Objectives: • To be able to define cellular respiration and fermentation. • To give the overall balanced equations for aerobic respiration and alcoholic fermentation. • To distinguish between inputs, products, and efficiency of aerobic respiration and those of fermentation. • Understand the relationship between respiration and photosynthesis.
Note: You should perform experiments as described in this handout, which are adapted from Starr and Taggart’s Lab Manual for Biology (pp.131-142). Answer the questions in this handout as you wait for results to be seen. If this lab is to be used for a lab report, consider these questions when compiling the report.
The first law of thermodynamics states that energy can neither be created nor destroyed, but only converted from one form to another. All living organisms have a constant energy requirement; therefore, they have biochemical mechanisms that allow them to gather, store, and use energy. These mechanisms are collectively known as metabolism. A sequence of reactions must occur with each mechanism of metabolism, forming metabolic pathways.
When we study photosynthesis in next week’s lab, you will investigate the metabolic pathways in which green plants capture light energy to produce the carbohydrate known as glucose. Carbohydrates can be used as temporary stores of energy. They can be broken down more readily than other, more complex molecules for a quick source of usable energy. The process by which usable energy is released from carbohydrates and captured in the bonds of ATP (adenosine triphosphate) for use by cells is known as cellular respiration. Many metabolic processes in cells require energy derived from ATP, so ATP is considered to be the “universal energy currency” of the cell.
All energy pathways can be traced back to sunlight and photosynthesis. For example, the trophic levels of the food chain are integrally linked to