Why do the oceans have "low productivity" in terms of photosynthesis? Cyanobacteria can "short" the process of photosynthesis Threats to marine life

The biosphere (from the Greek "bios" - life, "sphere" - a ball) as a carrier of life arose with the advent of living beings as a result of the evolutionary development of the planet. The biosphere refers to the part of the Earth's shell inhabited by living organisms. The doctrine of the biosphere was created by Academician Vladimir Ivanovich Vernadsky (1863-1945). VI Vernadsky is the founder of the doctrine of the biosphere and the method of determining the age of the Earth by the half-life of radioactive elements. He was the first to reveal the enormous role of plants, animals and microorganisms in the movement of the chemical elements of the earth's crust.

The biosphere has certain boundaries. The upper boundary of the biosphere is located at an altitude of 15-20 km from the Earth's surface. It passes through the stratosphere. The bulk of living organisms is located in the lower air shell - the troposphere. The lowest part of the troposphere (50-70 m) is most populated.

The lower boundary of life passes through the lithosphere at a depth of 2-3 km. Life is concentrated mainly in the upper part of the lithosphere - in the soil and on its surface. The water shell of the planet (hydrosphere) occupies up to 71% of the Earth's surface.

If we compare the size of all geospheres, then we can say that the largest in mass is the lithosphere, the smallest is the atmosphere. The biomass of living beings is small compared to the size of the geospheres (0.01%). In different parts of the biosphere, the density of life is not the same. The largest number of organisms is found near the surface of the lithosphere and hydrosphere. The content of biomass also varies by zone. Tropical forests have the maximum density, the ice of the Arctic and high-mountain regions have an insignificant density.

Biomass. Organisms that make up biomass have an enormous ability to reproduce and spread around the planet (see the section "Struggle for existence"). Reproduction determines density of life. It depends on the size of the organisms and the area required for life. The density of life creates a struggle of organisms for space, food, air, water. In the process of natural selection and adaptability, a large number of organisms with the highest density of life are concentrated in one area.

Land biomass.

On land of the Earth, starting from the poles to the equator, the biomass gradually increases. The greatest concentration and diversity of plants takes place in tropical rainforests. The number and diversity of animal species depends on the plant mass and also increases towards the equator. Food chains, intertwined, form a complex network of chemical elements and energy transfer. Between organisms there is a fierce struggle for the possession of space, food, light, oxygen.

soil biomass. As a living environment, the soil has a number of specific features: high density, small amplitude of temperature fluctuations; it is opaque, poor in oxygen, contains water in which mineral salts are dissolved.

The inhabitants of the soil represent a kind of biocenotic complex. There are many bacteria in the soil (up to 500 t/ha) that decompose the organic matter of fungi; green and blue-green algae live in the surface layers, enriching the soil with oxygen in the process of photosynthesis. The thickness of the soil is permeated with the roots of higher plants, rich in protozoa - amoebae, flagellates, ciliates. Even C. Darwin drew attention to the role of earthworms, which loosen the soil, swallow and saturate it with gastric juice. In addition, ants, ticks, moles, marmots, ground squirrels and other animals live in the soil. All the inhabitants of the soil produce great soil-forming work, participate in the creation of soil fertility. Many soil organisms take part in the general circulation of substances occurring in the biosphere.

Biomass of the oceans.

The Earth's hydrosphere, or the World Ocean, occupies more than 2/3 of the planet's surface. Water has special properties that are important for the life of organisms. Its high heat capacity evens out the temperature of the oceans and seas, mitigating extreme temperature changes in winter and summer. The physical properties and chemical composition of the ocean waters are very constant and create an environment conducive to life. The ocean accounts for about 1/3 of the photosynthesis that occurs on the entire planet.

Single-celled algae and tiny animals suspended in water form plankton. Plankton is of paramount importance in the nutrition of the animal world of the ocean.

In the ocean, in addition to plankton and free-swimming animals, there are many organisms attached to the bottom and crawling along it. The inhabitants of the bottom are called benthos.

In the oceans, living biomass is 1000 times less than on land. In all parts of the oceans there are microorganisms that decompose organic matter into minerals.

Cycle of matter and energy transformation in the biosphere. Plant and animal organisms, being in relationship with the inorganic environment, are included in the cycle of substances and energy that is continuously occurring in nature.

Carbon in nature is found in rocks in the form of limestone and marble. Most of the carbon is in the atmosphere in the form of carbon dioxide. Green plants take in carbon dioxide from the air during photosynthesis. Carbon is included in the circulation due to the activity of bacteria that destroy the dead remains of plants and animals.

When plants and animals decompose, nitrogen is released in the form of ammonia. Nitrophytic bacteria convert ammonia into salts of nitrous and nitric acids, which are absorbed by plants. In addition, some nitrogen-fixing bacteria are able to assimilate atmospheric nitrogen.

Rocks contain large reserves of phosphorus. When destroyed, these rocks give phosphorus to terrestrial ecological systems, but part of the phosphates is involved in the water cycle and carried away to the sea. Together with the dead remains, phosphates sink to the bottom. One part of them is used, and the other part is lost in deep deposits. Thus, there is a discrepancy between the consumption of phosphorus and its return to the cycle.

As a result of the circulation of substances in the biosphere, there is a continuous biogenic migration of elements. The chemical elements necessary for the life of plants and animals pass from the environment into the body. When organisms decompose, these elements again return to the environment, from where they again enter the body.

Various organisms, including humans, take part in the biogenic migration of elements.

The role of man in the biosphere. Man - part of the biomass of the biosphere - for a long time was directly dependent on the surrounding nature. With the development of the brain, man himself becomes a powerful factor in further evolution on Earth. Man's mastery of various forms of energy - mechanical, electrical and atomic - contributed to a significant change in the earth's crust and biogenic migration of atoms. Along with the benefits, human intervention in nature often brings harm to it. Human activity often leads to a violation of natural laws. The disruption and alteration of the biosphere is a matter of serious concern. In this regard, in 1971, UNESCO (the United Nations Educational, Scientific and Cultural Organization), which includes the USSR, adopted the International Biological Program (IBP) "Man and the Biosphere", which studies the change in the biosphere and its resources under human influence.

Article 18 of the Constitution of the USSR states: “In the interests of present and future generations, the necessary measures are being taken in the USSR for the protection and scientifically based, rational use of the land and its subsoil, water resources, flora and fauna, to keep the air and water clean, to ensure the reproduction natural resources and improvement of the human environment”.

Genetic code or triplets (codons) of i-RNA corresponding to 20 amino acids (according to Bogen)

First nucleotide	Second nucleotide	Third nucleotide
		phenylalanine
				pointless	tryptophan
		histidine		glutamine (glun)
		isoleucine		methionine
		asparagine (aspn)
		aspartic acid (asp)		glutamine acid

Cytological tasks are of several types.

1. In the topic “Chemical organization of the cell”, they solve problems for building the second DNA helix; determining the percentage of each nucleotide, etc., for example, task No. 1. Nucleotides are located on the site of one DNA chain: T - C - T-A - G - T - A - A - T. Determine: 1) the structure of the second chain, 2) the percentage of content in a given segment of each nucleotide.

Solution: 1) The structure of the second chain is determined by the principle of complementarity. Answer: A - G - A - T - C - A - T - T - A.

2) There are 18 nucleotides (100%) in two strands of this DNA segment. Answer: A \u003d 7 nucleotides (38.9%) T \u003d 7 - (38.9%); G \u003d 2 - (11.1%) and C \u003d 2 - (11.1%).

II. In the topic "Metabolism and energy transformation in the cell" solve problems to determine the primary structure of the protein by the DNA code; gene structure according to the primary structure of the protein, for example, task No. 2. Determine the primary structure of the synthesized protein, if the nucleotides are located in the following sequence on the site of one DNA chain: GATACAATGGTTCGT.

1. Without violating the sequence, group the nucleotides into triplets: GAT - ACA - ATG - GTT - CGT.
2. Build a complementary strand of i-RNA: CUA - UGU - UAC - CAA - HC A.

PROBLEM SOLVING

3. According to the table of the genetic code, determine the amino acids encoded by these triplets. Answer: leu-cis-tir-glun-ala. Similar types of tasks are solved similarly on the basis of the corresponding regularities and sequences occurring in the cell of processes.

Genetic tasks are solved in the topic "Basic patterns of heredity". These are tasks for monohybrid, dihybrid crosses and other patterns of heredity, for example, task No. 3. When black rabbits were crossed, 3 black rabbits and 1 white were obtained in the offspring. Determine the genotypes of parents and offspring.

1. Guided by the law of trait splitting, designate the genes that determine the manifestation of dominant and recessive traits in this crossing. Black suit-A, white - a;
2. Determine the genotypes of the parents (giving splitting offspring in a ratio of 3:1). Answer: Ah.
3. Using the hypothesis of gamete purity and the mechanism of meiosis, write a crossover scheme and determine the genotypes of the offspring.

Answer: the genotype of the white rabbit is aa, the genotypes of black rabbits are 1 AA, 2Aa.

In the same sequence, using the appropriate patterns, other genetic problems are solved.

Photosynthesis underlies all life on our planet. This process, which takes place in land plants, algae and many types of bacteria, determines the existence of almost all life forms on Earth, converting sunlight into chemical bond energy, which is then transferred step by step to the tops of numerous food chains.

Most likely, the same process at one time initiated a sharp increase in the partial pressure of oxygen in the Earth's atmosphere and a decrease in the proportion of carbon dioxide, which ultimately led to the flourishing of numerous complexly organized organisms. And until now, according to many scientists, only photosynthesis is able to restrain the onslaught of CO 2 emitted into the air as a result of the daily burning of millions of tons of various types of hydrocarbon fuels by humans.

A new discovery by American scientists forces us to take a fresh look at the photosynthetic process

During "normal" photosynthesis, this vital gas is produced as a "by-product". In normal mode, photosynthetic "factories" are needed to bind CO 2 and produce carbohydrates, which subsequently act as an energy source in many intracellular processes. The light energy in these "factories" goes to the decomposition of water molecules, during which the electrons necessary for fixing carbon dioxide and carbohydrates are released. This decomposition also releases oxygen O 2 .

In the newly discovered process, only a small part of the electrons released during the decomposition of water is used to assimilate carbon dioxide. The lion's share of them during the reverse process goes to the formation of water molecules from "freshly released" oxygen. At the same time, the energy converted during the newly discovered photosynthetic process is not stored in the form of carbohydrates, but directly goes to vital intracellular energy consumers. However, the detailed mechanism of this process remains a mystery.

From the outside, it may seem that such a modification of the photosynthetic process is a waste of time and energy from the Sun. It is hard to believe that in living nature, where over billions of years of evolutionary trial and error, every little thing turned out to be extremely efficient, there can be a process with such a low efficiency.

Nevertheless, this option allows you to protect the complex and fragile apparatus of photosynthesis from excessive exposure to sunlight.

The fact is that the photosynthetic process in bacteria cannot simply be stopped in the absence of the necessary ingredients in the environment. As long as microorganisms are exposed to solar radiation, they are forced to convert the energy of light into the energy of chemical bonds. In the absence of the necessary components, photosynthesis can lead to the formation of free radicals that are detrimental to the entire cell, and therefore cyanobacteria simply cannot do without a backup option for converting photon energy from water to water.

This effect of reduced conversion of CO 2 to carbohydrates and reduced release of molecular oxygen has already been observed in a series of recent studies in the natural conditions of the Atlantic and Pacific Oceans. As it turned out, reduced content of nutrients and iron ions are observed in almost half of their water areas. Hence,

Roughly half of the energy of sunlight coming to the inhabitants of these waters is converted to bypass the usual mechanism of absorption of carbon dioxide and release of oxygen.

This means that the contribution of marine autotrophs to the process of CO2 uptake was previously substantially overestimated.

As Joe Bury, member of the Carnegie Institution's Department of World Ecology, the new discovery will fundamentally change our understanding of how solar energy is processed in the cells of marine microorganisms. According to him, scientists have yet to discover the mechanism of the new process, but even now its existence will force us to take a different look at modern estimates of the scale of photosynthetic absorption of CO 2 in world waters.

The oceans cover more than 70% of the Earth's surface. It contains about 1.35 billion cubic kilometers of water, which is about 97% of all water on the planet. The ocean supports all life on the planet and also makes it blue when viewed from space. Earth is the only planet in our solar system known to contain liquid water.

Although the ocean is one continuous body of water, oceanographers have divided it into four main areas: Pacific, Atlantic, Indian and Arctic. The Atlantic, Indian and Pacific oceans combine to form the icy waters around Antarctica. Some experts identify this area as the fifth ocean, most often called the South.

To understand the life of the oceans, you must first know its definition. The phrase "marine life" covers all organisms that live in salt water, which include a wide variety of plants, animals, and microorganisms such as bacteria and.

There is a huge variety of marine species that range from tiny single-celled organisms to giant blue whales. As scientists discover new species, learn more about the genetic make-up of organisms, and study fossil specimens, they are deciding how to group ocean flora and fauna. The following is a list of major phyla or taxonomic groups of living organisms in the oceans:

• (Annelida);
• (Arthropoda);
• (Chordata);
• (Cnidaria);
• Ctenophores ( Ctenophora);
• (Echinodermata);
• (Mollusca)
• (Porifera).

There are also several types of marine plants. The most common are Chlorophyta, or green algae, and Rhodophyta, or red algae.

Marine life adaptations

From the point of view of a land animal like us, the ocean can be a harsh environment. However, marine life is adapted to life in the ocean. Characteristics that allow organisms to thrive in the marine environment include the ability to regulate salt intake, oxygen-producing organs (such as fish gills), withstand increased water pressure, and adapt to lack of light. Animals and plants living in the intertidal zone deal with extreme temperatures, sunlight, wind and waves.

There are hundreds of thousands of species of marine life, from tiny zooplankton to giant whales. The classification of marine organisms is very variable. Each is adapted to its specific habitat. All oceanic organisms are forced to interact with several factors that are not a problem for life on land:

• Regulating salt intake;
• Obtaining oxygen;
• Adaptation to water pressure;
• Waves and changes in water temperature;
• Getting enough light.

Below we look at some of the ways marine life survives in this environment, which is very different from ours.

Salt regulation

Fish can drink salt water and excrete excess salt through their gills. Seabirds also drink seawater, and excess salt is expelled through "salt glands" into the nasal cavity and then shaken out by the bird. Whales do not drink salt water, but get the necessary moisture from their organisms, which they feed on.

Oxygen

Fish and other organisms that live underwater can obtain oxygen from the water either through their gills or through their skin.

Marine mammals are forced to surface to breathe, which is why whales have breathing holes on top of their heads that allow them to breathe in air from the atmosphere, keeping most of their body underwater.

Whales are able to stay underwater without breathing for an hour or more because they use their lungs very efficiently, filling up to 90% of their lungs with each breath, and also store unusually large amounts of oxygen in their blood and muscles when diving.

Temperature

Many ocean animals are cold-blooded (ectothermic) and their internal body temperature is the same as their environment. An exception are warm-blooded (endothermic) marine mammals, which must maintain a constant body temperature regardless of water temperature. They have a subcutaneous insulating layer consisting of fat and connective tissue. This layer of subcutaneous fat allows them to maintain their internal body temperature about the same as that of their terrestrial relatives, even in the cold ocean. The insulating layer of the bowhead whale can be over 50 cm thick.

water pressure

In the oceans, water pressure increases by 15 pounds per square inch every 10 meters. While some sea creatures rarely change the depth of the water, far-swimming animals such as whales, sea turtles and seals travel from shallow water to deep water in a matter of days. How do they deal with pressure?

It is believed that the sperm whale is able to dive more than 2.5 km below the ocean surface. One of the adaptations is that the lungs and chest are compressed when diving to great depths.

The leatherback sea turtle can dive to over 900 meters. Folding lungs and a flexible shell help them withstand high water pressure.

wind and waves

Intertidal animals do not need to adapt to high water pressure, but must withstand strong wind and wave pressure. Many invertebrates and plants in this area have the ability to cling to rocks or other substrates, and also have hard protective shells.

While large pelagic species such as whales and sharks are not affected by the storm, their prey can be displaced. For example, whales prey on copepods, which can be scattered over different remote areas during strong winds and waves.

sunlight

Light-demanding organisms, such as tropical coral reefs and related algae, are found in shallow, clear waters that allow sunlight to pass through easily.

Because underwater visibility and light levels can change, whales don't rely on sight to find food. Instead, they locate prey using echolocation and hearing.

In the depths of the ocean abyss, some fish have lost their eyes or pigmentation because they are simply not needed. Other organisms are bioluminescent, using luminiferous or their own light-producing organs to attract prey.

Distribution of life of the seas and oceans

From the coastline to the deepest seabed, the ocean is teeming with life. Hundreds of thousands of marine species range from microscopic algae to the blue whale that ever lived on Earth.

The ocean has five main zones of life, each with unique adaptations of organisms to its particular marine environment.

Euphotic zone

The euphotic zone is the sunlit top layer of the ocean, up to about 200 meters deep. The euphotic zone is also known as the photic zone and can be present both in lakes with seas and in the ocean.

Sunlight in the photic zone allows the process of photosynthesis to take place. is the process by which some organisms convert solar energy and carbon dioxide from the atmosphere into nutrients (proteins, fats, carbohydrates, etc.) and oxygen. In the ocean, photosynthesis is carried out by plants and algae. Seaweeds are similar to land plants: they have roots, stems, and leaves.

Phytoplankton - microscopic organisms that include plants, algae and bacteria also inhabit the euphotic zone. Billions of microorganisms form huge green or blue spots in the ocean, which are the foundation of the oceans and seas. Through photosynthesis, phytoplankton are responsible for producing almost half of the oxygen released into the Earth's atmosphere. Small animals such as krill (a type of shrimp), fish, and microorganisms called zooplankton all feed on phytoplankton. In turn, these animals are eaten by whales, large fish, seabirds, and humans.

mesopelagic zone

The next zone, extending to a depth of about 1000 meters, is called the mesopelagic zone. This zone is also known as the twilight zone, as the light within it is very dim. The lack of sunlight means that there are practically no plants in the mesopelagic zone, but large fish and whales dive there to hunt. The fish in this zone are small and luminous.

bathypelagic zone

Sometimes animals from the mesopelagic zone (such as sperm whales and squid) dive into the bathypelagic zone, which reaches a depth of about 4000 meters. The bathypelagic zone is also known as the midnight zone because light does not reach it.

Animals living in the bathypelagic zone are small, but they often have huge mouths, sharp teeth, and expanding stomachs that allow them to eat any food that falls into their mouths. Most of this food comes from the remains of plants and animals descending from the upper pelagic zones. Many bathypelagic animals do not have eyes because they are not needed in the dark. Because the pressure is so high, it's hard to find nutrients. Fish in the bathypelagic zone move slowly and have strong gills to extract oxygen from the water.

abyssopelagic zone

The water at the bottom of the ocean, in the abyssopelagic zone, is very salty and cold (2 degrees Celsius or 35 degrees Fahrenheit). At depths up to 6,000 meters, the pressure is very strong - 11,000 pounds per square inch. This makes life impossible for most animals. The fauna of this zone, in order to cope with the harsh conditions of the ecosystem, has developed bizarre adaptive features.

Many animals in this zone, including squid and fish, are bioluminescent, meaning they produce light through chemical reactions in their bodies. For example, the anglerfish has a bright protrusion located in front of its huge, toothy mouth. When the light lures small fish, the angler simply snaps its jaws to eat its prey.

Ultraabyssal

The deepest zone of the ocean, found in faults and canyons, is called the ultra-abyssal. Few organisms live here, such as isopods, a type of crustacean related to crabs and shrimps.

Such as sponges and sea cucumbers thrive in the abyssopelagic and ultraabyssal zones. Like many starfish and jellyfish, these animals depend almost entirely on the settling remains of dead plants and animals called marine detritus.

However, not all bottom dwellers depend on marine detritus. In 1977, oceanographers discovered a community of creatures on the ocean floor feeding on bacteria around openings called hydrothermal vents. These vents drain hot water enriched with minerals from the bowels of the Earth. Minerals feed unique bacteria, which in turn feed animals such as crabs, shellfish and tubeworms.

Threats to marine life

Despite the relatively small understanding of the ocean and its inhabitants, human activity has caused enormous harm to this fragile ecosystem. We constantly see on television and in the newspapers that another marine species has become endangered. The problem may seem depressing, but there is hope and many things each of us can do to save the ocean.

The threats below are not in any particular order as they are more relevant in some regions than others and some ocean dwellers face multiple threats:

• ocean acidification- if you've ever had an aquarium, you know that the correct pH of the water is an important part of keeping your fish healthy.
• Changing of the climate- We constantly hear about global warming, and for good reason - it negatively affects both marine and terrestrial life.
• Overfishing is a worldwide problem that has depleted many important commercial fish species.
• Poaching and illegal trade- Despite laws passed to protect marine life, illegal fishing continues to this day.
• Nets - Marine species from small invertebrates to large whales can become entangled and die in abandoned fishing nets.
• Garbage and pollution- various animals can become entangled in garbage, as well as in nets, and oil spills cause great damage to most marine life.
• Loss of habitat- As the world's population increases, anthropogenic pressures increase on coastlines, wetlands, kelp forests, mangroves, beaches, rocky shores and coral reefs that are home to thousands of species.
• Invasive species - species introduced into a new ecosystem can cause serious harm to native inhabitants, since due to the lack of natural predators, they can experience a population explosion.
• Marine Vessels - Ships can cause lethal injury to large marine mammals, as well as create a lot of noise, carry invasive species, destroy coral reefs with anchors, release chemicals into the ocean and atmosphere.
• Ocean noise - there are many natural noises in the ocean, which are an integral part of this ecosystem, but artificial noises can disrupt the rhythm of life for many marine life.

Oceans and seas occupy 71% (more than 360 million km2) of the Earth's surface. They contain about 1370 million km3 of water. Five huge oceans - Pacific, Atlantic, Indian, Arctic and Southern - are connected to each other through the open sea. In some parts of the Arctic and Southern Oceans, a permanently frozen continental shelf has formed, stretching from the coast (shelf ice). In slightly warmer areas, the sea freezes only in winter, forming pack ice (large floating ice fields up to 2 m thick). Some marine animals use the wind to travel across the sea. The physalia ("Portuguese boat") has a gas-filled bladder that helps to catch the wind. Yantina releases air bubbles that serve as her float raft.

The average depth of water in the oceans is 4000 m, but in some ocean basins it can reach 11 thousand m. Under the influence of wind, waves, tides and currents, the water of the oceans is in constant motion. Waves raised by the wind do not affect deep water masses. This is done by the tides, which move water at intervals corresponding to the phases of the moon. Currents carry water between oceans. As surface currents move, they slowly rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.

ocean floor:

Most of the ocean floor is a flat plain, but in some places mountains rise thousands of meters above it. Sometimes they rise above the surface of the water in the form of islands. Many of these islands are active or extinct volcanoes. Mountain ranges stretch across the central part of the bottom of a series of oceans. They are constantly growing due to the outpouring of volcanic lava. Each new flow that brings rock to the surface of underwater ridges forms the topography of the ocean floor.

The ocean floor is mostly covered with sand or silt - rivers bring them. In some places, hot springs flow there, from which sulfur and other minerals precipitate. The remains of microscopic plants and animals sink from the surface of the ocean to the bottom, forming a layer of tiny particles (organic sediment). Under the pressure of overlying water and new sedimentary layers, loose sediment slowly turns into rock.

Ocean zones:

In depth, the ocean can be divided into three zones. In the sunny surface waters above - the so-called zone of photosynthesis - most of the ocean fish swim, as well as plankton (a community of billions of microscopic creatures that live in the water column). Beneath the photosynthesis zone lie the more dimly lit twilight zone and the deep cold waters of the gloom zone. In the lower zones, there are fewer life forms - mainly carnivorous (predatory) fish live there.

In most of the ocean water, the temperature is approximately the same - about 4 ° C. When a person is immersed in depth, the pressure of water on him from above constantly increases, making it difficult to move quickly. At great depths, in addition, the temperature drops to 2 °C. There is less and less light, until finally, at a depth of 1000 m, complete darkness reigns.

Surface life:

Plant and animal plankton in the zone of photosynthesis is food for small animals, such as crustaceans, shrimps, as well as juvenile starfish, crabs and other marine life. Away from protected coastal waters, wildlife is less diverse, but there are many fish and large mammals - for example, whales, dolphins, porpoises. Some of them (baleen whales, giant sharks) feed by filtering the water and swallowing the plankton contained in it. Others (white sharks, barracudas) prey on other fish.

Life in the depths of the sea:

In the cold, dark waters of the ocean depths, hunting animals are able to detect the silhouettes of their victims in the dimmest light, barely penetrating from above. Here, many fish have silvery scales on their sides: they reflect any light and mask the shape of their owners. In some fish, flat on the sides, the silhouette is very narrow, barely noticeable. Many fish have huge mouths and can eat prey larger than themselves. Howliods and Hatchetfish swim with their large mouths open, grabbing whatever they can along the way.

The principle of the oxygen and radiocarbon method for determining primary production (photosynthesis rate). Tasks for the definition, destruction, gross and net primary production.

What are the necessary conditions on the planet Earth for the formation of the ozone layer. What UV ranges does the ozone screen block?

What forms of ecological relationships negatively affect species.

Amensalism - one population negatively affects another, but itself does not experience either negative or positive influence. A typical example is the high crowns of trees, which inhibit the growth of stunted plants and mosses, due to the partial blocking of access to sunlight.

Allelopathy is a form of antibiosis in which organisms have a mutually harmful effect on each other, due to their vital factors (for example, excretions of substances). It is found mainly in plants, mosses, fungi. At the same time, the harmful influence of one organism on another is not necessary for its life activity and does not benefit it.

Competition is a form of antibiosis in which two types of organisms are inherently biological enemies (usually due to a common food supply or limited reproduction opportunities). For example, between predators of the same species and the same population or different species that feed on the same food and live in the same territory. In this case, harm done to one organism benefits another, and vice versa.

Ozone is formed when solar ultraviolet radiation bombards oxygen molecules (O2 -> O3).

The formation of ozone from ordinary diatomic oxygen requires quite a lot of energy - almost 150 kJ per mole.

It is known that the main part of natural ozone is concentrated in the stratosphere at an altitude of 15 to 50 km above the Earth's surface.

Photolysis of molecular oxygen occurs in the stratosphere under the influence of ultraviolet radiation with a wavelength of 175-200 nm and up to 242 nm.

Ozone formation reactions:

О2 + hν → 2О.

O2 + O → O3.

Radiocarbon modification is reduced to the following. The carbon isotope 14C is introduced into the water sample in the form of sodium carbonate or bicarbonate with known radioactivity. After some exposure of the bottles, the water from them is filtered through a membrane filter and the radioactivity of plankton cells is determined on the filter.

The oxygen method for determining the primary production of water bodies (flask method) is based on determining the intensity of photosynthesis of planktonic algae in flasks installed in a reservoir at different depths, as well as in natural conditions - by the difference in the content of oxygen dissolved in water at the end of the day and at the end of the night.

Tasks for the definition, destruction, gross and net primary production.??????

The euphotic zone is the upper layer of the ocean, the illumination of which is sufficient for the process of photosynthesis to proceed. The lower boundary of the photic zone passes at a depth that reaches 1% of the light from the surface. It is in the photic zone that phytoplankton lives, as well as radiolarians, plants grow and most aquatic animals live. The closer to the Earth's poles, the smaller the photic zone. So, at the equator, where the sun's rays fall almost vertically, the depth of the zone is up to 250 m, while in Bely it does not exceed 25 m.

The efficiency of photosynthesis depends on many internal and external conditions. For individual leaves placed under special conditions, the efficiency of photosynthesis can reach 20%. However, the primary synthetic processes occurring in the leaf, or rather in the chloroplasts, and the final crop are separated by a string of physiological processes in which a significant part of the accumulated energy is lost. In addition, the efficiency of assimilation of light energy is constantly limited by the already mentioned environmental factors. Due to these limitations, even in the most perfect varieties of agricultural plants under optimal growth conditions, the efficiency of photosynthesis does not exceed 6-7%.