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© Boardworks Ltd 2004 1 of 36 KS4 Biology Respiration.

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1 © Boardworks Ltd of 36 KS4 Biology Respiration

2 © Boardworks Ltd of 36 Contents Respiration Anaerobic respiration Summary activities Releasing energy Rate of respiration Aerobic respiration

3 © Boardworks Ltd of 36 Energy for life Every living cell in your body needs energy. The average adult has about 50 million million cells – that’s a lot of energy! In body cells, the energy needed for life comes from the chemical energy stored in glucose. energy Where does all this energy come from?

4 © Boardworks Ltd of 36 What is needed for releasing energy? What other substance is needed for energy to be released from this fuel? Burning is a chemical reaction in which energy is released in the form of heat. ? fuel oxygen

5 © Boardworks Ltd of 36 What does the body need for releasing energy? The body’s energy-releasing process depends on the digestive system and the breathing system. How does the body’s energy-releasing process compare with releasing energy from wood? What are the substances supplied by these systems? ? ? glucose is the fuel supplied by the digestive systemoxygen is supplied by the breathing system

6 © Boardworks Ltd of 36 Glucose and oxygen enter the body in different ways, Where are these substances needed and how do they get there? Glucose and oxygen are transported around the body by the circulatory system. Blood flowing in blood vessels takes these important substances to where they are needed – the body’s cells. Transport around the body but are needed at the same destinations.

7 © Boardworks Ltd of 36 In the body’s cells, the chemical energy stored in glucose is usually released by a chemical reaction with oxygen. The body’s energy-releasing process What is this energy-releasing process called? glucose oxygen energy respiration Why does every living cell need a constant supply of glucose and oxygen?

8 © Boardworks Ltd of 36 Contents Respiration Anaerobic respiration Summary activities Releasing energy Rate of respiration Aerobic respiration

9 © Boardworks Ltd of 36 Respiration is the process used by the body’s cells to release the chemical energy stored in glucose. When oxygen is involved in this energy-releasing process, it is called aerobic respiration. What do you think aerobic means? Aerobic respiration is an efficient process that generates enough energy to supply the whole body. Our bodies perform aerobic respiration most of the time, as long as the supply of oxygen remains high enough. What is aerobic respiration? aerobic = ‘with oxygen’

10 © Boardworks Ltd of 36 Waste products of aerobic respiration Breathing in obtains the oxygen needed for aerobic respiration. How does the body get rid of the waste products? Breathing out removes the waste products of aerobic respiration. How can the waste products of this reaction be identified? Aerobic respiration releases energy that is useful. This process is a chemical reaction between glucose and oxygen which also generates waste products. ? glucose oxygen ? energy

11 © Boardworks Ltd of 36 Waste products – limewater test Limewater turns cloudy when carbon dioxide passes through. What does this test tell you about aerobic respiration? One waste product of aerobic respiration must be… 2. Blow gently through a straw into the limewater. 3. After a short time, the limewater turns cloudy. limewater straw 1. Take a test tube of limewater, a clear liquid. …carbon dioxide.

12 © Boardworks Ltd of 36 Waste products – see your breath test Water vapour condenses into a liquid and becomes visible. What does this test tell you about aerobic respiration? Another waste product of aerobic respiration must be… What happens when you breathe out onto a cold pane of glass? What happens when you breathe out on a freezing cold day? In both cases, you can see some of the air that you have breathed out. Why? water vapour …water.

13 © Boardworks Ltd of 36 Aerobic respiration: summary Summarize the process of aerobic respiration in a sentence. Aerobic respiration is a chemical reaction so it can also be summarized in a word equation. What is the word equation for this vital chemical reaction? Aerobic respiration is a chemical reaction that takes place in all living cells, in which glucose reacts with oxygen to produce carbon dioxide and water and stored chemical energy is released.

14 © Boardworks Ltd of 36 Aerobic respiration: word equation carbon dioxide glucose oxygen water carbon dioxide water oxygen glucose energy

15 © Boardworks Ltd of 36 Aerobic respiration: word equation activity

16 © Boardworks Ltd of 36 Aerobic respiration: quiz

17 © Boardworks Ltd of 36 Contents Respiration Anaerobic respiration Summary activities Releasing energy Rate of respiration Aerobic respiration

18 © Boardworks Ltd of 36 The rate of respiration Aerobic respiration is a chemical reaction and so has a rate. Is the rate of this reaction always the same? Your body requires different amounts of energy depending on how active you are. So the rate of aerobic respiration changes depending on the amount of energy needed. During what type of activities, does the rate of aerobic respiration increase so that more energy can be released? carbon dioxide glucose oxygen water energy

19 © Boardworks Ltd of 36 When does the body need to release more energy? How much energy is needed? During which type of activities is the rate of aerobic respiration higher? not very active = low energy requirements very active = high energy requirements

20 © Boardworks Ltd of 36 Different energy needs How does the body respond to these different rates of aerobic respiration? high energy need These extremely different activities both need energy from aerobic respiration but is the rate of this reaction the same? low energy need = low rate of aerobic respiration = high rate of aerobic respiration

21 © Boardworks Ltd of 36 The body’s response to low energy needs During sleep, the body’s energy needs are low and so the rate of aerobic respiration is slow but steady. How does this affect the amount of glucose and oxygen needed? How does this affect the heart rate and breathing rate? Under these resting conditions, the body has plenty of time to inhale oxygen and the blood is able to supply enough low energy need low rate of aerobic respiration low demand for glucose and oxygen slow heart and breathing rates glucose and oxygen to the body’s cells.

22 © Boardworks Ltd of 36 The body’s response to high energy needs During running, the body’s energy needs are high and so the rate of respiration increases to meet this demand. How does this affect the amount of glucose and oxygen needed? How does this affect the heart rate and breathing rate? high energy need high rate of aerobic respiration high demand for glucose and oxygen fast heart and breathing rates Under these tougher conditions, the body has to work hard to supply enough glucose and oxygen to the body’s cells for aerobic respiration to produce enough energy.

23 © Boardworks Ltd of 36 Contents Respiration Anaerobic respiration Summary activities Releasing energy Rate of respiration Aerobic respiration

24 © Boardworks Ltd of 36 Not enough oxygen! Most of the time the body’s cells has a good supply of oxygen and is able to release energy by aerobic respiration. carbon dioxide glucose oxygen water energy Sometimes, during strenuous exercise, the breathing rate and blood flow are not able to deliver enough oxygen to the body’s cells. How does this affect the release of energy?

25 © Boardworks Ltd of 36 Not enough oxygen! If the body is not able to supply enough oxygen, aerobic respiration cannot take place and energy is not released! carbon dioxide glucose oxygen water energy The body still has a supply of glucose, so how does it continue to get energy? When there is not enough oxygen, energy can still be released from glucose by another type of respiration called anaerobic respiration.

26 © Boardworks Ltd of 36 Respiration without oxygen During anaerobic respiration, glucose breaks down into a substance called lactic acid and some energy is released. What do you think anaerobic means? lactic acid energy glucose Our bodies can only release energy without oxygen for a short period of time. anaerobic = ‘without oxygen’ Anaerobic respiration involves the incomplete breakdown of glucose and so releases less energy than aerobic respiration.

27 © Boardworks Ltd of 36 Anaerobic respiration: word equation lactic acid glucose lactic acid glucose energy

28 © Boardworks Ltd of 36 The problems with anaerobic respiration Anaerobic respiration is useful to the body when energy is needed in a hurry. There are two problems with anaerobic respiration: Anaerobic respiration releases much less energy from glucose compared to aerobic respiration. Lactic acid is a poisonous waste product. Why is anaerobic respiration not the best way to get energy from glucose? lactic acid glucose energy

29 © Boardworks Ltd of 36 Why is lactic acid so harmful? Lactic acid is the product of anaerobic respiration and is harmful because it can stop muscles from doing their job. If lactic acid builds up in muscle cells, it stops muscles from contracting and relaxing and they become fatigued. The muscles ache and the body experiences cramp, which forces the body to stop what it is doing and rest. Why can anaerobic respiration only be carried out for short periods of time?

30 © Boardworks Ltd of 36 Recovery and getting rid of lactic acid After anaerobic respiration, the body is in recovery and must get rid lactic acid. The body is now at rest but the breathing rate and heart rate remain high. Why does this happen? carbon dioxide lactic acid oxygen water Why do the breathing and heart rates return to normal after a few minutes of recovery? lactic acid energy glucose Oxygen is needed to get rid of lactic acid by turning it into carbon dioxide and water.

31 © Boardworks Ltd of 36 Oxygen debt – build up During aerobic respiration, muscles get energy from glucose by ‘paying’ for it with oxygen. During anaerobic respiration, muscles get energy from glucose but do not ‘pay’ for it with oxygen. carbon dioxide glucose oxygen water energy lactic acid glucose energy When and how is this oxygen debt ‘paid off’? This means that an oxygen debt is created.

32 © Boardworks Ltd of 36 It is the oxygen needed to get rid of lactic acid that pays back the oxygen debt. Oxygen debt – pay off The oxygen debt caused by anaerobic respiration is paid off during the recovery period after exercise. carbon dioxide lactic acid oxygen water oxygen to pay back ‘oxygen debt’ When is the oxygen debt completely paid off?

33 © Boardworks Ltd of 36 Anaerobic respiration: word equation activity

34 © Boardworks Ltd of 36 Contents Respiration Anaerobic respiration Summary activities Releasing energy Rate of respiration Aerobic respiration

35 © Boardworks Ltd of 36 Which type of respiration?

36 © Boardworks Ltd of 36 Multiple-choice quiz


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