<p> CHAP. 2 – SEC. 2: RESPIRATION</p><p>The food you eat provides you with chemical potential energy.</p><p>It is chemical potential energy because the energy is not immediately converted to use.</p><p>To convert the food to energy, it must go through the following steps:</p><p>1. The food must be digested which means breaking food down into smaller molecules.</p><p>2. The small molecules pass out of your digestive system and directly into your bloodstream.</p><p>3. Once it your bloodstream, it travels to your cells.</p><p>4. Once inside the cells, the molecules are transformed into energy through a process called cellular respiration.</p><p>I. STORING & RELEASING ENERGY</p><p>The reason that food is not immediately converted into energy is because your body usually does not need the </p><p>1 energy right away. The energy from food is stored in the cells for later use.</p><p>Plants save the energy made in photosynthesis in the form of carbohydrates: starches (potatoes) and sugars (celery).</p><p>When plant needs energy, it breaks down the carbohydrates and the process of breaking down the carbohydrates releases energy.</p><p>II. RESPIRATION</p><p>After you eat a carbohydrate, your body stores the energy in it as glucose (a type of sugar).</p><p>If you need the energy in the glucose, your body breaks down the sugar in a process called CELLULAR RESPIRATION.</p><p>III. THE RESPIRATION EQUATION</p><p>C6H12O6 + 6O2  6CO2 + 6H2O + energy glucose oxygen Carbon water dioxide The glucose comes from storage in the cells and from the food animals consume.</p><p>2 The oxygen comes from the air animals breathe in or water for aquatic organisms.</p><p>Notice that the raw materials in cellular respiration are the output products of photosynthesis.</p><p>Notice that the output products of photosynthesis are the raw materials for cellular respiration.</p><p>IV. TWO STAGES OF RESPIRATION</p><p>A. FIRST STAGE</p><p>This takes places in the cytoplasm of the cells where large glucose molecules are broken down into smaller ones.</p><p>Only a small amount of energy is released when the glucose molecules are broken down.</p><p>B. SECOND STAGE</p><p>The second stage takes place in the mitochondria.</p><p>Small molecules are broken down into even smaller molecules in the mitochondria.</p><p>3 Oxygen is required in this stage and a great deal of energy is released.</p><p>Hence, why mitochondria are called the cell’s powerhouse.</p><p>C. THE PRODUCTS OF CELLULAR RESPIRATION</p><p>The products or results of cellular respiration are energy, carbon dioxide, and water.</p><p>Energy gets used immediately by the body.</p><p>Carbon dioxide and water diffuse out the cells and out of the body when you breathe out.</p><p>When you breathe in, you take in oxygen – a needed material to undergo cellular respiration.</p><p>V. COMPARING PHOTOSYNTHESIS & RESPIRATION</p><p>The equation for photosynthesis is the opposite for cellular respiration.</p><p>4 Together, the two energy cycles keep the levels of oxygen and carbon dioxide in balance.</p><p>However, in today’s climate, too much carbon dioxide is being produced by humans, animals, and machines.</p><p>Plants and trees are being cut down and cannot consume all the carbon dioxide or give us the oxygen we need to live.</p><p>As a result, excess carbon dioxide is sticking to our atmosphere causes the earth to heat up – known as global warming.</p><p>The electromagnetic waves that come to earth normally bounce back into space.</p><p>With a thickening atmosphere, it is trapped on the earth causing the earth to heat up.</p><p>VI. FERMENTATION</p><p>There are organisms on this earth that can obtain energy from food WITHOUT USING OXYGEN.</p><p>These organisms obtain energy from a process called fermentation.</p><p>5 The amount of energy released from each glucose molecule during fermentation is much lower than the amount released during respiration.</p><p>A. ALCOHOLIC FERMENTATION</p><p>This is fermentation in yeast and other single celled organisms.</p><p>It is called alcoholic fermentation because alcohol is released as a product when the sugars are broken down.</p><p>Also released are carbon dioxide and energy.</p><p>Fermentation is important to bakers and brewers.</p><p>For bakers, carbon dioxide causes the bread to rise and creates air pockets.</p><p>For brewers, carbon dioxide is the source of the bubbles in beer and the alcohol is the basis for the all alcoholic drinks.</p><p>6 B. LACTIC-ACID FERMENTATION </p><p>There are times when you push your body so hard that cellular respiration cannot keep up and give you the energy you need.</p><p>When your body lacks the oxygen it needs to undergo cellular respiration, it will switch to fermentation.</p><p>You feel fermentation as a painful, burning sensation in your muscles.</p><p>The burning is caused by the product of fermentation called LACTIC ACID.</p><p>7</p>