RESPIRATION 1 ENERGY It is important to understand that the biological meaning of ‘Respiration’ refers to a chemical process taking place in all living cells. The function of this chemical process is to make energy available for all the cell’s activities which keep it alive. ‘Breathing’, in some cases, plays a part but ‘respiration’ to a biologist does not mean the same as ‘breathing’.

THE CONCEPT OF ‘RESPIRATION’ IS CENTRAL TO ALL LIVING PROCESSES 2 THE CONCEPT OF ‘RESPIRATION’ IS CENTRAL TO ALL LIVING PROCESSES It is worth while studying this presentation thoroughly because it is essential for an understanding of all the activities of living cells and organisms

All living cells are made up of chemical substances 3 All living cells are made up of chemical substances The processes of living involve reactions between the substances A reaction is an event which produces a change in a substance For example, a reaction between carbon and oxygen (such as burning coal in air) changes the carbon in the coal, and oxygen in the air into carbon dioxide This reaction can be represented by the equation C + O2 CO2 carbon oxygen carbon dioxide

o C 4 an atom of carbon c plus a molecule of oxygen O2 combine to form a molecule of carbon dioxide CO2

5 The reaction between carbon and oxygen also releases energy in the form of heat and light (flames) Living organisms get their energy from reactions like this (but not reactions which are violent enough to produce flames) Some of the energy released in living organisms always appears in the form of heat

6 CO2 oxygen energy release source of carbon source of carbon Coal and wood are the carbon sources. The carbon dioxide goes up the chimney. oxygen source of carbon source of carbon

One of the energy-producing reactions is called respiration 7 One of the energy-producing reactions is called respiration (Respiration is not the same thing as breathing) The chemical reactions of respiration take place in all living cells The reaction takes place between oxygen and a substance which contains carbon. The reaction produces carbon dioxide and water, and releases energy The word ‘respiration’ is used in everyday language to mean breathing; as in,for example, ‘respiration rate’ (breathing rate) or ‘artificial respiration’. In biology, it is best to avoid confusion by using the term ‘respiration’ for the chemical reaction in cells. ‘Artificial respiration’, is better described as ‘resuscitation’.

The carbon-containing substances come from FOOD 8 The carbon-containing substances come from FOOD The oxygen comes from the AIR (or water) The energy is used to drive other chemical reactions taking place in cells One example of this is the release of energy in muscle cells to make them contract and produce movement Organisms living in water absorb oxygen from it. But it is not the O of H2O that they use. The oxygen which they can use is dissolved in the water and comes, originally, from the air.

9 One example of an energy-producing reaction in cells is the breakdown of sugar when it combines with oxygen This can be represented by the equation C6H12O6 + 6O2 6CO2 + 6H2O + energy sugar (glucose) oxygen carbon dioxide water This means that one molecule of sugar reacts with six molecules of oxygen to produce six molecules of carbon dioxide and six molecules of water. Energy is released during this process The carbon-containing substance in this case, is glucose (C6H12O6) but all food contains some carbon. Although the reaction is shown as if it takes place in one step, there are many more intermediate changes and the energy is released in stages, The progress of each step in controlled by chemicals called enzymes which are the subject of a separate presentation

Some examples of the use of energy in organisms 10 Some examples of the use of energy in organisms muscle contraction Respiration supplies the energy for germination chemical changes in cells cell division These are only a few examples. Every living process in living organisms needs energy from respiration

Energy use in muscle contraction 11 shoulder blade The blood stream brings food and oxygen to the muscle cells. Respiration occurs in the cells and releases energy which…… upper arm bone The drawing represents the human arm bones with two of the muscles which produce movement (biceps and triceps) lower arm bones

…….makes the muscle contract 12 …….makes the muscle contract and pull the lower arm up

food store 13 (a) (c) (b) shoot embryo shoot embryo root (a) is a section cut through the length of a maize seedling. Areas of rapid respiration are stained pink. (b) and (c) are drawings of the seed and the seedling that grows from it. Can you suggest reasons why respiration should be so rapid in the stained regions? root root

Answer The most intensely stained areas are in the root tip and the 14 Answer The most intensely stained areas are in the root tip and the shoot tip. These are regions where very rapid cell division is taking place to produce growth. Making new cells and new cytoplasm takes a great deal of energy. You might also have noticed that, in the root, there are two faint streaks of pink. These occur in the conducting tissue of the seedling. Energy is needed to transport food from the food store to the growing region.

One example of respiration in ourselves 15 One example of respiration in ourselves 2. The lungs absorb oxygen from the air 1. Air taken in 1.Food taken in 2.The stomach and intestine digest food. One of the products is glucose 3.The blood stream carries glucose and oxygen to the muscles Glucose and oxygen react to produce energy for muscle contraction 4 RESPIRATION The water produced as a waste product of respiration is picked up by the blood stream and may be lost in sweat, water vapour from the lungs or in urine 5 Carbon dioxide is carried to the lungs by the blood

Question 1 What is the most important point about respiration? 16 Question 1 What is the most important point about respiration? (a) it uses oxygen (b) It produces energy (c) It produces carbon dioxide (d) It needs food and air

17 Question 2 In which part of the human body is respiration most likely to be occurring? (a) The lungs (b) The heart (c) The muscles (d) All of these Respiration will be occurring in all parts of the human body that consists of living cells. Fingernails, toenails and hair do not contain living cells and so will not be respiring

Question 3 Which of these are waste products of respiration? 18 Question 3 Which of these are waste products of respiration? (a) Carbon dioxide (b) Water (c) Oxygen (d) Nitrogen

19 Question 4 Which of the following would be reliable indicators of respiration in a living organism? (a) Output of water vapour (H2O) (b) Output of carbon dioxide (CO2) (c) Uptake of oxygen (O2) (d) Production of energy Any wet or damp non-living material (e.g. a line full of washing) will be releasing water vapour.

Question 5 Which of the following statements are correct? 20 Question 5 Which of the following statements are correct? (a) We breathe in air (b) We breathe in oxygen (c) We breathe out air (d) We breathe out carbon dioxide Air is a mixture of nitrogen, oxygen, carbon dioxide and a small proportion of other gases. We cannot selectively breathe in only oxygen and breathe out only carbon dioxide. The lungs absorb oxygen from the air we breathe in and give out carbon dioxide. So the air we breathe out contains less oxygen and more carbon dioxide than the air we breathe in.

21 Answer Correct

22 Answer Incorrect

Anaerobic Respiration 23 Anaerobic respiration is involved at some stage in the preparation of these foodstuffs

When We Exercise… After two minutes of exercise, the body responds by supplying working muscles with oxygen. When oxygen is present, glucose can be completely broken down into carbon dioxide and water

It is also known As Fermentation Anaerobic Respiration refers to the oxidation of molecules in the absence of oxygen to produce energy It is also known As Fermentation

What happens when fermentation occurs? In Muscle Cells- During extraneous activities, the oxygen in the muscle tissue is decreased to an extent that aerobic respiration does not occur at a sufficient rate. Hence, there is a buildup of lactic acid and your muscles get tired 2. In Yeast- The fermentation end product is ethyl alcohol, and CO2

24 The process of respiration described so far has been defined as the release of energy when foodstuffs such as glucose react with oxygen to produce carbon dioxide and water. This form of respiration, which needs oxygen, is called aerobic respiration. There is another form of respiration which does not need oxygen and is called anaerobic respiration. In anaerobic respiration, glucose is still broken down to carbon dioxide with the release of energy, but without the involvement of oxygen The glucose is not completely broken down to CO2 and H2O but to CO2 and alcohol/lactic acid

Glucose Lactic acid + Energy C6H12O6 2C3H6O3 + 120 kj. 25 Anaerobic respiration can be represented by the equation C6H12O6 2C2H5OH + 2CO2 glucose alcohol energy The energy released by anaerobic respiration is considerably less than the energy from aerobic respiration. Glucose Lactic acid + Energy C6H12O6 2C3H6O3 + 120 kj.

Micro-organisms 26 Anaerobic respiration is widely used by many micro-organisms such as bacteria and yeasts. Bacteria and yeasts are microscopic single-celled organisms. Bacteria are to be found everywhere, in or on organisms, in water, air and soil Yeasts are usually found in close association with vegetable matter such as fruit

Bacteria a single bacterium 27 cell wall there are many species of bacteria and they have different shapes and sizes nucleus cytoplasm 0.002mm The vast majority of bacteria are harmless. Some are beneficial, such as those which bring about decay of dead remains. A very small proportion are harmful and cause disease in animals and plants. a single bacterium

Aerobic and anaerobic bacteria 28 Aerobic and anaerobic bacteria Bacteria which need oxygen in order to respire are called aerobic bacteria. Aerobic bacteria are likely to be found in the air, water and soil where oxygen is available Bacteria which can respire without needing oxygen are called anaerobic bacteria Some bacteria can use both aerobic or anaerobic respiration according to the availability of oxygen, There are some anaerobic bacteria which cannot survive in the presence of oxygen. Anaerobic bacteria are to be found in situations where oxygen is lacking, such as in stagnant water, waterlogged soils or the intestines of animals

30 Fermentation One form of anaerobic respiration in bacteria and yeasts is called fermentation. During fermentation, sugar is broken down to alcohol and carbon dioxide The reaction described in slide 25 is an example of fermentation Fermentation is involved in brewing and wine-making

Yeasts 29 cell wall nucleus cytoplasm 0.005mm vacuole Yeast cells dividing 0.005mm vacuole Yeasts can be seen as a thin, greyish ‘bloom’ on the surface of grapes, but they are present on the surface of most fruits. When these fruits are crushed and mixed with water, the anaerobic respiration of the yeasts causes fermentation with the production of carbon dioxide and alcohol. single yeast cell

31 Wine making Grapes are crushed and the sugar they contain is fermented by yeasts to produce alcohol and carbon dioxide. The carbon dioxide usually escapes but if the wine is bottled before fermentation is complete, the carbon dioxide dissolves and escapes as bubble when the bottle is opened This is the case with ‘sparkling’ wines such as Champagne Different varieties of grape produce different types of wine

Black grapes growing in a vineyard 32 Black grapes growing in a vineyard © Ilan’s Wine Making

33 Brewing In brewing beer, a sugary product (malt) is dissolved out of germinating barley Yeast is added to this solution and fermentation begins, producing alcohol and carbon dioxide Some of the carbon dioxide escapes but the rest dissolves in the beer when it is bottled or put into casks When the bottles or casks are opened, the dissolved CO2 escapes as bubbles

Beer fermenting 34 ©Stuart Boreham/CEPHAS The carbon dioxide bubbles plus some of the beer constituents produce a dense froth on top of the beer. The fermentation vessel is an old-fashioned open type. ©Stuart Boreham/CEPHAS

Baking 35 In baking, yeast is added to a mixture of flour and water, made into the form of a dough The yeast first changes the flour starch into sugar and then ferments the sugar into alcohol and CO2 The CO2 forms bubbles in the dough which cause it to expand (‘rise’) When the dough is baked, the heat evaporates the alcohol but makes the trapped bubbles expand giving the bread a ‘light’ texture

Dough rising 36 The yeast is mixed with the dough After 1 hour in a warm place the dough has risen as a result of the carbon dioxide produced by the yeast

37 The ‘holes’ in the bread are made by the carbon dioxide bubbles. This gives the bread a ‘light’ texture

Question 1 Which statements are correct ? 38 Which statements are correct ? Anaerobic respiration is different from aerobic respiration because a it produces CO2 b it does not need glucose c it does not need oxygen d it produces less energy

Question 2 In what circumstances do our muscle use anaerobic 39 In what circumstances do our muscle use anaerobic respiration ? a When insufficient glucose reaches the muscles b When the carbon dioxide level increases c When insufficient oxygen reaches the d When we are asleep

Question 3 Anaerobic bacteria are most likely to be found 40 Question 3 Anaerobic bacteria are most likely to be found a in the middle of a compost heap b in the air c in fast-flowing streams d on the surface of the skin

Question 4 In which of the following is the production of CO2 41 Question 4 In which of the following is the production of CO2 more important than the production of alcohol ? a Brewing beer b Fermenting grape juice c Making bread d Bottling wine

42 Answer Incorrect

43 Answer Correct