Physics and birds. Why can birds fly to great heights with impunity? The progress of work when filling out the scheme
Lesson on the topic
"The reason and significance of warm-blooded birds"
When studying the topic “Bird Class”, the guys for the first time get acquainted with such an important concept as warm-bloodedness. It is very important that students understand that the maintenance of a constant body temperature is ensured by the interaction of a number of physiological systems of the body. A good knowledge of this material is necessary to explain complex evolutionary and ecological problems.
Teacher.
- Guys, why are there fewer birds in the forest in winter than in summer?
(Suggested answers: little or no food(for insectivorous birds), a lot of snow, cold.)
- Can a feather cover protect birds from frost in winter? ( Maybe, but only partially.)
The main questions that we must answer during today's lesson are: what warms the bird's body? How do they maintain a constant temperature? Where does the energy for flight come from?
How is heat generated in general? ( Suggested answers: in the combustion of organic matter, which occurs in the presence of oxygen.)
- What drives the car? What makes organisms move? ( Due to the energy generated during combustion(oxidation)organic matter with the participation of oxygen.)
How much energy do birds need? After all, they can fly long distances, develop high speed. (Working with tables.)
Table 1. Distances traveled during flights
Table 2. Surface area of the wings and the load on them
For comparison, the glider model has a wing load of 2.5 kg / m 2.
Table 3. Wing beat frequency
Table 4. Maximum flight speed
The smaller the bird, the more food for every gram of body weight it needs. As the size of the animal decreases, its mass decreases faster than the surface area of the body through which heat is lost. Therefore, small animals lose more heat than large ones. Small birds eat an amount of food per day equal to 20–30% of their own weight, large birds - 2–5%. A titmouse can eat as many insects in a day as it weighs itself, and a tiny hummingbird can drink an amount of nectar that is 4-6 times its own weight.
Repeating the stages of splitting food and the features of the respiratory system of birds, we fill in the scheme No. 1 in stages.
The progress of work when filling out the scheme
Intense motor activity of birds requires a lot of energy. In this regard, their digestive system has a number of features aimed at the efficient processing of food. The beak serves as an organ for capturing and holding food. The esophagus is long, in most birds it has a pocket-like extension - goiter, where food softens under the influence of goiter fluid. The glandular stomach has glands in its wall that secrete gastric juice.
The muscular stomach is equipped with strong muscles and is lined from the inside with a strong cuticle. In it, mechanical grinding of food takes place. Digestive glands (liver, pancreas) actively secrete digestive enzymes into the intestinal cavity. The split nutrients are absorbed into the blood and carried to all cells of the bird's body.
How long does it take for birds to digest food? Small owls (house owls) digest a mouse in 4 hours, a gray shrike - in 3 hours. Juicy berries in passerines pass through the intestines in 8–10 minutes. Insectivorous birds fill their stomach 5-6 times a day, granivorous birds - three times.
However, in itself, the absorption of food and the entry of nutrients into the blood is not the release of energy. Nutrients need to be "burned" in tissue cells. What system is involved in this? ( Lightweight, air sacs.)
Muscles must be well supplied with oxygen. However, birds cannot ensure the delivery of the required amount of oxygen due to the large amount of blood. Why? ( An increase in the amount of blood would increase the mass of the bird and make it difficult to fly.)
An intensive supply of oxygen to tissue cells in birds occurs due to "double breathing": oxygen-rich air passes through the lungs both during inhalation and exhalation, and in the same direction. This is provided by a system of air sacs penetrating the bird's body.
In order for the blood to move faster, you need high blood pressure. Indeed, birds are hypertensive. In order to create high blood pressure, the heart of birds must contract with great force and high frequency (Table 5).
Table 5. Heart weight and heart rate
As a result of the oxidation (combustion) of nutrients, energy is generated. What is she spending on? (We are finishing filling out scheme No. 1).
Output.
An active oxidative process helps maintain a constant body temperature.
High body temperature provides a high metabolic rate, rapid contraction of the heart muscle and skeletal muscles, which is necessary for flight. High body temperature allows birds to shorten the period of development of the embryo in the hatching egg. After all, incubation is an important and dangerous period in the life of birds.
But constant body temperature has its drawbacks. Which? We fill out the scheme number 2.
So, maintaining a constantly high body temperature is beneficial for the body. But for this it is necessary to consume a lot of food, which must be obtained somewhere. Birds had to develop various adaptations and behaviors to get enough food. Here are some examples.
Next, students make reports on the topic “How different birds get their own food” (their preparation could be homework for this lesson).
Fishing Pelicans
Pelicans sometimes fish together. They will find a shallow bay, cordon it off in a semicircle and begin to flap the water with their wings and beaks, gradually narrowing the arc and approaching the shore. And only after driving the fish to the shore, they start fishing.
Owl hunting
Owls are known to hunt at night. The eyes of these birds are huge, with a greatly expanding pupil. Through such a pupil and with poor lighting, enough light enters. However, it is impossible to see prey - various small rodents, mice and voles - from afar in the dark. Therefore, the owl flies low above the ground and looks not to the sides, but straight down. But if you fly low, the rustling of the wings will scare away the prey! Therefore, the owl has soft and loose plumage, which makes its flight completely silent. However, the main means of orientation in nocturnal owls is not sight, but hearing. With its help, the owl learns about the presence of rodents by squeaking and rustling and accurately determines the location of the prey.
Armed with stone
In Africa, in the Serengeti reserve, biologists have observed how vultures got their food. This time the food was ostrich eggs. To get to the delicacy, the bird took a stone with its beak and threw it with force at the egg. The strong shell, which could withstand the blows of the beak of even such large birds as vultures, cracked from the stone, and one could feast on the egg.
True, the vulture was immediately pushed back from the feast by vultures, and he was taken for a new egg. This most interesting behavior was then repeatedly noted in the experiment. Eggs were tossed to the vultures and expected to happen. Noticing the delicacy, the bird immediately picked up a suitable stone, sometimes weighing up to 300 g. The vulture dragged it in its beak for tens of meters and threw it at the egg until it cracked.
Once a vulture was given fake chicken eggs. He took one of them and started throwing it on the ground. Then he took the egg to a large rock and threw it against it! When this did not bring the desired result, the vulture began to desperately beat one egg against another.
Numerous observations have shown that the birds tried to split any egg-shaped object with stones, even if it was huge or painted in unusual colors - green or red. But they did not pay attention to the white cube at all. Scientists have found, in addition, that young vultures do not know how to break eggs and learn this from older birds.
osprey fisherman
The osprey is an excellent angler. Seeing the fish, it quickly rushes into the water and plunges its long sharp claws into the body of the victim. And no matter how the fish tries to escape from the claws of the predator, it almost never succeeds. Some observers note that the bird holds the caught fish with its head in the direction of flight. Perhaps this is an accident, but it is more likely that the osprey is trying to catch fish in such a way that later it would be easier to carry it. Indeed, in this case, air resistance is less.
Conclusion from student reports
- the progressive development of the brain and the leading sense organs (vision, hearing) is associated with an intensive metabolism, high mobility and complex relationships with environmental conditions. 
Now explain why birds have become widespread in all climatic zones. What is bird flight? ( Warm-bloodedness allows birds not to be afraid of frost, to remain active even at very low ambient temperatures. However, the lack of food in winter forces them to migrate to more nutritious places.)
2. Water heating pipes passing through the basement are wrapped with asbestos, felt, or a gutter with sawdust is also placed. Why do they do it?
3. Explain the reason that in the cold, metal objects seem colder than wooden ones. At what temperature will both metal and wood appear to be equally hot?
4. a) Why does soil covered with snow freeze less than open soil? b) Which soil warms up faster in the sun - wet or dry?
5. a) Why do potatoes buried in a pit for the winter not freeze? b) What harms plants, especially cereals - heavy snow or snowless winter?
6. You were going to have breakfast and poured coffee into a glass. But you are asked to leave for a few minutes. To keep coffee hot, do you need to pour milk into it before leaving or upon returning?
7. For what purpose are raspberry bushes in the northern regions bent to the ground for the winter?
8. Why do they prefer to use a wooden spoon when cooking jam?
9. What protects from the cold better - a wooden wall or a layer of snow of the same thickness?
10. (a) Why can ducks and other waterfowl stay in cold water for long periods of time without getting supercooled? b) Explain the purpose of a thick layer of subcutaneous fat in whales, seals and other animals living in the waters of the polar seas, c) Why do animals living in cold countries have a thicker hairline than animals living in hot countries?
11. How can one explain that some species of birds (black grouse, capercaillie, partridge, etc.) burrow into snowdrifts and sometimes spend several days there?
12. In refrigerators, the air is cooled by a special compound flowing through pipes. Why are these pipes (evaporator) placed at the top of the refrigerator?
13. Why are water or steam heating radiators most often located in the lower part of the room?
14. Air is heated in test tubes and water is boiled. Why does the hand not feel the heat?
15. In cold rooms, our feet get cold first of all. How can this be explained?
16. In the poem "Caucasus" by A. S. Pushkin there are these words: "The eagle, having risen from a distant peak, soars motionless on a par with me." Explain why eagles, hawks, kites, and other large birds soaring high in the sky can stay at the same height without flapping their wings.
17. There is a case when a skydiver with an open parachute, instead of going down, began to go up. How could this happen?
18. Plants in low places are most often exposed to frost. How can this be explained?
19. Why is the flight on an airplane calmer in the morning and at night - less chatting and motion sickness?
20. If on a sunny spring day we go out into the field and look along the surface of a plowed piece of land, then all the objects behind it seem to us to oscillate. Why?
21. Explain how the air in the room is cooled in winter when the window is open.
22. In which case will a pot of hot water cool faster - when the pot is placed on ice or when ice is placed on the lid of the pot?
23. Which parts of the earth's surface heat up more in sunny weather - a plowed field or a green meadow; dry or wet soil? Why?
24. If a clear night is expected in spring or autumn, gardeners make fires so that the smoke envelops the plants. What for?
25. Why is frost stronger on clear winter nights than cloudy weather?
26. Why in the practice of agriculture, moisture-intensive clay soils are considered cold, and low- moisture-intensive sandy soils are considered warm?
27. Why is it difficult to remove heat from heated objects on artificial Earth satellites?
1. Indicate the main similarities and differences between birds and reptiles.
Similarities: dry skin without glands, internal fertilization, oviposition, chest
Differences: birds have a four-chambered heart and, accordingly, are warm-blooded, air sacs, feather cover, development of the cerebellum and cerebral cortex, changes in the skeleton due to flight (hollow bones, wings, etc.), feather cover
2. Name the main adaptations of birds for flight in the structure: integument, skeleton, internal organs.
Feathers - form a streamlined body shape, plus they create a fly surface of the wing, they also serve for turns;
. the bones of birds are light, as they have air chambers;
. a minimum of organs, which also facilitates the overall weight of the body.
3. Explain why birds are warm-blooded animals. What is the significance of warm-bloodedness in the life of birds?
Birds are warm-blooded animals because they have a high and constant body temperature due to intensive metabolism. Due to this, the birds are active all year round.
4. What differences in the structure of internal organs and the behavior of birds characterize their complication in comparison with reptiles?
- birds, unlike reptiles, are warm-blooded, have a four-chambered heart (the left side is arterial blood, the right side is venous; complete separation)
- care of offspring
- Birds do not have a bladder or teeth
- birds have double breathing (lung sacs formed by outgrowths of the bronchi + lungs)
- birds have a well developed cerebellum
- birds are covered with feathers, have the ability to fly, in connection with this - hollow bones, outgrowth of the sternum - keel
- two-chamber stomach (glandular and muscular), goiter
- reproductive system - females have only one, the left ovary
5. Tell us about the structure of the bird's egg and the significance of its parts in the development of the embryo.
The structure of a bird's egg: germinal disc, air chamber, protein, yolk, shell, cords, shell membrane.
The meaning of its parts: the natural antibiotic of enzymatic origin, lysozyme, contained in the protein, is of great importance. It protects the spoilage of the protein, and, consequently, the eggs from the activity of microorganisms. Under the shell there is a two-layer shell membrane, which is also gas and moisture permeable, but does not allow colloids to pass through, that is, it retains the egg white and prevents it from leaking out. This shell plays a protective role. The air chamber of the egg plays an important role, ensuring the gas exchange of the embryo during the transition to pulmonary respiration, that is, before the shell is pecked. Therefore, if the air chamber is displaced relative to the blunt end, then the young animals die during the transition to pulmonary respiration.
6. What is the difference between seasonal phenomena in the life of birds and reptiles?
Birds fly away to other places (warmer), and reptiles either hide or hibernate.
7. List the most common birds in your area. What role do they play in nature?
Pigeons, crows, sparrows are common in cities. They play an extremely important role by eating many insects, regulating their numbers in natural communities. Insectivorous birds render a great service to man, destroying pests in gardens, squares and parks.
8. Using the example of chickens, explain the changes in birds during domestication.
Domestication of birds occurred in ancient times. The ancestor of all modern breeds of domestic chickens was the banking, or bush, chicken, common in the forests of Southeast Asia. Domestication took place in India several millennia BC. Chickens were brought to Europe in ancient times. Chickens are bred for meat, eggs and feathers. There are fighting cocks and ornamental hens. In the process of domestication, the productivity of chickens has increased significantly. If wild banking chickens lay 12-15 eggs per year, then modern egg-bearing breeds - 200-300 eggs, and at the same time they lay almost daily. Such are the leggorn breeds bred in many European countries and the USA, and Russian whites bred from them. Leggorns have lost their instinct to brood. Common breeds have been bred, from which both meat and eggs are obtained.
Which statements are true?
1) Dry skin, absence of glands on the body, many horn formations in birds indicate their origin from reptiles.
2) The strength of the skeleton of birds is given by a fixed connection, the fusion of many bones.
9) In the incubator, the development of the chicken embryo in the egg occurs at a temperature of +37 ... +39 "C and at a certain humidity.
10) The annual life cycle of migratory birds consists of the following stages: spring migration, nesting, molting, autumn migration, wintering.
In good weather, sometimes it happens to see large birds at great heights.
Eagles, reaching almost a sazhen in a wingspan, can rise to such a height, from where to a person standing on the ground they seem to be a barely noticeable black dot drawn against the light background of the sky. This height is so significant that, due to the rarefied atmosphere, no mammal could live there. To this it must be added that birds very quickly rise to such a height and can descend even faster; therefore, they can quickly move from a region of high pressure to a region of low pressure and vice versa. We have in the Crimea huge birds of prey that feed on carrion and are called vultures. They just love to climb to great heights. Distinguished by extremely sharp eyesight, they examine the earth from there. Noticing the corpse of a horse or cow, from a great height they descend on carrion for no more than two or three minutes. Therefore, in such a short time they pass from an extremely rarefied atmosphere into the region of ordinary pressure. At the same time, no violations in the administration of their body are found. Such trips pass for them with impunity.
This ability to endure rapid and large changes in atmospheric pressure is explained by the special structure of the bird's body. This body, one might say, is permeated with air sacs that are in communication with the lungs, and the lungs are in communication with the external environment or air. If you have any killed wild bird or even a pigeon in your kitchen, try to make a little experiment on it. Break her leg at the very paw and insert the break into the water. Then cut the windpipe, insert a tube into it, press the walls of the throat against the walls of the tube more tightly and start blowing into the tube. Then air bubbles will come out of the fracture of the leg bone. This indicates that the bone voids are in communication with the lungs. In general, the bones of birds do not contain bone marrow inside themselves, as in mammals. These bones are pneumatic, that is, they are filled with air, and this air can freely circulate through the bones, go out into the lungs, and from there out. The lungs of birds are small, but they are equipped with large air sacs that fit under the skin, between the muscles, the viscera, and sprout into the voids of the bones. These bags have extremely thin walls, so that it is impossible to dissect them and remove them from the bird. But it is not difficult to prove their presence. If a dead bird is blown into the windpipe, then its body swells, and the skin rises. This is due to the fact that the subcutaneous sacs swell. If the body of a freshly killed bird is crushed, then a slight crackling is heard, which occurs due to the fact that the air sacs burst. After such an operation, the bird seems smaller than before the operation.
Now, if we imagine that the bird is ascending, where the pressure becomes less and less, then the pressure in the air inside the body of the bird also decreases accordingly. This means that the pressure from the outside will be equal to the pressure from the inside, as a result of which the bird does not undergo any violations in the administration of its organs.
GROUP #1
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"Lesson-quintet on the topic: Thermal phenomena."
Lesson - quintet on the topic "Thermal phenomena"
Subject: Physics
Class: 8
Teacher: Nikiforova Natalya Vladilenovna
Lesson type: Lesson of generalization, consolidation of knowledge and skills.
Duration: 40 min
Textbook: A. V. PERYSHKIN. Physics, 8th grade. Moscow: Bustard, 2010
Lesson Objectives:
broaden the horizons of students
learn to apply knowledge in a new situation,
educate students' communication skills.
Terms of the game: the class is divided into 5 groups of 5-6 people. Each group receives 5-6 questions (Appendix No. 1). Groups choose captains, discuss questions for 5-7 minutes, distribute questions. Each student must answer at least one question, but the answers are discussed all together.
If the guys quickly answered all their questions, they can discuss the tasks for another group, so that later they can complete the answers and thereby earn additional points for their group. For correct answers and additions, students receive tokens, so the spirit of competition appears (square - complete answer - 1 point, triangle - incomplete answer - 0.5 points). The number of points earned is entered by the captain in the table - statement (Appendix No. 2). The captain evaluates the performance of each member of the group.
Application No. 1
GROUP #1
1. Half of the icy surface of the pond has been covered with a thick layer of snow since the beginning of winter, and the other half has been cleared for skating. On which side is the ice thickest?
2. Explain why birds with large wings (eagles, kites) can stay at the same height without flapping their wings.
3. If in May or September it was clear during the day, and in the evening the sky was overcast, should we expect frost at night?
4. Why is it easier to remove a ground glass stopper from a vial if you rub its neck with a dry cloth or paper?
5. Why is the low specific heat of mercury compared to the specific heat of other liquids one of the advantages of mercury for its use in thermometers?
6. Why is the specific heat of combustion of raw firewood less than the specific heat of combustion of dry firewood of the same breed?
GROUP #2
1. Famous for their high quality, Russian (Orenburg) shawls are knitted from yarn made from the finest fibers of goat down. Why is such a scarf particularly good at protecting against the cold?
2. Why do fishermen working on sailboats prefer to go to sea at night and return from fishing during the day?
3. The earth's atmosphere, due to its transparency, absorbs very little sunlight and therefore does not heat up. Why is it hot in summer even in the shade?
4. Why are car tires made of rubber, which does not soften and does not lose strength even at 100°C and above?
5. Why do iron stoves heat up a room faster than brick stoves, but do not stay warm for so long?
6. Why is it unprofitable to use gunpowder as fuel, and why can't gunpowder be replaced by gasoline in artillery pieces?
GROUP #3
1. Why are raspberry bushes in the northern regions bent to the ground for the winter?
2. Why are light objects - fluffs, scraps of paper, cotton wool, etc. – are drawn into the opening of the stove when it is heated?
3. At what time of the year and for what purpose are fires lit in orchards?
4. Prove that wind turbines run on solar energy.
5. If you dip one hand into cold water and the other into warm water, and then, taking them out, lower both into water that has a moderate temperature, then the hand that was in cold water will feel warm, and the one that was in warm water will feel cold. How to explain it?
6. Hot coal, placed on a metal plate, goes out quickly, but continues to smolder on a wooden board. Why?
GROUP #4
1. For what purpose is the face sometimes smeared with a greasy cream in winter in a big frost?
2. There is a known case when a skydiver with an open parachute, instead of going down, went up. How could this happen?
3. Why do cities in which the air is polluted with dust and smoke receive less solar energy?
4. Why is the temperature of the water in the reservoirs lower than the temperature of the sand on the shore on a summer day? And what happens at night?
5. Why does the water in the sea become warmer after a strong storm?
6. Why is it possible to light a wooden torch with a single match, but not a large log?
GROUP #5
1. In severe frost, birds often freeze on the fly than sitting still. How can this be explained?
2. Why is the flight on an airplane calmer in the morning and at night - less chatting and motion sickness?
3. Why is the highest air temperature not at noon, but in the afternoon?
4. Why sometimes the lid of a kettle in which water boils bounces, and sometimes not?
5. There are three medical thermometers. Two of them were not shaken and show 37 and 39°C. The third one was shaken so that all the mercury from the tube was removed into the expanded part of it. What will thermometers show if they are lowered for 5-10 minutes into a vessel with water at a temperature of 38 ° C?
6. Why do we blow strongly on the flame of a match, candle, etc. when we want to extinguish it?
Application No. 2
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| Group work as a whole | |||