Respiration

1. Respiration

2. Respiration • 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 • Word equation for aerobic respiration: Glucose + Oxygen -> Carbon Dioxide + water + Energy • Equation for aerobic respiration using symbols: (C6H12O6 + 6O2 → 6CO2 + 6H2O+ energy in ATP form)

3. Anaerobic respiration as the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen • Word equation for anaerobic respiration in muscles during hard exercise: (glucose → lactic acid) • Balanced equation for anaerobic respiration in muscles: (C6H12O6 → 2C3H6O3)

4. microorganism yeast: (glucose→ alcohol + carbon dioxide) • (C6H12O6 →2C2H5OH + 2CO2)

5. Describe the role of anaerobic respiration inyeast during brewing and bread-making • Anarobic Respiration in yeast during brewing: • - Yestis used in the production of several types of beers including lagers. And ales . • Yeast is cultured in huge bins under anaerobic conditions. • Yeast converts the sugar in grapes to alcohol and carbon dioxide. • A one-way valve allows the carbon dioxide to escape without letting any oxygen in. • The bubbles are left dissolved in the bins when making sparkling wines such as Champagne

6. One yeast cell can approximately ferment its own weight in glucose in an hour. The yeast can produce an average of 15 to 16% of ethanol by weight. • Yeast can produce up to 18 percent ethanol, by volume • Any more ethanol is toxic to the cells and causes yeast cell to die. • Sulphur dioxide is added to kill naturally present bacteria and moulds. • There are basically two major kinds of yeast used in brewing. Ale yeast works at about room temperature, ferments quickly, and produces the pleasant "fruitiness" characteristic of most ales. • Lager yeast works at cold temperatures (30 to 40 degrees Fahrenheit), ferments more slowly, and produces the clean taste of a lager beer. Within each of these two types are literally hundreds of different strains of yeast.

7. Bread making • The tantalizing aroma of bread baking in the bakery is due to a process called fermentation of baker's yeast • Yeast have long been utilized to ferment the sugars of rice, wheat, barley, and corn to produce alcoholic beverages and in the baking industry to expand, or raise, dough.

8. Dry yeast available in the grocery store is a collection of dormant yeast spores. • Once these spores are mixed into water and dough, the culture is active. • To start this germination process and make the bread rise faster, the baker sometimes mixes yeast with water or milk before adding to the dough. • The yeast's function in baking is to ferment sugars present in the flour or added to the dough. • This fermentation gives off carbon dioxide and ethanol. • The carbon dioxide is trapped within tiny bubbles and results in the dough expanding, or rising. • Their usefulness is based on their ability to convert sugars and other carbon sources into ethanol in the absence of air (anaerobic), and into carbon dioxide and water in the presence of air (aerobic).

9. Compare aerobic respiration and anaerobic respiration in terms of relative amounts of energy released

10. Describe the effect of lactic acid in musclesduring exercise (include oxygen debt in outline only) • Our muscles can run out of oxygen when we work hard • They can keep going by respiring anaerobically for a short time • When anaerobic respiration happen in humans lactic acid is produced • Lactic acid is toxic

11. When it builds up in muscle – it is painful and causes cramps • This is why muscles can respire for a short time anaerobically • Lactic acid diffuses into blood from muscles and is taken to the liver because extra oxygen is needed • This is why we start panting – to get more oxygen • You are paying your “oxygen debt” while your muscles were respiring anaerobically