants is very often the development of shoots under the ground from the rhizoma.

Plant Spreads

One of the final reproduction stages is the spread of plants. In nature, there may be 3 options for resettlement: germs, disputes and seeds. In extremely rare cases, distribution can occur with the help of the zygota. Even K. Linney tied the seed and dispute dissemination with the creeping and pivotilic plants. The second type includes a group of vote and coated plants, and to the first - all other groups, including algae, moss and ferns.

Plant breeding methods have passed a long evolutionary path from vegetative to crucible and sex. Now the separation of plants for dispute and seeds is not associated with propagation, but with reproduction. The seed method is allocated in a separate group, as it is considered to be a compound of reproduction by disputes and gates. Semyon reproduction includes several stages: the formation of the zygot, heams, dispute, germs and seeds, as well as the resettlement of the plant.

Alternation of generations

The life of plants in the form of two different generations can wear different names: change forms of development, alternation of generations, etc. Consumption of a large fern and the ingrowth in the case of an equaliforous ferner - this is an example of generation alternation marked by the adult phases of the forms of individuals. These two forms are so different outwardly that they are difficult to find out the same plant. The stroke of the fern is very difficult to notice with a naked eye. At coated plants an analogue of the outflow is an embryonic bag, which is extremely small and hidden in the depths of the flower. Among some groups of algae, these forms of individuals are similar appearance, but completely vary in biological signs. The alternation of generations is found almost all higher plants and evolutionary developed algae.

Life cycles of higher plants

The life cycle of higher plants, except for mugh-like, is characterized by the fact that the Gametophytic is poorly developed, and the sporeophyte is mostly occupied in the life cycle. They differ in that the sporophyte develops inside the female genital organ and is in continuous communication with the gametophyte. In the case of it looks like a box with disputes growing from the top of the gametophyte.

The remaining higher plants have pronounced spores, which are large and complex with such bodies as foliage, stems and root system. Most plants that a person imagines themselves when speaks of horses, ferns or other groups, - sporophytes.

Life cycles of flowering plants

The most progressive in terms of evolution are flowering plants. The life cycle of flowering plants is characterized by the fact that often the embryo is able to develop from a non-advocked egg (apomixis). The predominant form of flowers is a pavement sporophyte, which is a plant with leaves and stem. Male Gametofit is represented by pollen grain, and a female - a germ bag (it develops faster than that of vote). The organ of both sexual and powerful reproduction is a modified escape - flower. The seeds are protected by the walls of the marks. The life cycle of the development of plants of this group ends after fertilization and formation of seed, the germ in which has a supply of nutrients and does not depend on external factors.

Life cycles of vote and coated plants

To group gamed plants Representatives of coniferous trees and shrubs. Most of them have modified needle leaves. The life cycle of gone plants is characterized by the fact that the microspores (pollen) are formed in small men's cones (anthers), and megasy - in female (segatives). Male Gametofit is formed from the microspid, and from Megasport - female. The life cycle of the plant from this group is characterized by the fact that fertilization occurs with the wind, which delivers pollen to the segments. After that, the germ begins inside the seedwork, and the seed is formed from it. It lies on seed scales and is not covered. The seed gives a new sporophyte from which a new plant grows.

Plants are characterized in that this group has a flower in which disputes are formed and fertilizing the gametophytes and the development of seeds. The peculiarity of this group is to protect seeds that are hidden inside the fetus and are protected from exposure to the external environment.

Life cycle of disputes of plants

Spore plants do not bloom, therefore they are also called non-flowered. They are two categories:

higher (ferns, chests, mosses, planes);
lower (algae, lichens).

The life cycles of dispute plants depending on the species can go a sex or sexual option. They are not able to multiply in gender without the participation of the aquatic environment. For sexual reproduction, Gametophyte is used, and for the cullless - sporophyte. There are two subgroups of dispute plants: a haploid and diploid. The haploid subgroup includes mosses, horships and ferns, which are more developed by Gametophyte, and the sporophyte is formed in the form of a contrary. The haploid subgroup is characterized by the fact that the sporophyte has a subordinate status in it.

Plant Life Cycles: Schemes

Mossi - representatives of the primitive type of higher plants. They have a very conditional division of the body on the stem and leaves, instead of roots - thread-shaped rhizoids. They grow in swampy, wet places and evaporate moisture very much. We multiply the sexual way, the sporophyte depends on the Gametophyte, the disputes are formed in a special box, which is above the Gametophyt and is associated with it.

Representatives of ferns have large pasty leaves (sporangies are located on the underside). The plant has a pronounced root system, and the sheet is actually a system of branches, which is called Waiy or an extraordinary. The life cycle of fern consists of two phases: sexual and cruel.

The field phase occurs with the participation of Games, and the disgrace - the dispute. The most powerful generation begins with diploid zygota, and sexual - with haploid dispute. The changeability of these phases is most of the cycle.

Solving the task of the EGE on the life cycle of plants
The concept of the life cycle of plants
In the life cycle of plants there is an alternation of cullless and sexual reproduction and associated alternating generations.
Haploid (N) vegetable organism forming gemnets is called Gametofit (N). It represents the sexual generation. Gamets are formed in the genitals by mitosis: spermatozoa (N) - in Anteridias (N), egg cells (N) - in Archegonias (N).
Gametophytes are routine (on it developing and surias and archegononia) and separation (Andesteria and Archegonia are developing on different plants).
After the merger of Games (N), the zygota with a diploid set of chromosomes (2N) is formed, and it develops with mitosis with mitosis - sporophyte (2N). In special organs - sporangies (2N) of sporophyte (2N) after meiosis, haploid disputes (N) are formed, in the division of which new gamemarketophytes (N) are developing mitosis.
Life cycle of green algae
In the life cycle of green algae, Gamenaophyte (N) prevails, that is, the cells of their layers of haploid (N). At the occurrence unfavorable conditions (Cooling, the drying of the reservoir) takes place in sexual reproduction - the gearboxes (N) are formed, which are pampered in the zygot (2N). The zygote (2N), covered with a shell winter, after which, with the occurrence of favorable conditions, it is divided by meyosis to form a haploid dispute (N), of which new individuals (N) are developing.
Task 1. What kind of chromosoma set is characteristic of a climbing of the Ulotriks and for Himself? Explain from which source cells and as a result, what division they are formed.
Answer:
1. In the cells of the hollow-shaped set of chromosomes (N), they develop from disputes with a haploid set of chromosomes (N) by mitosis.
2. In the govetakes, the Hapo-shaped set of chromosomes (N), they are formed from the cells of the layer with a haploid set of chromosomes (N) by mitosis.
Task 2. What kind of chromosoma is characteristic of the zygota and for the argument of green algae? Explain from what source cells and how they are formed.
Answer:
1. In the zygote, the diploid set of chromosomes (2N), it is formed when the heams with a haploid set of chromosomes (N).
2. In the disputes of the haploid set of chromosomes (N), they are formed from zygotes with a diploid set of chromosomes (2N) by Maiza.

Life cycle Mukhov (Cukushkin Len)
Makhov in the development cycle prevails a sexual generation (N). Flameable plants moss - separation of Gametophytes (N). Alterias (N) with spermatozoa (N) are formed on men's plants (N), on female (N) - archegononia (N) with egg cells (N). Using water (during the rain), spermatozoa (N) falls to egg cells (N), fertilization occurs, zygote (2N) occurs. The zygote is located on the Women's Gametophyte (N), it is divided by mitosis and sporephite develops (2N) - a box on the leg. Thus, sporophyte (2N) in Mukhov lives at the expense of the female gamethophyte (N).
In the sporophyte box (2N), the dispute (N) is formed by meiosis. Mossi - Drafting plants, distinguish the microspores - men's and macrospheres - female. From the dispute (n) by mitosis, the ranks first develop, and then adult plants (N).
Task 3. What chromosomal set is characteristic of hamet and argument of the crunch of flax? Explain from which source cells and as a result, what division they are formed.
Answer:
1. In the govetakes of MCH CUKUSHUS Flax, the Gaploid set of chromosomes (N), they are formed from Anteridiev (N) and Archeganiyev (N) of male and female gametophytes with a haploid set of chromosomes (N) by mitosis.
2. In disputes of the haploid set of chromosomes (N), they are formed from sporophyte cells - boxes on a leg with a diploid set of chromosomes (2N) by Maiza.
Task 4. What chromosomal set is characteristic of the cells of the leaves and the boxes on the leg of the crunch of flax? Explain from which source cells and as a result, what division they are formed.
Answer:
1. In the leaf cells of the leaf of the flax, the Gaploid set of chromosomes (N), they, like the whole plant, are developing from the dispute with the haploid set of chromosomes (N) by mitosis.
2. In the cells of the box on the leg, the diploid set of chromosomes (2N), it develops from the zygota with a diploid set of chromosomes (2N) by mitosis.
Lecture
Life cycle of fern
Ferns (also horsetails, plauines) in the life cycle, sporeophyte prevails (2N). On the lower side of the leaves of the plant (2N), sporangies (2N) develop, in which disputes (N) are formed by meiosis. From the controversy (N), which fell into the wet soil, germinates (N) - Ozoeple Gametofit. Alterias (N) and Arhegonia (N) are developing on its lower side (N), and spermatozoa (N) and egg (N) are formed in them by mitosis. With drops of dew or rainwater, sperm (N) fall to egg cells (N), the zygota (2N) is formed, and from it - the germ of the new plant (2N). (Slide demonstration).
Scheme 3. Life cycle of fern
Workshop
Task 5. What chromosomal set is characteristic of the leaves (wai) and the fermentation in the ink? Explain from what source cells and as a result of which division is formed by these cells.
Answer:
1. In the cells of the fern leaves, the diploid set of chromosomes (2N), so they, like the whole plant, are developing from zygotes with a diploid set of chromosomes (2N) by mitosis.
2. In the cells of the otro-shaped set of chromosomes (N), since the outflow is formed from the haploid dispute (N) by mitosis.
Lecture
Life cycle of gone plants (pine)
The leafy plant of gifted plants is sporing (2N), which develops women's and men's cones (2N).
On the scales of female cones are located in the megaloprangia (2n), in which 4 megasives (N) are formed by meiosis, 3 of them die, and from the remaining - the feminine Gamesophyte - endosperm (N) with two archeganis (N) develops. In Archeganos, 2 egg cells (N) are formed, one dies.
In the scales of men's cones, pollen bags - microsposrangia (2N) are located, in which microspores (N) are formed by meiosis, male gametophytes are developing - pollen grade (N), consisting of two haploid cells (vegetative and generative) and two aircases.
Pollen grains (N) (pollen) wind are transferred to women's cones, where 2 sperm (N) is formed by mitosis (N), and from a vegetative (N) - a pollen tube (N), which is driving inside the sperm and delivering sperm (N ) To the egg (N). One sperm dies, and the second participates in fertilization, the zygota (2N) is formed, from which the germ of the plant (2N) is formed by mitosis.
As a result, a seed coated and containing inside the embryo (2N) and endosperm (N) is formed from the selection.
Scheme 4. Life cycle of gone plants (pine)
Workshop
Task 6. What chromosomal set is characteristic of pollen grain cells and pine sperm? Explain from what source cells and as a result of which division is formed by these cells.
Answer:
1. In the cells of the pollen grain, the chromosomes (N) set (N) set, as it is formed from the haploid microspor (n) by mitosis.
2. In the sperms of the haplopoid set of chromosomes (N), as they are formed from the generative cell of the pollen grain with a haploid set of chromosomes (N) by mitosis.
Task 7. What chromosomal set is characteristic of megas and endosperm pine cells? Explain from what source cells and as a result of which division is formed by these cells.
Answer:
1. In Megasporah, the Hapo-shaped set of chromosomes (N), as they are formed from the cells of the Self (Megasprangia) with the diploid set of chromosomes (2N) by Maiza.
2. In the endosperm cells, the chromosomes (N) set, since the endosperm is formed from the haploid megacpus (N) by mitosis.
Life cycle of coated plants
Covenate plants are spores (2N). The organ of their sexual reproduction is a flower.
In the margin of the flower pestles are the megaloprangies (2N), where Meiosis occurs and 4 megasives are formed (N), 3 of them die, and from the remaining - the female GaMetophyte is developing - an embryonic bag of 8 cells (N), one of them - egg cell (n), and two merge into one - a large (central) cell with a diploid set of chromosomes (2N).
In microspores (2N), microspores (N) are formed by MEIOS's antips (N), from which men's gametophytes are developing - pollen graft (N) consisting of two haploid cells (vegetative and generative).
After pollination from the generative cell (N), 2 sperms (N) are formed, and from the vegetative (N) - the pollen tube (N), which is rotating inside the dormitory and delivering sperm (N) to the egg (N) and the central cell (2N). One sperm (N) merges with the egg (N) and the zygota (2N) is formed, from which the mitosis is formed by the germs of the plant (2N). The second sperm (N) is merged with a central cell (2N) to form a triploid endosperma (3N). Such fertilization of coated plants is called double.
As a result, a seed coated and containing inside the embryo (2N) and endosperm (3N) is formed from the selection.
Scheme 5. Life cycle of coated plants
Task 8. What chromosomal set is characteristic of the microspiona, which is formed in the flesh, and the cells of the endosperm of the flower plant seed? Explain from what source cells and how they are formed.
Answer:
1. In the microspores, the Hapo-shaped set of chromosomes (N), as they are formed from microspoorangiyev cells with a diploid set of chromosomes (2N) by Maizo.
2. In the endosperm cells, a trite-shaped set of chromosomes (3N), since the endosperm is formed by the merge of the haploid sperm (N) with the diploid central cell (2N).
General conclusions
1. In the process of the evolution of plants there was a gradual reduction of the gamemarketophyte and the development of sporophyte.
2. In the govetakes of plants, the garoid set (n) chromosomes, they are formed by mitosis.
3. In the buildings of plants, the haploid set (n) of chromosomes, they are formed by meiosis.

The role of sexual reproduction in wildlife.

With sexual reproduction, new combinations of genes are constantly being created, which increases the genetic diversity of offspring and, accordingly, the chances of adapter to changing environmental conditions. Creating new combinations of genes occurs in the process mEIOSA. Meiosis takes place during the formation of haploid cells (dispute or heights) from diploid cells. At the same time, the chromosomes that have been given by the body from mother and father cease to exist as a whole - as a result of the crossing agener, new versions of chromosomes combined from paternal and maternal are formed. Thus, chromosome children are usually not identical to the chromosomes of parents - they contain other combinations of alleles (gene options).

During MEIOS, the reduction of chromosomal set occurs - education from the diploid cell 4 of haploid cells (N), in which each chromosome is no longer a pair of nursing chromatids, but 1 chromatide. In humans, sex cells are formed by meiosis, each of them carries 23 chromosomes.

The diploidity of cells in the life cycle is restored at fertilization - the merge of the weight. At the same time, two different chromosomal sets of two different genomes (the genome of the mother and genome of the father) are combined.

Types of life cycles.

Various organisms demonstrate a large variety of life cycles, but in all types of life cycles you can allocate diploid phase, or diplophase (from fertilization to meiosis) and gaplooid phase, or gaplophase (from Maiza to the next fertilization).

For example, in animals (in the figure on the left), only gametes, in plants (in the picture in the center) there is a diploid generation ( sporophyte) and the haploid generation ( gametofit), while many unicellites prevail the haploid phase, and the zygota after fertilization is divided by meiosis, as a result of which haploid cells are obtained again.

Life cycles of plants.

W. lower plants All the above types of life cycles are found. Thus, the predominance of diplophase is characteristic of Fukus (hydrochlorus, diatomas and some green algae (codium, alert). Hammetophyte and sporophyte are available, for example, in porphyra (red algae), laminaria (hydrochlorus drum), ulvy (green algae). Finally, the chlammedonads, hares and spirogiirs prevailing gapophase, and the only diploid stage in the life cycle is the zygote.

Higher plants in the life cycle are presented as Gametophyte and sporophyte. Mids usual green plants are haploid. The organs of sexual reproduction are formed: anteriain which numerous spermatozoa are formed, and archegonia, Each of which has one egg cell. The resulting gamets after fertilization give the beginning of the diploid stage, which develops directly on the haploid. Sporophyte MKOs consists of gaustoriawith the help of which it is attached to the gametophyte, legs and boxes. Sporophyte Mukhov is not capable of photosynthesis and lives due to the haploid part of the plant, therefore usually has brown color. Inside the box, many cells are divided by meyosis, forming haploid disputes. Disputes give rise to new green haploid plants. Thus, the prevailing stage in the life cycle of Movov is a haploid.

The main life stage at vascular plants (frames, chests, fern, seed) - diploid. On the leaves of ferns or in special structures at the horsages and planes, sporangies are formed, in which small unicellular disputes are formed as a result of meiosis. Split and falling into suitable conditions, they give the beginning of the haploid stage - zapost. Alterias and Archegony are formed on the overproofs, gametes are formed, fertilization occurs, and a diploid plant is developing from the zygote.

In seed plants, an independent haploid stage does not exist, it is represented by groups of cells developing in special organs of diploid parental organisms. Some time separately there is only a male gamemarketophyte in the form pollen grainBut in it at this time does not occur noticeable processes of vital activity. Female Gametophyte of gone plants is primary endosperm, in flower plants with a reduced female gamethophyt is germ bag. After fertilization, the new diploid organism has been developing from the zygota, the first stages of development also under the protection of the parent organism.

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