UNIT 2 Getting energy from food

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1 Biology Form 4 Page 16 Ms. R. Buttigieg UNIT 2 Getting energy from food 2.1 Aerobic and anaerobic respiration (see GSCE Biology pg ) RESPIRATIO the process by which energy is produced from food Energy produced during respiration is used for: a. Chemical reactions b. Making muscles work - movement c. Growth and repair of cells d. Making up larger molecules from smaller ones e. Maintaining body temperature in warm blooded animals f. For active transport

If the cell needs energy it breaks the ATP molecules and energy is released into the cell.

2 Biology Form 4 Page 17 Ms. R. Buttigieg Energy released during respiration is stored in the form of a molecule called ATP (adenosine triphosphate). If the cell needs energy it breaks the ATP molecules and energy is released into the cell. Aerobic Respiration Anaerobic Respiration Oxygen is required. No oxygen is required 16.1 kj/g glucose released 1.2 kj/g glucose released in fermentation by yeast 0.8 kj/g glucose released in anaerobic respiration in muscles. 38 ATP molecules 2 ATP molecules produced produced

3 Biology Form 4 Page 18 Ms. R. Buttigieg 1. Complete: Respiration takes place in all our. The fuel for respiration is. It is broken down to release. Also produced are water and the waste gas. When it takes place in the presence of we call it respiration. These reactions take place in every living cell, inside tiny structures called. 2. Give 2 differences between aerobic and anaerobic respiration: Answer the following: 3. What is aerobic respiration in yeast called? 4. How is lactic acid removed from cells? 5. Which type of respiration results in the most energy being produced? 6. Name 2 commercial uses of anaerobic respiration: 7. Write down the word equation for aerobic respiration: 8. Write down the word equation for fermentation: 9. Give 5 reasons why respiration is important in different living organisms: a. b. c. d. e. 10. Respiration is

4 Biology Form 4 Page 19 Ms. R. Buttigieg A note on ATP Adenosine triphosphate - ATP Adenosine P P P + Adenosine P P + P + Energy Adenosine diphosphate - ADP The energy released from glucose is used to build ATP from ADP and P (phosphorus) The ATP molecules formed are then transported to all parts of the body, and are broken down to provide energy where it is needed. So we say that ATP is an energy carrier as it carries energy from the site of respiration (the mitochondrion) to every part of the body that requires energy. Work out: - GCSE Biology pg. 20 numbers 1-5 Use the internet, books in the library, encyclopaedias or other resources to write 100 words on three of the following: a. Making alcohol b. Bread making c. Making yoghurt d. Production of biogas e. Silage f. Making butter.

This process is called FERME TATIO This is used in making: Wine Beer Wine is made from grapes. After they are crushed and the juice (containing sugar and wild yeast) is extracted.

5 Biology Form 4 Page 20 Ms. R. Buttigieg 2.2 Economic importance of products derived from anaerobic respiration of certain micro organisms a. Alcohol production - Sugar can be broken down by yeast cells to produce alcohol, carbon dioxide and energy. This process is called FERME TATIO This is used in making: Wine Beer Wine is made from grapes. After they are crushed and the juice (containing sugar and wild yeast) is extracted. The yeast ferments the sugar and turns it into alcohol. o The flavour depends on the type of grapes used and conditions of fermentation. Beer is made from barley. This is called brewing. The malt sugar in the grain is mashed with water, yeast and flavour is added by boiling with flower of climbing plants (hops). b. Vinegar production Vinegar is made by the action of certain bacteria, which convert alcohol into acid. c. Bread making Bakers mix flour and water with a little sugar and add yeast. It is then left for some time in a warm place to ferment (fermentation is faster in warm conditions). Yeast changes sugar to produce alcohol and carbon dioxide. The gas makes the dough rise. The baking of the dough then kills the yeast and causes the alcohol to evaporate.

Biology Form 4 Page 21 Ms. R. Buttigieg d. Yoghurt Milk is pasteurised, and then certain types of bacteria (like Lactobacillus) are added to the milk to ferment it.

6 Biology Form 4 Page 21 Ms. R. Buttigieg d. Yoghurt Milk is pasteurised, and then certain types of bacteria (like Lactobacillus) are added to the milk to ferment it. The inoculated (has bacteria in it), warm pasteurised milk is poured into containers and capped. Preserves, flavourings and sugars may also be added. The milk containers are held at 44 o C for several hours. This is the ideal temperature for the bacteria to grow, multiply and produce the lactic acid that thickens and sours the milk. Sterilized fruits can be added. The yoghurt is then chilled to 7 o C. It keeps well for about a week in the refrigerator. e. Butter Bacteria are added to milk products (cream). The bacteria make it sour, give flavor and aid the separation of the butterfat. The mixing of this butterfat makes butter. f. Biogas 1 Biogas typically refers to methane produced by the fermentation of organic matter including manure, wastewater sludge, or municipal solid waste, under anaerobic conditions. The process is popular in rural areas, because it provides a convenient way of turning waste into electricity. The gas can then be used for lighting, cooking, as diesel substitute and for refrigerators. The use of biogas is encouraged because methane burns with a clean flame and produces little pollution. Other sources of biogas are landfills and sewage treatment plants. Manure digestion occurs in a digester, which must be strong enough to withstand the buildup of pressure and must provide anaerobic conditions for the bacteria inside. Digestors are usually built near the manure source, and several are often used together to provide a continuous gas supply. The sludge left can also be used as fertiliser. g. Silage 2 Silage is most often made from grass crops, including corn (maize) or sorghum. Silage is made from the entire plant, not just the grain. Silage can also be made from many other field crops and sometimes a mixture is used, such as oats and peas. Grass is cut, packed tightly in a pit or container so oxygen cannot get into it. Without oxygen the grass is prevented from decaying any further and this results in silage. Hay results when the grass is dried. 1 See 2 See:

oxygen is present. Imagine you are running a race. If your heart and lungs can t supply the oxygen fast enough, the muscle cells will begin to respire anaerobically to produce more energy.

7 Biology Form 4 Page 22 Ms. R. Buttigieg 2.3 Anaerobic respiration in muscles (see also notes pg. 19) Anaerobic respiration is generally defined as respiration occurring in the absence of oxygen, but this is not the case for the skeletal muscle, which can carry out anaerobic respiration even when oxygen is present. Imagine you are running a race. If your heart and lungs can t supply the oxygen fast enough, the muscle cells will begin to respire anaerobically to produce more energy. During anaerobic respiration in animals, glucose is broken down into lactic acid, and a small amount of energy is released. It produces far less energy than aerobic respiration because the glucose is not completely broken down to carbon dioxide and water, so not all the stored energy is released. The lactic acid produced is toxic and causes the muscles to ache. In high concentrations it causes cramps. The cramp disappears as the lactic acid dissolves in the plasma of blood, and is taken to the liver. That is why after you stop exercising, you continue to breathe deeply. This is to supply enough oxygen to combine with the lactic acid in order to oxidize it to carbon dioxide and water. A small amount of energy is released. The amount of oxygen required to break down the lactic acid formed during exercise is called the oxygen debt. Remember! All these reactions are controlled by enzymes. i ATP supplies in muscles provide enough energy only for the first few seconds of exercise i Anaerobic respiration can supply energy only for up to two minutes of high intensity exercise i Aerobic respiration can supply energy indefinitely for low intensity activity

8 CO 2 CO 2 Biology Form 4 Page 23 Ms. R. Buttigieg 2.4 Characteristics of respiratory surfaces (see also notes pg. 19) A respiratory surface must have the following characteristics (GSCE Biology pg. 126) 1. Large surface area 2. Thin 3. Moist 4. A concentration gradient There are other factors involved, e.g. where appropriate, a good blood supply to carry the oxygen away to the tissues and to maintain a steep concentration gradient. The process of diffusion will be faster in warm conditions as molecules have more energy and therefore move faster. So temperature will also affect the efficiency of the diffusion. While small organisms use their surface for gas exchange, larger organisms have developed fairly complex respiratory systems. In most cases these are coupled with a transport system to increase the efficiency of gaseous exchange. In this topic we shall be looking at how gaseous exchange occurs in different organisms. o Protist (see GSCE Biology pg. 298) o Insect o Fish (see GSCE Biology pg ) o Flowering Plant (see GSCE Biology pg. 298) o Human (see GSCE Biology pg ) Gas Exchange in unicellular organisms Unicellular Organisms do not have specialized gas exchange surfaces. Instead gases diffuse in through the cell membrane. The smaller something is, the smaller the surface area is but, more importantly, the bigger the surface area is compared to its volume large surface area to volume ratio. Also, all parts of the organism are supplied with oxygen because the diffusion path is short. Oxygen continuously diffuses in, while carbon dioxide produced by respiration diffuses out. O 2 O 2 CO 2

Biology Form 4 Page 24 Ms. R. Buttigieg Gas Exchange in Insects Insects have a small surface area to volume ratio compared to protists. Insects do not breathe through their mouths as we do.

These spiracles are found on each side of the insect's abdomen.

similar way to the bronchioles in our lungs. The tracheae finally come to an end in the tissues, which are respiring. Here in the tissues the oxygen is taken from the air in the tracheae.

9 Biology Form 4 Page 24 Ms. R. Buttigieg Gas Exchange in Insects Insects have a small surface area to volume ratio compared to protists. Insects do not breathe through their mouths as we do. They have a system of tubes, called tracheae, instead of lungs. (a tracheal system) These tracheae penetrate right through the insect's body. Air enters the tracheae by pores called spiracles. These spiracles are found on each side of the insect's abdomen. Each segment of the abdomen has a pair of spiracles The air passes into the tracheae which branch into smaller and smaller tubes (called tracheoles which have a watery fluid in their tips), in a similar way to the bronchioles in our lungs. The tracheae finally come to an end in the tissues, which are respiring. Here in the tissues the oxygen is taken from the air in the tracheae. At the same time carbon dioxide enters the tracheae so that it can be expelled from the body. The process of breathing in insects is slow. In very active insects air is moved in and out of the tubes by contraction of the insect s abdominal muscles. The spiracles on the sides of the insect's body can be closed by valves. (see the diagram above) It is difficult to drown an insect because, when it is under water, it closes the valves. This prevents water entering the tracheae and, with air in its body, the insect will tend to float. Gas Exchange in Fish Fish have internal gills, which are covered by an operculum. To get enough oxygen the fish must make water flow across its gills. The fish does not breathe water in and out of its mouth. The drawing on the next page shows the water entering the fish's mouth and crossing the gills.

Biology Form 4 Page 25 Ms. R. Buttigieg The water gives oxygen to the blood in the gill filaments and receives carbon dioxide in exchange. Finally, the water passes out from under the operculum.

They require oxygen for respiration and carbon dioxide for photosynthesis. The gases diffuse into stomata. From these spaces they will diffuse into the cells that require them.

10 Biology Form 4 Page 25 Ms. R. Buttigieg The water gives oxygen to the blood in the gill filaments and receives carbon dioxide in exchange. Finally, the water passes out from under the operculum. The blood in the gills then transports oxygen to all parts of the body. Gas Exchange in Plants Plants obtain the gases they need through their leaves. They require oxygen for respiration and carbon dioxide for photosynthesis. The gases diffuse into stomata. From these spaces they will diffuse into the cells that require them. Stomatal opening and closing depends on changes in the turgor of the guard cells. Respiration occurs throughout the day and night, providing the plant with a supply of energy. Photosynthesis can only occur during sunlight hours so it stops at night. A product of respiration is carbon dioxide. This can be used directly by the plant in photosynthesis. However, during the day, photosynthesis can be going 10 or even 20 times faster than respiration, so the stomata must stay open so that the plant has enough carbon dioxide, most of which diffuses in from the external atmosphere.

Biology Form 4 Page 26 Ms. R. Buttigieg Gas Exchange in Humans (see GSCE Biology pg. 123-30) Make sure you re capable of drawing and labelling the various parts of the lungs (see Fig 13.1 pg.

The main muscles involved and how they act diaphragm and intercostal muscles (see pg. 124, fig. 13.4) The mechanism involved when inhaling and exhaling (text and figure 13.6, 13.7, pg.

passes into the lungs while carbon dioxide moves in the opposite direction and leaves the body with exhaled air.

11 Biology Form 4 Page 26 Ms. R. Buttigieg Gas Exchange in Humans (see GSCE Biology pg ) Make sure you re capable of drawing and labelling the various parts of the lungs (see Fig 13.1 pg. 123) The Air passage into the various lung structure from the trachea to the alveoli (fig pg. 124) Work out GCSE Biology pg. 123 number 1. The main muscles involved and how they act diaphragm and intercostal muscles (see pg. 124, fig. 13.4) The mechanism involved when inhaling and exhaling (text and figure 13.6, 13.7, pg. 125) Recognise the difference between breathing (forcing air into and out of the body) and respiration (breaking down food to obtain energy) When we inhale (breathe in) oxygen enters the nose and passes into the lungs while carbon dioxide moves in the opposite direction and leaves the body with exhaled air. Comparing the percentage of Inhaled and Exhaled Gases Gases % in inhaled Air % in exhaled air Oxygen 21 % 16% Carbon dioxide 0.04 % 4% Nitrogen 79 % 79% Water vapour A little A lot Inhaled and exhaled air have different compositions of gases. Which three of the following apply to inhaled air? Contains 21% oxygen Contains 0.04 % carbon dioxide Contains the same amount of water vapour as the atmosphere Contains about 4% carbon dioxide Contains 16% oxygen An important feature is the presence of cilia (small hairs) and mucus that trap dust particles, and harmful organisms such as bacteria and prevent them from reaching the alveoli. The cilia push the mucus upwards and eventually it passes into the gullet and the contents are swallowed and destroyed in the digestive system. This helps reduce the chance of infections.

12 Biology Form 4 Page 27 Ms. R. Buttigieg A brief overview A) Air enters the Respiratory System through the Mouth or ose. Breathing through the nose is healthier than breathing through the mouth as: The Air is filtered The Air is warmed Moisture(water vapour) is added to the Air Chemicals in the air are detected by olfactory cells. The moisture in the nose helps to heat and humidify the air, increasing the amount of water vapour the air entering the lungs contains. This helps to keep the air entering the nose from Drying out the Lungs and other parts of our Respiratory System. B) As air pushes back from the Nasal Cavity, it enters the PHARY X. The Pharynx is located in the back of the mouth and serves as a passageway for both air and food. When food is swallowed, a flap of cartilage called the EPIGLOTTIS, presses down and covers the opening to the air passage. C) From the Pharynx, the air moves through the LARY X, and into the: D) TRACHEA (WINDPIPE), which leads to the lungs. The Walls of the Trachea are made up of tough flexible Cartilage which: o protects the trachea, o makes it flexible, and o keep it from collapsing or over expanding. The trachea divides into the Right and Left BRO CHI. Each BRONCHUS enters the LUNG on its respective side and divides into BRO CHIOLES.

Biology Form 4 Page 28 Ms. R. Buttigieg The Bronchioles continue to subdivide until they finally end in clusters of tiny hallow air sacs called ALVEOLI.

13 Biology Form 4 Page 28 Ms. R. Buttigieg The Bronchioles continue to subdivide until they finally end in clusters of tiny hallow air sacs called ALVEOLI. It is here that the Circulatory and Respiratory Systems come together, for the purpose of gas exchange. Each Lung contains nearly 300 Million ALVEOLI and has a total surface area about 40 times the surface area of your skin. Regulation of Breathing Breathing is such an important function that the nervous system will NOT let you have complete control of it. Breathing in an involuntary action under the control of the medulla oblongata in the lower part of the brain. Rate of breathing can be varied either by your decision (conscious) during exercise as the level of carbon dioxide in the blood increases. This rise is detected by receptors in the aorta and carotid arteries, causing an increase in breathing rate and depth of breathing. The Lungs of an average person have a total air capacity of about 6.0 litres. Only about 0.6 litres are exchanged during normal breathing. This is all the air we need at rest. GAS EXCHA GE I THE ALVEOLI When inspired air reaches the alveoli, oxygen and carbon dioxide are exchanged by diffusion. Oxygen Passes from air to capillaries Because higher concentration of oxygen in the alveoli Carbon dioxide Passes from capillaries to alveoli Because higher concentration in the capillaries The alveoli aren t completely emptied of air when we breathe out. Some air remains trapped inside them, or they will stick together and breathing problems will result.

14 Biology Form 4 Page 29 Ms. R. Buttigieg 2.5 Health hazards connected with breathing Smoking - For the information regarding this section see GCSE Biology pg Note in particular the dangers of lung cancer, bronchitis, emphysema and the dangers of passive smoking Air pollution - This also poses a hazard to human health and in some cases interferes with the gas exchange (respiratory) system. (see GCSE Biology pg ) Pollutant Source Effect on Health Possible solutions Carbon Modify car engines monoxide Excess Carbon dioxide Sulphur dioxide SO 2 Nitrogen dioxide NO 2 CFCs Incomplete combustion of fuels containing carbon in vehicle exhaust Burning of fossil fuels. Burning of fossil fuels containing sulphur Petrol engines ignite the petrol-air mixtures by a spark. This spark helps nitrogen to combine with oxygen producing nitrogen oxides. Aerosol sprays, Refrigerants and coolants Poisonous and odorless that is why it is so dangerous. Binds to heamoglobin and prevents transport of oxygen. A greenhouse gas that causes greenhouse effect Can damage the lungs and lead to bronchitis It is a poisonous gas and causes acid rain which lowers soil and water ph causing the death of fish and also damages buildings Same as above Depleting the ozone layer which protects us from harmful UV light of the sun skin cancers Plant more trees Find other energy sources other than fossil fuels Modify car engines Install catalytic converters in cars Desulphurisation Install chimney filters Modify car engines Use catalytic converters Install chimney filters Manufacture of ozone friendly products Ban of substances containing CFCs Lead vapour Smoke Asbestos particles Cars working with leaded petrol Fuels that burn with a smoky flame Poisonous Soot causes damage to the lungs and may lead to asthma, irritate the lungs and cause bronchitis. Coats alveoli and prevents gas exchange Cause lung cancer Use of unleaded petrol Use chimney filters Ban its use Importance of alternative energy sources such as wind energy, solar energy, tidal energy and batteries

15 Biology Form 4 Page 30 Ms. R. Buttigieg FILL I THE BLA KS 1. The grape-like clusters of air sacs within the lungs are the. 2. The lungs are covered by the. 3. What three things happen to air as it passes through the nose? a. b c. 4. The chest cavity is separated from the abdominal cavity by the. 5. The oxygen-carrying molecule in blood is. 6. The main job of the respiratory system is to get into the body and out of the body. 7. The walls of the trachea are made up of rings of. 8. What muscles are used in the breathing process? 9. There are two sets of receptors that constantly check the levels of gases in our blood. Say where they are they located in the body?. MATCHI G 1. Sponge like organs located in the chest a. Epiglottis 2. Chamber where passages from the nose b. Trachea and mouth come together 3. Muscular organ between the pharynx and c. Bronchioles the trachea 4. Elastic tissue that forms a flap over the top d. Pharynx of the larynx 5. Main passageway to the lungs e. Alveoli 6. Tubes that branch from the trachea f. Larynx 7. Small tubes that branch from the bronchi g. Bronchi 8. Tiny air sacs in the lungs h. Lungs

16 Biology Form 4 Page 31 Ms. R. Buttigieg Answer the following: 1. Match the terms in LIST A with the descriptions in LIST B LIST A LIST B 1. Diffusion i process of increased movement of water molecules through a selectively permeable membrane to a more concentrated solution. 2 Freely permeable membrane ii the movement of substances, across a cell membrane, against a concentration gradient. 3 Selectively permeable membrane iii movement of molecules of a substance from high to low concentration. 4 Osmosis iv term to describe structure that allows rapid passage of all molecules in solution. 5 Active transport v structure that allows small molecules to pass through, but larger ones are held back. RESULTS: Read the following paragraph and then answer the set questions. (5 marks) For a long time there has been a lot of argument over whether smoking really does cause harm to our health. Now, there is a lot of evidence to show what the effects of smoking are. A number of serious diseases have been shown to be connected with smoking and air pollution. All human beings need to breathe in air to get oxygen. For aerobic respiration to occur, alveolar gaseous exchange must follow inhalation. Active smoking directly affects gaseous exchange. However, passive smokers are also in danger. a. What do you understand by passive smokers? (1) b. ame 2 diseases that are linked with smoking and write a short note about one of them. (2, 2) c. State two differences between aerobic and anaerobic respiration. (2) d. Describe, with the help of a clear labelled diagram, alveolar gaseous exchange in humans. (3) e. Name two characteristics of an efficient respiratory surface. (2) f. Describe briefly the mechanism involved during breathing in (INHALING). (3) (total 15 marks) JL This question is about Gas Exchange. a) Define the word breathing (2) b) Name two structures which help the breathing movements in the human body. (2) c) Breathing through the nose is healthier than breathing through the mouth. Give your comments about this statement. (3) d) Strenuous exercise effects both the breathing rate as well as the heart rate. Describe an experiment to show that strenuous exercise effects the heart rate. (5) e) Mammals breathe through lungs and fish breathe through gills. List three characteristics; common to these two breathing organs, which make them both efficient respiratory surfaces. (3) (total 15 marks) JL 2003

08 Respiration. #79 Respiration realeases energy from food

08 Respiration. #79 Respiration realeases energy from food 08 Respiration #79 Respiration realeases energy from food Respiration is the chemical reactions that break down nutrient molecules in living cells to release energy. In humans, our cells need energy (ATP)