How To Understand The Chemistry Of Respiration

Transcription

1 MODULE 02 Respiration and Gas Exchange This is one of the characteristics of living things. We will study this in both plants and humans. Gas exchange structures and how they facilitate gas exchange in humans Respiration as a chemical process with and without oxygen You will be able to:- *Higlighted pages are from MacKean **Italic pages are from the IGCSE book NOTE although Mackean is on the booklist it is here simply to supplement the information in the IGCSE textbook. Mackean contains more detail and may be useful to supplement or give additional information on a particular topic. This is a new section in your notes covering part of chapter 9 page 112,

2 Respiration Define respiration as the chemical reactions that break down nutrient molecules in living cells to release energy Chapter 3 Page 19. Page 112 chapter 9 Make a note of the definition of RESPIRATION as the chemical process which releases energy from food.. State the uses of energy in the body of humans: muscle contraction, protein synthesis, cell division, active transport, growth, the passage of nerve impulses and the maintenance of a constant body temperature You need to know the reasons why organisms need energy. There is a list on page 112. Aerobic respiration Define aerobic respiration as the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen Page 113. There is a definition here which needs to be learned. Note that aerobic respiration releases a large amount of energy Familiarise yourself with the experiment to demonstrate respiration in peas you might be able to try this yourself. State the word equation for aerobic respiration Make a note of the word equations for aerobic respiration and be able to describe the process page 113. State the equation for aerobic respiration using symbols (C6H12O6 + 6O2 6CO2 + 6H2O) You also need the equation in symbols if you are doing the higher tier.. Anaerobic respiration Define anaerobic respiration as the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen Page 115 make a note of the definition of anaerobic respiration here. This needs to be learned. Note there is a different equation for plants and animals. Remember the key difference is that anaerobic respiration occurs in the ABSENCE of oxygen State the word equation for anaerobic respiration in muscles during hard exercise (glucose lactic acid) and the microorganism yeast (glucose alcohol + carbon dioxide) You also need to learn the word equation for anaerobic respiration Page 115

3 Compare aerobic respiration and anaerobic respiration in terms of relative amounts of energy released Anaerobic respiration releases a much smaller amount of energy than aerobic respiration. Make sure you make notes on this process and learn them. Look at the comparison table of aerobic and anaerobic respiration. Copy out this table into your notes and learn these differences. Page 115 &123 remember that during anaerobic respiration animals produce lactic acid and plants produce ethanol (alcohol). NOTE that in animals NO carbon dioxide is produced during anaerobic respiration. State the balanced equation for anaerobic respiration in muscles (C6H12O6 2C3H6O3) and the microorganism yeast (C6H12O6 2C2H5OH + 2CO2), using symbols If you are doing the higher tier you need to learn the equation in symbols for anaerobic respiration. Describe the role of anaerobic respiration in yeast during brewing and bread-making Page 115 The anaerobic respiration of yeast is used in both brewing and bread making. You need to know what happens during brewing and bread making. Make notes on this Describe the effect of lactic acid in muscles during exercise (include oxygen debt in outline only) Page 123 You should be able to explain what happens when lactic acid builds up in muscles and what the term oxygen debt means. This explains why you should cool down after exercise. So you shouldn t suddenly stop exercising, but do some gentle stretching exercises or walking. Gas exchange List the features of gas exchange surfaces in animals Page 116/117 write down the features of a gas exchange surface Identify on diagrams and name the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries Page 117 Make a large labelled diagram in your notes of the gas exchange system in humans ( you might find a better diagram on the internet than

4 in your text). For each of the following briefly describe the structure (2-4 sentences should be enough) and function of each of the following RIBS, INTERCOSTAL MUSCLES, DIAPHRAGM, TRACHEA, BRONCHI, BRONCHIOLES, ALEOLI and PLEURAL MEMBRANES Explain the role of mucus and cilia in protecting the gas exchange system from pathogens and particles Make sure you understand the function of the lining of the trachea in terms of removing particles from inhaled air. Fig 9.2 Pg 118 Describe the role of the ribs, the internal and external intercostal muscles and the diaphragm in producing volume and pressure changes leading to the ventilation of the lungs Pg Fig 13.6 & 13.7 make sure you understand the sequence of events leading to air being drawn into the lungs. Try and put these in bullet points pay particular attention to the volume and pressure changes in the thorax. Explain precisely what happens in the alveoli and what the adaptaions are which make the alveoli effective in absorbing gases. Page 119 Look at the diagrams on page 121 and explain what is happening here. fig LEARN THE SEQUENCE OF EVENTS. This comes up frequently in exams State the differences in composition between inspired and expired air Use lime water as a test for carbon dioxide to investigate the differences in composition between inspired and expired air Draw the table comparing inhaled and exhaled air. Page 122. Look at the activity 9.5 which uses indicators to detect the presence of carbon dioxide. Make sure you know what these two indicators are and the changes which take place to indicate the presence of carbon dioxide. Page 123remember that plants also respire and need to take in oxygen. They respire all the time, but also photosynthesise in the light. This produces oxygen as a waste product, some of which is used in respiration. At night they can t photosynthesis so have to take in more oxygen and give out carbon dioxide. During the day this carbon dioxide is used in photosynthesis.

5 Investigate and describe the effects of physical activity on rate and depth of breathing Explain the link between physical activity and rate and depth of breathing in terms of changes in the rate at which tissues respire and therefore of carbon dioxide concentration and ph in tissues and in the blood You can try to see what the effect of exercise is on your breathing rate. Observe your breathing rate at rest and then do some vigorous exercise and see how your breathing changes. Try to explain this.. Describe the effects of tobacco smoke and its major toxic components (tar, nicotine, carbon monoxide, smoke particles) on the gas exchange system. Make notes on the effect of smoking on the gas exchange system from page 162. You should concentrate on the effects of the different components of cigarette smoke ie carcinogens & irritants, nicotine and carbon monoxide