10.3b Anaerobic respiration in yeast

• Compare anaerobic respiration in humans and yeast

  Anaerobic respiration in humans and yeast both occur without oxygen, but they have different end products. In humans, anaerobic respiration produces lactic acid, while in yeast, it produces ethanol and carbon dioxide.
• Know the associated variables to the yeast and balloon experiment.

  The associated variables for anaerobic respiration in both humans and yeast include the initial concentration of glucose or another fermentable substrate, temperature, pH level, and the presence or absence of specific enzymes involved in the respective metabolic pathways.
• Describe the effect that temperature has on yeast

  Temperature affects yeast growth and activity. In general, warmer temperatures speed up yeast metabolism, leading to faster fermentation rates. However, if it gets too hot, it can kill yeast cells, while colder temperatures slow down yeast activity. So, the ideal temperature for yeast depends on the specific strain and the desired fermentation outcome.
• Write the equation for anaerobic respiration in yeast 

  The equation for anaerobic respiration in yeast is:

  Glucose → Ethanol + Carbon Dioxide + Energy
• State how we know that yeast make carbon dioxide

  We know that yeast produce carbon dioxide because bubbles of gas are observed during fermentation, such as in bread dough rising.
• Describe how temperature affects respiration rate

  temperature impacts respiration rate by directly influencing the activity of enzymes involved in the process. When it's warmer, enzyme activity increases, leading to a faster respiration rate. Conversely, colder temperatures slow down enzyme activity and thus reduce respiration rate. However, extreme temperatures can denature enzymes, causing respiration to halt. So, there's an optimal temperature range where respiration operates most efficiently.
• Be familiar with the yeast and balloon experiment 

  In the yeast and balloon experiment, yeast is mixed with sugar and warm water in a bottle. As the yeast ferments the sugar, it produces carbon dioxide gas, which inflates a balloon attached to the bottle's opening. This demonstrates anaerobic respiration in yeast and the production of carbon dioxide gas as a byproduct. It's a simple and visual way to observe fermentation in action.
• State why high temperatures stop respiration

  High temperatures stop respiration because they cause enzymes involved in the process to denature, meaning they lose their shape and can no longer function properly.
• Know the independent variable related to the experiment

  The independent variable in the yeast and balloon experiment is typically the concentration of sugar or glucose added to the yeast mixture. By varying the amount of sugar, you can investigate how different sugar concentrations affect the rate of fermentation and the amount of carbon dioxide produced.
• Know the dependent variable related to the experiment

  The dependent variable in the yeast and balloon experiment is the size or volume of the balloon, showing the amount of carbon dioxide produced during fermentation.
• Know the variables that should be controlled in tthe yeast and balloon experiment

  Variables to control: Temperature,  Type and amount of yeast, Volume of liquid ,        Type and amount of sugar, Time, Size and type of balloon
• Describe the results observed in the experiment 

  In the yeast and balloon experiment, the observed results typically include the inflation of the balloon attached to the bottle's opening. As fermentation occurs, carbon dioxide gas is produced by the yeast, causing the balloon to inflate. The size or volume of the inflated balloon can vary depending on factors like the concentration of sugar, the type of yeast used, and the duration of the experiment. Overall, the larger the balloon, the more carbon dioxide has been produced, indicating a higher rate of fermentation.