Stages of evolution. Stages of the evolution of the plant world The emergence of plants on earth
- What plants are classified as lower? What is their difference from the higher ones?
- Which group of plants currently occupies a dominant position on our planet?
Methods for studying ancient plants. The world of modern plants is diverse (Fig. 83). But in the past, the plant world of the Earth was completely different. Paleontology helps us trace the picture of the historical development of life from its beginning to the present day (from the Greek words “palaios” - ancient, “he/ontos” - existing and “logos”) - the science of extinct organisms, their change in time and space .
Rice. 83. Approximate number of species of modern plants
One of the branches of paleontology - paleobotany - studies the fossil remains of ancient plants preserved in layers of geological sediments. It has been proven that over the centuries the species composition of plant communities has changed. Many plant species died out, others came to replace them. Sometimes plants found themselves in such conditions (in a swamp, under a layer of collapsed rock) that without access to oxygen they did not rot, but were saturated with minerals. Petrification occurred. Petrified trees are often found in coal mines. They are so well preserved that their internal structure can be studied. Sometimes imprints remain on hard rocks, from which one can judge the appearance of ancient fossil organisms (Fig. 84). Spores and pollen found in sedimentary rocks can tell scientists a lot. Using special methods, it is possible to determine the age of fossil plants and their species composition.
Rice. 84. Imprints of ancient plants
Change and development flora . Fossil remains of plants indicate that in ancient times the plant world of our planet was completely different from what it is now.
In the most ancient layers of the earth's crust, it is not possible to find signs of living organisms. In later sediments, remains of primitive organisms are found. The younger the layer, the more often more complex organisms are found, which become increasingly similar to modern ones.
Many millions of years ago there was no life on Earth. Then the first primitive organisms appeared, which gradually changed and transformed, giving way to new, more complex ones.
In the process of long-term development, many plants on Earth disappeared without a trace, others changed beyond recognition. Therefore, it is very difficult to completely restore the history of the development of the plant world. But scientists have already proven that all modern plant species descended from more ancient forms.
Initial stages of development of the plant world. The study of the oldest layers of the earth's crust, imprints and fossils of previously living plants and animals, and many other studies have made it possible to establish that the Earth was formed more than 5 billion years ago.
The first living organisms appeared in water approximately 3.5-4 billion years ago. The simplest single-celled organisms were similar in structure to bacteria. They did not yet have a separate nucleus, but they had a metabolic system and the ability to reproduce. They used organic and mineral substances dissolved in the water of the primary ocean for food. Gradually, the supply of nutrients in the primary ocean began to deplete. A fight for food began between the cells. Under these conditions, some cells developed a green pigment - chlorophyll, and they adapted to the use of energy sunlight to convert water into food and carbon dioxide. This is how photosynthesis arose, that is, the process of formation of organic substances from inorganic ones using light energy. With the advent of photosynthesis, oxygen began to accumulate in the atmosphere. The composition of the air began to gradually approach the modern one, that is, it mainly includes nitrogen, oxygen and a small amount of carbon dioxide. This atmosphere contributed to the development of more advanced forms of life.
The appearance of algae. Single-celled algae evolved from the ancient simplest unicellular organisms capable of photosynthesis. Single-celled algae are the ancestors of the plant kingdom. Along with floating forms, those attached to the bottom also appeared among the algae. This way of life led to the division of the body into parts: some of them serve for attachment to the substrate, others carry out photosynthesis. In some green algae, this was achieved thanks to a giant multinucleate cell, divided into leaf-shaped and root-shaped parts. However, the division of the multicellular body into parts that perform different functions turned out to be more promising.
The occurrence of sexual reproduction in algae was important for the further development of plants. Sexual reproduction contributed to the variability of organisms and their acquisition of new properties that helped them adapt to new living conditions.
Plants coming to land. The surface of continents and the ocean floor have changed over time. New continents rose and existing ones sank. Due to vibrations of the earth's crust, land appeared in place of the seas. The study of fossil remains shows that the plant world of the Earth also changed.
The transition of plants to a terrestrial lifestyle was apparently associated with the existence of land areas that were periodically flooded and cleared of water. The drainage of these areas occurred gradually. Some algae began to develop adaptations for living outside of water.
At this time, the globe had a humid and warm climate. The transition of some plants from an aquatic to a terrestrial lifestyle began. The structure of ancient multicellular algae gradually became more complex, and they gave rise to the first land plants (Fig. 85).
Rice. 85. The first sushi plants
One of the first terrestrial plants were rhiniophytes that grew along the banks of reservoirs, for example rhinia (Fig. 86). They existed 420-400 million years ago and then died out.
Figure 86. Rhiniophytes
The structure of rhinophytes still resembled the structure of multicellular algae: there were no real stems, leaves, roots, they reached a height of about 25 cm. The rhizoids, with the help of which they attached to the soil, absorbed water and mineral salts from it. Along with the similarity of roots, stems and primitive conducting systems, rhiniophytes had integumentary tissue that protected them from drying out. They reproduced by spores.
Origin of higher spore plants. From rhiniophyte-like plants came the ancient mosses, horsetails and ferns and, apparently, mosses, which already had stems, leaves, and roots (Fig. 87). These were typical spore plants; they reached their heyday about 300 million years ago, when the climate was warm and humid, which favored the growth and reproduction of ferns, horsetails and mosses. However, their emergence onto land and separation from the aquatic environment was not yet final. During sexual reproduction, spore plants require an aquatic environment for fertilization.
Rice. 87. Origin of higher plants
Development of seed plants. At the end of the Carboniferous period, the Earth's climate almost everywhere became drier and colder. Tree ferns, horsetails and mosses gradually died out. Primitive gymnosperms appeared - descendants of some ancient fern-like plants.
Living conditions continued to change. Where the climate became more severe, ancient gymnosperms gradually died out (Fig. 88). They were replaced by more advanced plants - pine, spruce, fir.
Plants that reproduced by seeds were better adapted to life on land than plants that reproduced by spores. This is due to the fact that the possibility of fertilization in them does not depend on the availability of water in external environment. The superiority of seed plants over spore plants became especially clear when the climate became less humid.
Angiosperms appeared on Earth about 130 million years ago.
Angiosperms turned out to be the most adapted plants for life on land. Only angiosperms have flowers; their seeds develop inside the fruit and are protected by the pericarp. Angiosperms quickly spread throughout the Earth and occupied all possible habitats. For more than 60 million years, angiosperms have dominated the Earth.
Having adapted to different living conditions, angiosperms created a diverse plant cover of the Earth from trees, shrubs and grasses.
New concepts
Paleontology. Paleobotany. Rhiniophytes
Questions
- Based on what data can we say that the plant world developed and became more complex gradually?
- Where did the first living organisms appear?
- What was the significance of the advent of photosynthesis?
- Under the influence of what conditions did ancient plants switch from an aquatic lifestyle to a terrestrial one?
- Which ancient plants gave rise to ferns, and which to gymnosperms?
- What is the advantage of seed plants over spore plants?
- Compare gymnosperms and angiosperms. What structural features provided angiosperm plants with an advantage?
Quests for the curious
In summer, explore the steep banks of rivers, the slopes of deep ravines, quarries, coal, limestone. Find fossilized ancient organisms or their imprints.
Sketch them. Try to determine which ancient organisms they belong to.
Do you know that...
The oldest imprint of plant flowers was found in Colorado (USA) in 1953. The plant looked like a palm tree. The imprint is 65 million years old.
Some forms of ancient angiosperms: poplars, oaks, willows, eucalyptus, palm trees - have survived to this day.
The Plant Kingdom is surprisingly diverse. It includes algae, mosses, mosses, horsetails, ferns, gymnosperms and angiosperms (flowering) plants.
Lower plants - algae - have a relatively simple structure. They can be unicellular or multicellular, but their body (thallus) is not divided into organs. There are green, brown and red algae. They produce huge amounts of oxygen, which not only dissolves in water, but is also released into the atmosphere.
Man uses seaweed in chemical industry. From them we obtain iodine, potassium salts, cellulose, alcohol, acetic acid and other products. In many countries, seaweed is used to prepare a variety of dishes. They are very useful, as they contain a lot of carbohydrates, vitamins, and are rich in iodine.
Lichens consist of two organisms - a fungus and an algae, which are in complex interaction. Lichens play in nature important role, being the first to settle in the most barren places. When they die, they form soil on which other plants can live.
Higher plants are called mosses, mosses, horsetails, ferns, gymnosperms and angiosperms. Their body is divided into organs, each of which performs specific functions.
Mosses, mosses, horsetails, and ferns reproduce by spores. They are classified as higher spore plants. Gymnosperms and angiosperms are higher seed plants.
Angiosperms have the most high organization. They are widespread in nature and are the dominant group of plants on our planet.
Almost all agricultural plants grown by humans are angiosperms. They provide people with food, raw materials for various industries industry, used in medicine.
The study of fossil remains proves the historical development of the plant world over many millions of years. The first plants to appear were algae, which evolved from simpler organisms. They lived in the water of the seas and oceans. Ancient algae gave rise to the first land plants - rhiniophytes, from which came mosses, horsetails, mosses and ferns. Ferns reached their heyday in the Carboniferous period. With climate change, they were replaced first by gymnosperms and then by angiosperms. Angiosperms are the most numerous and highly organized group of plants. It has become dominant on Earth.
As a result of prehistoric events such as the Permian and Cretaceous–Paleogene, many plant families and some ancestors of extant species became extinct before recorded history began.
The general trend of diversification includes four main groups of plants that dominate the planet from the Middle Silurian period to the present:
Zosterophyllum model
- The first main group, representing terrestrial vegetation, included seedless vascular plants, represented by the rhinium classes ( Rhynophyta), zosterophylls ( Zosterophyllopsida).
Ferns
- The second main group, which appeared in the late Devonian period, consisted of ferns.
- The third group, seed plants, appeared at least 380 million years ago. It included gymnosperms ( Gymnospermae), which dominated the terrestrial flora during most of the Mesozoic era until 100 million years ago.
- The last fourth group, the angiosperms, appeared about 130 million years ago. The fossil record also shows that this group of plants was abundant in most areas of the world between 30 million and 40 million years ago. Thus, angiosperms dominated the Earth's vegetation for almost 100 million years.
Palaeozoic
Moss-moss
The Proterozoic and Archean eons precede the appearance of terrestrial flora. Seedless, vascular, terrestrial plants appeared in the mid-Silurian period (437-407 million years) and were represented by rhinophytes and possibly lycophytes (including Lycopodium). From primitive rhyniophytes and lycophytes, land vegetation evolved rapidly during the Devonian period (407-360 million years ago).
The ancestors of true ferns may have evolved in the mid-Devonian. During the late Devonian period, horsetails and gymnosperms appeared. By the end of the period, all the main divisions of vascular plants, except angiosperms, already existed.
The development of the characteristics of vascular plants, during the Devonian, allowed an increase in the geographical diversity of the flora. One of them was the appearance of flattened leaves, which increased efficiency. Another is the emergence of secondary wood, allowing plants to greatly increase in shape and size, leading to trees and probably forests. The gradual process was the reproductive development of the seed; the earliest was found in Upper Devonian deposits.
The ancestors of conifers and cycads appeared in the Carboniferous period (360-287 million years ago). During the Early Carboniferous in high and middle latitudes, vegetation shows dominance of Lycopodium and Progymnospermophyta.
Progymnospermophyta
In the lower latitudes of North America and Europe, a wide variety of Lycopodiums and Progymnospermophyta, as well as other vegetation. There are seed ferns (including calamopityales), along with true ferns and horsetails ( Archaeocalamites).
Late Carboniferous vegetation at high latitudes was severely damaged by the onset of the Permian-Carboniferous Ice Age. In the northern mid-latitudes, the fossil record shows the dominance of horsetails and primitive seed ferns (pteridosperms) over few other plants.
In the northern low latitudes, the land masses of North America, Europe and China were covered by shallow seas or marshes and, because they were close to the equator, experienced tropical and subtropical climate conditions.
At this time, the first ones known as coal forests appeared. Great amount peat was established as a result of favorable year-round growth conditions and the adaptation of giant Lycopodium to tropical wetland environments.
In the drier areas surrounding the lowlands, forests of horsetails, seed ferns, cordaites and other ferns existed in great abundance.
The Permian period (287-250 million years ago) indicates a significant transition of conifers, cycads, glossopteris, gigantopterids and peltasperms from poor fossil record in the Carboniferous to significant abundant vegetation. Other plants, such as tree ferns and giant lycopodiums, were present in the Permian, but not in abundance.
As a result of the Permian mass extinction, tropical swamp forests disappeared, and with them the Lycopodiums; Cordaites and Glossopteris became extinct at higher latitudes. About 96% of all plant and animal species disappeared from the face of our planet at this time.
Mesozoic era
At the beginning of the Triassic period (248-208 million years ago), the sparse fossil record indicates a decline in the Earth's flora. From the mid to late Triassic, modern families of ferns, conifers, and a now extinct group of plants, the Bennettites, inhabited most terrestrial environments. After the mass extinction, Bennettites moved into vacant ecological niches.
Late Triassic flora in equatorial latitudes includes a wide range of ferns, horsetails, cycads, bennettites, ginkgos and conifers. Plant combinations in low latitudes are similar, but not rich in species. This lack of plant variation at low and mid-latitudes reflects a global frost-free climate.
In the Jurassic period (208-144 million years ago), terrestrial vegetation similar to modern flora appeared, and modern families can be considered descendants of ferns of this geological period of time , such as Dipteridaceae, Matoniaceae, Gleicheniaceae, and Cyatheaceae.
Conifers of this age may also include modern families: podocarpaceae, araucariaceae, pine and yew. These conifers, during the Mesozoic, created significant deposits of such things as coal.
During the Early and Middle Jurassic period, a variety of vegetation grew in the equatorial latitudes of western North America, Europe, Central Asia and the Far East. It included: horsetails, cycads, bennettites, ginkgos, ferns and coniferous trees.
Warm, humid conditions also existed in the northern mid-latitudes (Siberia and northwestern Canada), supporting ginkgo forests. Deserts were found in the central and eastern parts of North America and North Africa, and the presence of Bennettites, cycads, Cheirolepidiaceae and conifers indicated the adaptation of plants to arid conditions.
Southern latitudes had similar vegetation to equatorial latitudes, but due to drier conditions, conifers were abundant and ginkgos were scarce. Southern flora has spread to very high latitudes, including Antarctica, due to the lack polar ice.
Cheirolipidae
During the Cretaceous period (144-66.4 million years ago) in South America, Central and North Africa, and Central Asia there were dry, semi-desert natural conditions. Thus, the terrestrial vegetation was dominated by Cheirolipidium conifers and Matoniaceae ferns.
The northern mid-latitudes of Europe and North America had more diverse vegetation consisting of Bennettites, cycads, ferns and conifers, while the southern mid-latitudes were dominated by Bennettites.
The Late Cretaceous saw significant changes in the Earth's vegetation, with the emergence and spread of flowering seed plants, the angiosperms. The presence of angiosperms meant the end of the typical Mesozoic flora dominated by gymnosperms and a definite decline in the Bennettites, Ginkgoaceae and Cycads.
Nothofagus or southern beech
During the Late Cretaceous, arid conditions prevailed in South America, central Africa and India, resulting in palm trees dominating tropical vegetation. The mid-southern latitudes were also influenced by deserts, and the plants that bordered these areas included: horsetails, ferns, conifers and angiosperms, particularly nothofagus (southern beech).
Sequoia Hyperion
High latitude areas were devoid of polar ice; Due to warmer climate conditions, angiosperms were able to thrive. The most diverse flora was found in North America, where evergreens, angiosperms and conifers, especially redwood and sequoia, were present.
The Cretaceous-Paleogene mass extinction (C-T extinction) occurred about 66.4 million years ago. This is an event that suddenly caused global climate change and the extinction of many animal species, especially dinosaurs.
The greatest “shock” to terrestrial vegetation occurred in the mid-latitudes of North America. Pollen and spore counts are slightly higher borders K-T the fossil record shows a predominance of ferns and evergreens. Subsequent plant colonization in North America shows a predominance of deciduous plants.
Cenozoic era
Increased rainfall at the beginning of the Paleogene-Neogene (66.4-1.8 million years ago) contributed to the widespread development of rain forests in the southern regions.
Notable during this period was the Arcto polar forest flora found in northwestern Canada. Mild, humid summers alternated with continuous winter darkness with temperatures ranging from 0 to 25°C.
Birch Grove
These climatic conditions supported deciduous vegetation, which included sycamore, birch, moonsperm, elm, beech, magnolia; and gymnosperms such as Taxodiaceae, Cypressaceae, Pinaceae and Ginkgoaceae. This flora spread throughout North America and Europe.
Approximately eleven million years ago, during the Miocene Epoch, marked changes in vegetation occurred with the emergence of grasses and their subsequent expansion into grassy plains and prairies. The appearance of this widespread flora contributed to the development and evolution of herbivorous mammals.
The Quaternary period (1.8 million years ago to the present) began with continental glaciation in northwestern Europe, Siberia and North America. This glaciation affected land vegetation, with flora migrating north and south in response to glacial and interglacial fluctuations. During interglacial periods, maple, birch and olive trees were common.
The final migrations of plant species at the end of the last Ice Age (about eleven thousand years ago) shaped the modern geographic distribution of land flora. Some areas, such as mountain slopes or islands, have unusual species distributions as a result of their isolation from global plant migration.
1. Specify correct sequence appearance of organisms on Earth.
1) algae – bacteria – mosses – ferns – gymnosperms – angiosperms
2) bacteria – algae – mosses – ferns – angiosperms – gymnosperms
3) bacteria – algae – mosses – ferns – gymnosperms – angiosperms
4) algae – mosses – ferns – bacteria – gymnosperms – angiosperms
2. Establish the sequence of appearance of the main groups of plants on Earth in the process of evolution.
1) psilophytes
2) unicellular green algae
3) multicellular green algae
3. Establish the sequence of complication of organisms in the process of historical development of the organic world on Earth.
1) formation of chlorophyll in cells
2) the appearance of rhizoids
3) fruit formation
4) the appearance of roots, stems, leaves
5) the emergence of unicellular heterotrophic organisms
4. Establish the sequence of increasing complexity of the organization of organisms in the process of historical development of the organic world on Earth.
1) the emergence of photosynthesis
2) development of seeds in cones
3) the occurrence of double fertilization
4) the emergence of heterotrophic organisms
5) participation of oxygen in metabolic processes in cells
5. In connection with the emergence of the first plants on land, they developed
1) vegetative organs 2) seeds 3) spores 4) gametes
6. What feature of flowering plants contributed to their widespread distribution in the Cenozoic era?
1) the presence of flowers and fruits
2)increasing life expectancy
3)variety vegetative organs
4) the appearance of various plastids
1) the seeds contain an embryo with a supply of nutrients
2) animals eat seeds
3) seeds are spread by the wind
4) the seeds lie openly on the scales of the cones
8. Ancient ferns became extinct in the process of evolution because
1) they were destroyed by animals
2) they were intensively used by ancient man
3) there was a cooling and a decrease in air humidity
4) flowering plants appeared
9. The evolution of plants went in the direction
1)reduced life expectancy
2)development of new environments and habitats
3) maintaining the dependence of fertilization on water
4) preservation of the gametophyte as the main stage of development
10. Which of the listed groups of plants was the first during evolution to cease to depend on the availability of water for fertilization?
11. Mammals evolved from the ancients
1) dinosaurs 2) animal-toothed lizards
3) lobe-finned fish 4) tailed amphibians
12. The picture shows a print of Archeopteryx. It is a fossil transitional form between the ancient
1)birds and mammals
2) reptiles and birds
3) reptiles and mammals
4) amphibians and birds
13. What sign indicates the relationship of Archeopteryx with modern birds?
1) fingers with claws on the forelimbs
2) shank in hind limbs
3) small teeth in the jaws
4) caudal region in the spine
14. What ancient fish did amphibians originate from?
1) sharks and rays 2) sturgeons and belugas 3) lozenges 4) bonefish
15. Many scientists consider it a fossil transitional form between the ancients
1) fish and amphibians 2) reptiles and birds
3) fish and reptiles 4) amphibians and birds
16. In the process of evolution, the appearance of a five-fingered limb in animals is associated with
1) transition to a terrestrial lifestyle
2) the need to climb trees
3) the need to make tools
4) active movement in the water column
17. Dismembered limbs in animals were formed in the process of evolution as an adaptation to movement in
1) water 2) air 3) soil 4) ground-air environment
18. In the process of evolution, the emergence of a second circle of blood circulation in animals led to the emergence
1) gill respiration 2) pulmonary respiration
3) tracheal breathing 4) breathing over the entire surface of the body
19. The most likely ancestors of reptiles were
1) newts 2) archeopteryx
3) ancient amphibians 4) lobe-finned fish
20. Which ancient animals are considered the ancestors of reptiles?
1) ichthyosaurs 2) archeopteryx
3) stegocephali 4) lobe-finned fish
21. In what era did reptiles dominate on Earth:
1) Mesozoic 2) Archean
3) Cenozoic 4) Paleozoic
22. From ancient reptiles came:
1) birds and mammals 2) lungfishes and molluscs
3) coelenterates and worms 4) fish and amphibians
23. Establish the hypothetical sequence of occurrence of the following groups of animals:
A) Flying insects
B) Reptiles
B) Primates
G) Annelids
D) Flatworms
E) Coelenterates
24. Establish the sequence of stages in the development of the animal world of the Earth from the most ancient to the modern:
A) the appearance of stegocephals
B) dominance of marine invertebrates
B) reptilian dominance
D) the appearance of cartilaginous fish
D) the appearance of bony fish
25. Establish the sequence of increasing complexity of animal organization in the process of historical development of the organic world on Earth. Write down the corresponding sequence of numbers in your answer.
1) the appearance of the cortex in cerebral hemispheres
2) formation of chitinous cover
3) the emergence of radial symmetry of the body
4) development of the intestine with oral and anal openings
5) appearance of jaws in the skull
The book outlines a pressing problem of modern natural science - the origin of life. It is written on the basis of the most modern data from geology, paleontology, geochemistry and cosmochemistry, which refutes many traditional but outdated ideas about the origin and development of life on our planet. The extreme antiquity of life and the biosphere, commensurate with the age of the planet itself, allows the author to conclude: the origin of the Earth and life is a single interconnected process.
For readers interested in geosciences.
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Plants, as typical representatives of photoautotrophic organisms of our planet, arose during a long evolution, which originates from the primitive inhabitants of the illuminated zone of the sea - planktonic and benthic prokaryotes. By comparing paleontological data with data on the comparative morphology and physiology of living plants, it is possible to general view outline the following chronological sequence of their appearance and development:
1) bacteria and blue-green algae (prokaryotes);
2) cyan, green, brown, red, etc. algae (eukaryotes, like all subsequent organisms);
3) mosses and liverworts;
4) ferns, horsetails, mosses, seed ferns;
6) angiosperms, or flowering plants.
Bacteria and blue-green algae were found in the most ancient preserved deposits of the Precambrian; algae appeared much later, and only in the Phanerozoic do we encounter the lush development of higher plants: lycophytes, horsetails, gymnosperms and angiosperms.
Throughout the Cryptozoic period, predominantly single-celled organisms—various types of algae—developed in primary reservoirs in the euphotic zone of ancient seas.
The main representatives of prokaryotes discovered in the Precambrian had autotrophic nutrition - through photosynthesis. Most favorable conditions for photosynthesis were created in the illuminated part of the sea at a depth from the surface to 10 m, which also corresponded to the conditions of shallow-water benthos.
To date, the study of Precambrian microfossils has advanced, and accordingly, a large amount of factual material has been accumulated. In general, the interpretation of microscopic specimens is a difficult task that cannot be resolved unambiguously.
Trichome bacteria, which differ sharply from mineral formations of a similar shape, are best identified and identified. The obtained empirical material on microfossils allows us to conclude that they can be compared with living cyanobacteria.
Stromatolites, as biogenic structures of the distant past of the planet, were formed during the accumulation of a thin sediment of calcium carbonate captured by photosynthetic organisms of microbiological associations. Microfossils in stromatolites consist almost exclusively of prokaryotic microorganisms, mainly related to blue-green algae - cyanophytes. When studying the remains of benthic microorganisms composing stromatopites, one thing became clear: interesting feature, which is of fundamental importance. Microfossils of different ages change little in their morphology and generally indicate the conservatism of prokaryotes. Microfossils related to prokaryotes remained almost constant for quite some time. for a long time. In any case, we have before us an established fact - the evolution of prokaryotes was much slower than that of higher organisms.
So, in the course of geological history, prokaryotic bacteria exhibit maximum persistence. Persistent forms include organisms that have been preserved unchanged during the process of evolution. As G. A. Zavarzin notes, since ancient communities of microorganisms show significant similarities with modern ones developing in hydrotherms and in areas of evaporite formation, this makes it possible to more thoroughly study the geochemical activity of these communities using modern natural and laboratory models, extrapolating them to the distant Precambrian time.
The first eukaryotes arose in planktonic associations of open waters. The end of the exclusive dominance of prokaryotes dates back to approximately 1.4 billion years ago, although the first eukaryotes appeared much earlier. Thus, according to the latest data, the appearance of fossil organic remains from black shales and carbonaceous formations of the Upper Lake region indicates the appearance of eukaryotic microorganisms 1.9 billion years ago.
From the date of 1.4 billion years ago to our time, the Precambrian fossil record expands significantly. The appearance of relatively large forms related to planktonic eukaryotes and called “acritarchs” (translated from Greek as “creatures of unknown origin”) is dated to this date. It should be noted that the acritarcha group is proposed as an undefined systematic category denoting Microfossils of different origins, but similar in external morphological characters. Acritarchs from the Precambrian and Lower Paleozoic are described in the literature. Most acritarchs were probably single-celled photosynthetic eukaryotes - the shells of some ancient algae. Some of them could still have a prokaryotic organization. The planktonic nature of acritarchs is indicated by their cosmopolitan distribution in sediments of the same age. The most ancient acritarchs from Early Riphean deposits Southern Urals discovered by T.V. Yankauskas.
Over the course of geological time, the size of acritarchs increased. According to observational data, it turned out that the younger the Precambrian Microfossils, the larger they are. It is assumed that a significant increase in the size of acritarchs was associated with an increase in the size of the eukaryotic cell organization. They could have appeared as independent organisms or, more likely, in symbiosis with others. L. Margelis believes that eukaryotic cells were assembled from pre-existing prokaryotic cells. However, for the survival of eukaryotes, it was necessary that the habitat be saturated with oxygen and, as a consequence, aerobic metabolism arose. Initially, free oxygen released during photosynthesis of cyanophytes accumulated in limited quantities in shallow water habitats. The increase in its content in the biosphere caused a reaction on the part of organisms: they began to populate oxygen-free habitats (in particular, anaerobic forms).
Data from Precambrian micropaleontology indicate that in the Middle Precambrian, even before the appearance of eukaryotes, cyanophytes constituted a relatively small part of the plankton. Eukaryotes needed free oxygen and increasingly competed with prokaryotes in those areas of the biosphere where free oxygen appeared. Based on available micropaleontological data, it can be judged that the transition from prokaryotic to eukaryotic flora of ancient seas occurred slowly and both groups of organisms coexisted together for a long time. However, this coexistence occurs in a different proportion in the modern era. By the beginning of the Late Riphean, many autotrophic and heterotrophic forms of organisms had already spread.
As organisms developed, they moved across nutrients to deeper and more distant areas of the sea. The fossil record notes a sharp increase in the diversity of large spheroidal forms of eukaryotic acritarchs in Late Riphean times, 900-700 million years ago. About 800 million years ago, representatives of a new class of planktonic organisms appeared in the World Ocean - goblet-shaped bodies with massive shells or outer covers mineralized with calcium carbonate or silica. At the beginning of the Cambrian period, significant shifts occurred in the evolution of plankton - a variety of microorganisms arose with a complex sculptured surface and improved buoyancy. They gave rise to true spiny acritarchs.
The appearance of eukaryotes created an important prerequisite for the emergence of multicellular plants and animals in the Early Riphean (about 1.3 billion years ago). For the Belta series from the Precambrian of the western states of North America, they were described by C. Walcott. But what type of algae they belong to (brown, green or red) is still unclear. Thus, the extremely long era of dominance of bacteria and related blue-green algae was replaced by an era of algae that reached a significant variety of shapes and colors in the waters of the ancient oceans. During the Late Riphean and Vendian, multicellular algae became more diverse; they were compared with brown and red algae.
According to Academician B.S. Sokolov, multicellular plants and animals appeared almost simultaneously. In Vendian deposits there are various representatives aquatic plants. The most prominent place is occupied by multicellular algae, the thalli of which often overflow the strata of Vendian sediments: mudstones, clays, sandstones. Macroplanktonic algae, colonial algae, spiral-filamentous algae Volymella, felt algae and other forms are often found. Phytoplankton is very diverse.
For most of Earth's history, plant evolution took place in aquatic environments. It was here that aquatic vegetation originated and went through various stages of development. In general, algae are a large group of lower aquatic plants that contain chlorophyll and produce organic matter through photosynthesis. The body of the algae has not yet been differentiated into roots, leaves and other characteristic parts. They are represented by unicellular, multicellular and colonial forms. Reproduction is asexual, vegetative and sexual. Algae are part of plankton and benthos. Currently, they are classified as a plant subkingdom Thallophyta, in which the body is composed of a relatively uniform tissue - thallus, or Thallus. The thallus consists of many cells that are similar in appearance and function. In the historical aspect, algae went through the longest stage in the development of green plants and, in the general geochemical cycle of matter in the biosphere, played the role of a giant generator of free oxygen. The emergence and development of algae was extremely uneven.
Green algae (Chlorophyta) are a large and widespread group of predominantly green plants, which falls into five classes. By appearance they are very different from each other. Green algae come from green flagellated organisms. This is evidenced by transitional forms - pyramidomonas and chlamydomonas, mobile unicellular organisms that live in waters. Green algae reproduce sexually. Some groups of green algae achieved great development during the Triassic period.
Flagellates (Flagellata) are grouped into a group of microscopic unicellular organisms. Some researchers attribute them to the plant kingdom, others to the animal kingdom. Like plants, some flagellates contain chlorophyll. However, unlike most plants, they do not have a separate cellular system and are able to digest food with the help of enzymes, and also live in the dark, like animal organisms. In all likelihood, flagellates existed in the Precambrian, but their undisputed representatives were found in Jurassic deposits.
Brown algae (Phaeophyta) are distinguished by the presence of brown pigment in such quantities that it actually masks chlorophyll and gives plants the appropriate color. Brown algae belong to benthos and plankton. The largest algae reach 30 m in length. Almost all of them grow in salt water, which is why they are called sea grass. Brown algae include sargassum algae - floating planktonic forms with a large number of bubbles. In fossil form they are known from the Silurian.
Red algae(Rhodophyta) have this color due to the red pigment. These are predominantly marine plants, highly branched. Some of them have a calcareous skeleton. This group is often called cullipora. They exist today, and have been known in fossil form since the Lower Cretaceous. Somipores, which are close to them, with larger and wider cells, appeared in the Ordovician.
Charovaya algae(Charophyta) are a very unique and rather highly organized group of multicellular plants that reproduce sexually. They are so different from other algae that some botanists classify them as leaf-stem algae due to the emerging tissue differentiation. Charodic algae are green in color and currently live in fresh water and in brackish water bodies. They avoid seawater with normal salinity, but it can be assumed that in the Paleozoic they inhabited the seas. Some charophytes develop spores impregnated with calcium carbonate. Characeae are among the important rock-forming organisms of freshwater limestones.
Diatoms(Diatomeae) - typical representatives of plankton. They have an oblong shape and are covered on the outside with a shell made of silica. The first remains of diatoms were found in Devonian sediments, but they may be older. Generally diatoms relatively young group. Their evolution has been studied better than other algae, since flint shells and valves of diatoms can be preserved in a fossil state for a very long time. In all likelihood, diatoms are descended from flagellates, which are yellow in color and are capable of depositing small amounts of silica in their shells. In modern times, diatoms are widespread in fresh and sea waters, are occasionally found in moist soils. Remains of diatoms are known in Jurassic deposits, but it is possible that they appeared much earlier. Fossil diatoms from the Early Cretaceous reached the modern era without interruption in sedimentation.
Very important event, which contributed to a sharp acceleration in the rate of evolution of the entire living population of our planet, was the emergence of plants from the marine environment onto land. The appearance of plants on the surface of the continents can be considered a true revolution in the history of the biosphere. The development of terrestrial vegetation created the prerequisites for animals to reach land. However, the massive transition of plants to land was preceded by a long preparatory period. It can be assumed that plant life on land appeared a very long time ago, at least locally - in a humid climate on the coasts of shallow bays and lagoons, where changes in water level periodically brought aquatic vegetation onto land. The Soviet naturalist L. S. Berg was the first to express the idea that the land surface was not a lifeless desert neither in the Cambrian nor in the Precambrian. The prominent Soviet paleontologist L. Sh. Davitashvili also admitted that in the Precambrian the continents probably already had some kind of population consisting of low-organized plants and, possibly, even animals. However, their total biomass was negligible.
To live on land, plants had to not lose water. It should be borne in mind that in higher plants - mosses, pteridophytes, gymnosperms and flowering plants, which currently make up the bulk of terrestrial vegetation, only roots, root hairs and rhizoids come into contact with water, while the rest of their organs are in the atmosphere and evaporate water the entire surface.
Plant life flourished most on the shores of lagoon lakes and swamps. Here a type of plant appeared, the lower part of which was in the water, and the upper part in the air, under direct rays of the sun. Somewhat later, with the penetration of plants onto unflooded land, their very first representatives developed root system and were able to consume groundwater. This contributed to their survival during dry periods. Thus, new circumstances led to the division of plant cells into tissues and the development of protective devices that did not exist in the ancestors that lived in water.
Fig. 14. Development and genetic connections various groups of land plants
The massive conquest of the continents by plants occurred during the Silurian period of the Paleozoic era. First of all, these were psilophytes - peculiar spore-bearing plants resembling club mosses. Some of the twisting stems of psilophytes were covered with bristly leaves. Psilophytes were devoid of roots, and mostly leaves. They consisted of branching green stems up to 23 cm high and rhizomes stretching horizontally in the soil. Psilophytes, as the first reliable sushi plants, created entire green carpets on moist soil.
Probably, the production of organic matter from the first land vegetation was insignificant. The vegetation of the Silurian period undoubtedly originated from the algae of the sea and itself gave rise to the vegetation of the subsequent period.
After the conquest of the land, the development of vegetation led to the formation of numerous and varied forms. Intensive separation of plant groups began in the Devonian and continued in subsequent geological time. The general pedigree of the most important plant groups is given in Fig. 14.
Mosses originated from. seaweed Their early stage of development is very similar to some green algae. However, there is an assumption that mosses originated from simpler representatives of brown algae, adapted to life on damp rocks or in soils in general.
On the surface of the Early Paleozoic continents, the age of algae gave way to the age of psilophytes, which gave rise to vegetation that was reminiscent in appearance and size of modern thickets of large mosses. The dominance of psilophytes was replaced in the Carboniferous period by the dominance of fern-like plants, which formed fairly extensive forests on marshy soils. The development of these plants contributed to the change in the composition of atmospheric air. A significant amount of free oxygen was added and a mass of nutrients necessary for the emergence and development of land vertebrates accumulated. At the same time, huge masses of coal were accumulated. The Carboniferous period was characterized by an exceptional flourishing of terrestrial vegetation. Tree-like mosses appeared, reaching a height of 30 m, huge horsetails, ferns, and conifers began to appear. During the Permian period, the development of terrestrial vegetation continued, which significantly expanded its habitats.
The period of dominance of ferns gave way to the period of cone-bearing conifers. The surface of the continents began to take on a modern appearance. At the beginning of the Mesozoic era, conifers and cycads became widespread, and flowering plants appeared in the Cretaceous period. At the very beginning of the Early Cretaceous era, Jurassic forms of plants still existed, but then the composition of the vegetation changed greatly. At the end of the Early Cretaceous era there are many angiosperms. From the very beginning of the Late Cretaceous era, they pushed aside gymnosperms and took a dominant position on land. In general, in the terrestrial flora there is a gradual replacement of the Mesozoic vegetation of gymnosperms (conifers, cycads, ginkgos) by vegetation of the Cenozoic appearance. The vegetation of the Late Cretaceous era is already characterized by the presence of a significant number of modern flowering plants such as beech, willow, birch, plane tree, laurel, and magnolia. This restructuring of vegetation prepared a good food base for the development of higher terrestrial vertebrates - mammals and birds. The development of flowering plants was associated with the flourishing of numerous insects that played an important role in pollination.
The onset of a new period in the development of plants did not lead to the complete destruction of the ancient plant forms. Some organisms of the biosphere were preserved. With the advent of flowering plants, bacteria not only did not disappear, but continued to exist, finding new sources of nutrition in the soil and in the organic matter of plants and animals. Seaweed different groups changed and developed along with higher plants.
Coniferous forests, which appeared in the Mesozoic, still grow today along with deciduous ones. They provide shelter to fern-like plants, since these ancient inhabitants of the foggy and humid climate of the Carboniferous period are afraid of open places illuminated by the sun.
Finally, it should be noted that there are persistent forms in the modern flora. The most persistent were separate groups bacteria, virtually unchanged since the early Precambrian. But from more highly organized forms of plants, genera and species were also formed, which have changed little to date.
It should be noted that there is an undoubted presence in the modern flora of relatively highly organized multicellular plant genera. Late Paleozoic and Mesozoic forms of plants, which lived without changes for tens and hundreds of millions of years, are, of course, persistent. Thus, at present, “living fossils” (Fig. 15) from groups of ferns, gymnosperms and clubmosses have been preserved among the plant world. The term “living fossil” was first used by Charles Darwin, citing the East Asian gymnosperm tree as an example Ginkgo biloba. From the world of terrestrial plants, living fossils include the most famous fern palms, ginkgo tree, araucaria, mammoth tree, or sequoia.
As noted by the expert on fossil flora A. N. Krshptofovich, many genera of plants, lords of ancient forests, also existed for an extremely long time, especially in the Paleozoic; for example, Sigillaria, Lepidodendron, Calamites - at least 100-130 million years. The same number - Mesozoic ferns 11 conifers Metasequoia. The genus Ginkgo dates back more than 150 million years, and modern look Ginkgo biloba, if you include the essentially indistinguishable form Ginkgo adiantoides, is about 100 million years old.
Living fossils of the modern plant world can otherwise be called phylogenetically conserved types. Plants that are well studied in paleobotanical terms and classified as living fossils are conservative groups. They have not changed at all or have changed very little compared to related forms of the geological past.
Naturally, the presence of living fossils in modern flora raises the problem of their formation in the history of the biosphere. Conservative organizations are present in all major phylogenetic branches and exist in a wide variety of conditions: in deep and shallow sea zones, in ancient tropical forests, in open steppe expanses and in all bodies of water without exception. The most important condition for the existence of evolutionarily conservative organisms is the presence of habitats with a constant living environment. However, stable living conditions are not decisive. The presence of only certain forms, and not all communities of flora and fauna, indicates other factors in the preservation of living fossils. The study of their geographical distribution indicates that they are confined to strictly defined territories, and are characterized by geographic isolation. Thus, Australia, the islands of Madagascar and New Zealand- These are typical areas of distribution of terrestrial living fossils.
In its evolution, the plant world creates the general appearance of the ancient landscapes in which the development of the animal world took place. Therefore, the division of geological time can be carried out on the basis of the succession of various plant forms. The German paleobotanist W. Zimmermann, back in 1930, divided the entire geological past from the point of view of the development of the plant world into six eras. He gave them a letter designation and arranged them in sequence from ancient eras to younger ones.
A comparison of the usual geological time scale, constructed primarily from paleozoological data, with the plant development scale is presented in Table. eleven.
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STAGES OF EARLY EVOLUTION:
Coacervates (emergence of precellular life forms)
Prokaryotic cells (the emergence of life, cellular life forms - anaerobic heterotrophs)
Chemosynthetic bacteria (emergence of chemosynthesis)
Photosynthetic bacteria (the appearance of photosynthesis, in the future this will lead to the emergence of an ozone screen, which will allow organisms to reach land)
Aerobic bacteria(appearance of oxygen breathing)
Eukaryotic cells (emergence of eukaryotes)
Multicellular organisms
- (exit of organisms to land)
STAGES OF PLANT EVOLUTION:
- (the appearance of photosynthesis in prokaryotes)
Unicellular algae
Multicellular algae
Rhiniophytes, Psilophytes (plant emergence onto land, cell differentiation and appearance of tissues)
Mosses (appearance of leaves and stem)
Ferns, Horsetails, Mosses (appearance of roots)
Angiosperms (appearance of flower and fruit)
STAGES OF ANIMALS EVOLUTION:
Protozoa
Coelenterates (appearance of multicellularity)
Flatworms (the emergence of bilateral symmetry)
Roundworms
Annelids (dismemberment of the body into segments)
Arthropods (the appearance of chitinous cover)
Cranials (formation of notochord, ancestors of vertebrates)
Fish (emergence of the brain in vertebrates)
Lobe-finned fish
Stegocephals (transitional forms between fish and amphibians)
Amphibians (the emergence of lungs and five-fingered limbs)
Reptiles
Oviparous mammals (the emergence of a four-chambered heart)
Placental mammals
ADDITIONAL INFORMATION:
PART 2 ASSIGNMENTS:
Tasks
Establish the sequence of stages characterizing the evolution of the process of reproduction of living organisms. Write down the corresponding sequence of numbers.
1) viviparity in mammals
2) the emergence of simple binary fission of bacteria
3) external fertilization
4) internal fertilization
5) the emergence of conjugation of unicellular
Answer
COACERVATES
1. Establish the sequence of evolutionary processes on Earth in chronological order
1) the emergence of organisms onto land
2) the emergence of photosynthesis
3) formation of an ozone screen
4) formation of coacervates in water
5) the emergence of cellular life forms
Answer
2. Establish the sequence of evolutionary processes on Earth in chronological order
1) the emergence of prokaryotic cells
2) formation of coacervates in water
3) the emergence of eukaryotic cells
4) emergence of organisms onto land
5) the emergence of multicellular organisms
Answer
3. Establish the sequence of processes occurring during the origin of life on Earth. Write down the corresponding sequence of numbers.
1) the appearance of a prokaryotic cell
2) formation of the first closed membranes
3) synthesis of biopolymers from monomers
4) formation of coacervates
5) abiogenic synthesis of organic compounds
Answer
HETEROTROPHES-AUTOTROPHES-EUKARYOTES
1. Establish a sequence reflecting the stages of evolution of protobionts. Write down the corresponding sequence of numbers.
1) anaerobic heterotrophs
2) aerobes
3) multicellular organisms
4) unicellular eukaryotes
5) phototrophs
6) chemotrophs
Answer
2. Establish the sequence of occurrence of groups of organisms in the evolution of the organic world of the Earth in chronological order. Write down the corresponding sequence of numbers.
1) heterotrophic prokaryotes
2) multicellular organisms
3) aerobic organisms
4) phototrophic organisms
Answer
3. Establish the sequence of biological phenomena that occurred in the evolution of the organic world on Earth. Write down the corresponding sequence of numbers.
1) the appearance of aerobic heterotrophic bacteria
2) the emergence of heterotrophic probionts
3) the emergence of photosynthetic anaerobic prokaryotes
4) formation of eukaryotic unicellular organisms
Answer
PLANTS SYSTEM UNITS
1. Establish the chronological sequence in which the main groups of plants appeared on Earth
1) green algae
2) horsetails
3) seed ferns
4) rhiniophytes
5) gymnosperms
Answer
2. Establish the chronological sequence in which the main groups of plants appeared on Earth
1) Psilophytes
2) Gymnosperms
3) Seed ferns
4) Unicellular algae
5) Multicellular algae
Answer
3. Establish the sequence of systematic position of plants, starting with the smallest category. Write down the corresponding sequence of numbers.
1) psilophytes
2) unicellular algae
3) multicellular algae
4) gymnosperms
5) fern-like
6) angiosperms
Answer
Arrange the plants in a sequence that reflects the increasing complexity of their organization during the evolution of the systematic groups to which they belong.
1) Chlamydomonas
2) Psilofite
3) Scots pine
4) Bracken fern
5) Chamomile officinalis
6) Kelp
Answer
AROMORPHOSIS PLANTS
1. Establish the sequence of aromorphoses in the evolution of plants, which determined the appearance of more highly organized forms
1) cell differentiation and tissue appearance
2) appearance of the seed
3) formation of flower and fruit
4) the appearance of photosynthesis
5) formation of the root system and leaves
Answer
2. Establish the correct sequence of occurrence of the most important aromorphoses in plants. Write down the corresponding sequence of numbers.
1) the emergence of multicellularity
2) the appearance of roots and rhizomes
3) tissue development
4) seed formation
5) the emergence of photosynthesis
6) the occurrence of double fertilization
Answer
3. Establish the correct sequence of the most important aromorphoses in plants. Write down the numbers under which they are indicated.
1) Photosynthesis
2) Seed formation
3) The appearance of vegetative organs
4) The appearance of a flower in the fruit
5) The emergence of multicellularity
Answer
4. Establish the sequence of aromorphoses in the evolution of plants. Write down the corresponding sequence of numbers.
1) the appearance of vegetative organs (roots, shoots)
2) appearance of the seed
3) formation of primitive cover tissue
4) flower formation
5) the emergence of multicellular thallus forms
Answer
5. Establish the sequence of processes occurring during the evolution of plants on Earth, in chronological order. Write down the corresponding sequence of numbers in your answer.
1) the emergence of a eukaryotic photosynthetic cell
2) a clear division of the body into roots, stems, leaves
3) landfall
4) the appearance of multicellular forms
Answer
Arrange the structures of plants in the order of their evolutionary origin. Write down the corresponding sequence of numbers.
1) seed
2) epidermis
3) root
4) sheet
5) fruit
6) chloroplasts
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. Which of the listed aromorphoses occurred after plants reached land?
1) occurrence seed propagation
2) the emergence of photosynthesis
3) division of the plant body into stem, root and leaf
4) the occurrence of the sexual process
5) the emergence of multicellularity
6) the appearance of conductive tissues
Answer
CHORDAL AROMORPHOSES
1. Establish the sequence of formation of aromorphoses in the evolution of chordates
1) the appearance of lungs
2) formation of the brain and spinal cord
3) formation of a chord
4) the appearance of a four-chambered heart
Answer
2. Arrange animal organs in the order of their evolutionary origin. Write down the corresponding sequence of numbers.
1) swim bladder
2) chord
3) three-chambered heart
4) uterus
5) spinal cord
Answer
3. Establish the sequence of appearance of aromorphoses in the process of evolution of vertebrates on Earth in chronological order. Write down the corresponding sequence of numbers
1) reproduction by eggs covered with dense shells
2) formation of land-type limbs
3) the appearance of a two-chamber heart
4) development of the embryo in the uterus
5) milk feeding
Answer
4. Establish the sequence of complication of the circulatory system in chordates. Write down the corresponding sequence of numbers.
1) three-chambered heart without a septum in the ventricle
2) two-chamber heart with venous blood
3) there is no heart
4) heart with an incomplete muscular septum
5) in the heart, separation of venous and arterial blood flows
Answer
CHORDAL SYSTEM UNITS
1. Establish the sequence of appearance of groups of chordates in the process of evolution.
1) lobe-finned fish
2) reptiles
3) stegocephals
4) skullless chordates
5) birds and mammals
Answer
2. Establish the sequence of evolutionary phenomena in vertebrates. Write down the corresponding sequence of numbers.
1) the rise of dinosaurs
2) the emergence of primates
3) the flourishing of armored fish
4) the appearance of Pithecanthropus
5) the appearance of stegocephals
Answer
3. Establish the sequence of evolutionary processes of the formation of the main groups of animals that occurred on Earth, in chronological order. Write down the corresponding sequence of numbers
1) Skullless
2) Reptiles
3) Birds
4) Bony fish
5) Amphibians
Answer
4. Establish the sequence of evolutionary processes of the formation of the main groups of animals that occurred on Earth, in chronological order. Write down the corresponding sequence of numbers
1) Skullless
2) Reptiles
3) Birds
4) Bony fish
5) Amphibians
Answer
5. Establish the sequence of evolutionary phenomena in vertebrates. Write down the corresponding sequence of numbers.
1) the appearance of Pithecanthropus
2) the appearance of stegocephals
3) the rise of dinosaurs
4) the flourishing of armored fish
5) the emergence of primates
Answer
ARTHROPODATED AROMORPHOSES
Establish the sequence of formation of aromorphoses in the evolution of invertebrate animals
1) the emergence of bilateral symmetry of the body
2) the appearance of multicellularity
3) the appearance of jointed limbs covered with chitin
4) dismemberment of the body into many segments
Answer
ANIMALS SYSTEMS UNITS
1. Establish the correct sequence of appearance of the main groups of animals on Earth. Write down the numbers under which they are indicated.
1) Arthropods
2) Annelids
3) Skullless
4) Flatworms
5) Coelenterates
Answer
2. Establish in what sequence the types of invertebrate animals should be arranged, taking into account their complexity nervous system in evolution
1) Flatworms
2) Arthropods
3) Coelenterates
4) Annelids
Answer
3. Establish the correct sequence in which these groups of organisms supposedly arose. Write down the corresponding sequence of numbers.
1) Birds
2) Lancelets
3) Ciliates
4) Coelenterates
5) Reptiles
Answer
4. Establish the sequence of appearance of groups of animals. Write down the corresponding sequence of numbers.
1) trilobites
2) Archeopteryx
3) protozoa
4) Dryopithecus
5) lobe-finned fish
6) stegocephals
Answer
5. Establish the geochronological sequence of the emergence of groups of living organisms on Earth. Write down the corresponding sequence of numbers.
1) Flatworms
2) Bacteria
3) Birds
4) Protozoa
5) Amphibians
6) coelenterates
Answer
Establish the sequence of complication of the organization of these animals in the process of evolution
1) earthworm
2) common amoeba
3) white planaria
4) Chafer
5) nematode
6) crayfish
Answer
Choose one, the most correct option. The ozone shield first appeared in the Earth's atmosphere as a result of
1) chemical processes occurring in the lithosphere
2) chemical transformations of substances in the hydrosphere
3) vital activity of aquatic plants
4) vital activity of terrestrial plants
Answer
Choose one, the most correct option. Which type of animal has the most high level organizations
1) Coelenterates
2) Flatworms
3) Annelids
4) Roundworms
Answer
Choose one, the most correct option. Which ancient animals were the most likely ancestors of vertebrates?
1) Arthropods
2) Flatworms
3) Shellfish
4) Skullless
Answer
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