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Пособие.Увлекательный мир биологии.doc
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Respiration in all living things

So far, we have only considered respiration in air. This kind of respiration is called aerobic respiration. However, respiration is also possible when there is no air and no oxygen. This is called anaerobic respiration. Anaerobic respiration can occur in animals and plants.

The most important application of anaerobic respiration is fermentation. Fermentation is used to make beer and wines. It involves the use of yeast. Yeast contains tiny single-celled organisms which can respire aerobically like animals and plants. When yeast is mixed with a solution of sugar or glucose, it quickly starts to respire. The yeast uses sugar and oxygen dissolved in the solution to produce carbon dioxide, water and energy. This, of course, is aerobic respiration.

sugar (glucose)

oxygen

carbon dioxide

water

energy

C6H12O6

+

6O2

6CO2

+

6H2O

+

2900 (kJ).

However, when all the available oxygen has been used, the yeast goes on respiring. Under these anaerobic conditions, the yeast uses up more glucose, but instead of producing carbon dioxide and water, the products are carbon dioxide and ethanol.

sugar (glucose)

carbon dioxide

+

ethanol

+

energy

C6H12O6

2CO2

+

2C2H5OH

+

84 kJ.

Although anaerobic respiration allows the yeast to survive without oxygen, it is very inefficient. Notice in the equations above that one formula mass of glucose produces 2900 kJ of energy in aerobic respiration, but only 84 kJ in anaerobic respiration. Under anaerobic conditions, most of the energy that the yeast could get from glucose remains "locked up" in the ethanol.

The common name for ethanol is alcohol, so this example of anaerobic respiration is sometimes called alcoholic fermentation.

Exercises

1. Answer the questions:

  1. What types of respiration are mentioned in the text?

  2. How is respiration carried on in human beings?

  3. What system controls the process and the rate at which respiration proceeds?

  4. What organs are involved in respiration?

  5. Where is oxygen combined with hemoglobin?

  6. What air does inhaling draw into the lungs?

  7. What are changes in the size and gross capacity of the chest controlled by?

  8. Why does mucus play an important role in breathing?

  9. What prevents the trachea and bronchi collapsing?

  10. Why is food often called biological fuels?

2. What do these words mean? Explain them in English.

respiration

gaseous exchange

breathing

cellular respiration

nasal cavity

external respiration

cilia

internal respiration

mucus

anaerobic respiration

larynx

bronchial tree

alveoli

3. Prove that:

  1. Humans use both external and internal respiration.

  2. Gas exchange in the lungs is a reversed process.

  3. Cellular respiration refers to the chemical reactions.

  4. Some animals can respire anaerobically.

4. Using the information received from the text, describe the following:

  • organs, taking part in gaseous exchange;

  • the structure of the bronchial tree;

  • the process of respiration in human beings.

5. Render the text into English.

Система органов дыхания обеспечивает доставку кислорода из внешней среды к крови и выведение из организма углекислого газа. К ней принадлежат носовая полость, глотка, гортань, трахея и легкие. В функциональном отношении органы дыхания подразделяются на дыхательные пути, по которым воздух поступает в легкие и выводится из последних в окружающую среду, и дыхательную часть, в которой непосредственно происходит газообмен между кровью и воздухом.