Photosynthesis, essential for life on Earth, is the biological process whereby green plants, algae, and certain protists and bacteria convert light energy into chemical energy. Green pigments, called chlorophylls, absorb the light energy, which is incorporated into the molecular structure of simple sugars. This process produces a wide range of organic compounds, mostly simple sugars, known as monosaccharides,
such as glucose. The simple sugars provide the basic materials for the synthesis of more complex carbohydrates, fats, and amino acids. Amino acids can, in turn, be synthesized into proteins.
The raw materials required for photosynthesis are light energy, water, and carbon dioxide. The synthesis of one molecule of simple sugar is represented in the following equation:
All living cells require a continuous supply of energy in order to carry on their life-sustaining functions. Cellular respiration, the release of energy stored in food, occurs in the mitochondria of a cell. The energy of carbohydrates, such as glucose, is converted to that of ATP (adenosine triphosphate), the common carrier of chemical energy in the cell. Cells use this energy to perform numerous tasks, including
moving substances across the cell membrane and breaking down compounds within the cell.
Yeasts are tiny, unicellular fungi that live on the surfaces of fruits and grains and in areas where sugars are plentiful. Yeast cells can produce energy by either aerobic or anaerobic respiration, also known as fermentation. The type of respiration utilized depends on the environmental conditions. If oxygen and sugars are available and the temperature is suitable (37° to 45°C), aerobic respiration will take place. If oxygen is absent, anaerobic respiration will take place. The end products of these two processes differ. Aerobic respiration in yeast results in the breakdown of sugar molecules into carbon dioxide and water, as shown in the following simplified equation:
In anaerobic respiration, or fermentation, yeast breaks down sugars into carbon dioxide and alcohol, as shown in the following equation:
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Photosynthesis and Cell Respiration Lab Activity
Study the interdependence of cellular respiration and photosynthesis in living organisms by assessing the rate of photosynthesis in elodea and cellular respiration of yeast cells. This activity fulfills a standard investigation in biology textbooks.- Photosynthesis Lab Activity
Choose just how in-depth you’d like to go with photosynthesis studies, with a two-part activity that explores different aspects of the complex process.The first part of the activity focuses on the Hill Reaction, as students carry out partial photosynthesis in the lab by splitting water. In the second part of the activity, students obtain the enzyme phosphorylase and use it to catalyze the synthesis of starch. - Photosynthesis Demonstration Model
Easily demonstrate quantitative examples of photosynthesis and various environmental effects on plants with WARD’S photosynthesis apparatus. The variety of suggested experiments work with either aquatic plants or terrestrial plants. You can change the variables affecting photosynthesis and measure the rate of oxygen emitted as a byproduct, or test the influence of light intensity and wavelength, carbon dioxide and oxygen concentration in water, and other environmental factors. 
AP Biology Lab 4: Plant Pigments and Photosynthesis Lab Activity
With a thorough overview of photosynthesis, chromatography, and spectrophotometry, this comprehensive lab activity helps students perform all the required investigations on plant pigments and photosynthesis. In the process, students learn the principles of chromatography, calculate Rƒ values, and carry out experiments that show how light intensity, light wavelength, and temperature affect the rate of photosynthesis. After learning the proper procedure for extracting chloroplasts from spinach leaves, students separate plant pigments with paper chromatography and study the pigments’ relation to photosynthesis. In addition, they measure the rate of photosynthesis in isolated chloroplasts using a unique method that involves the reduction of the dye DPIP (2,6-dichloroindophenol). The change in color from blue to clear, effected by the transfer of electrons, is measured with a spectrophotometer, available separately.
