Question

1. What is the source of carbon for photosynthesis in plants? A. Carbonic acid B. Carbon monoxide C. Carbon Dioxide D. Calcium carbonate 2. H2CO3 forms when CO2 mixes with water. Why does it change the phenol red indicator to yellow? A. It is sodium carbonate, the color change shows a salt has formed. B. It is iron carbonate, it dissolves and releases iron which oxidizes (rusts). C. It is barium carbonate, which is naturally a dark yellow color. D. It is carbonic acid, so it has a low pH. 3. What gas would you see forming bubbles on the Elodea when it is placed under bright lights? A. Hydrogen B. Oxygen C. Carbon Dioxide D. Carbon Monoxide 4. We use a paper chromatography technique that separates the leaf pigments dissolved in a solvent based on the pigments': A. Weight B. Charge C. Color D. Size 5. We use iodine to detect the presence of in specific sections of the Coleus leaf, which provides evidence of photosynthesis.

Answer 1

Answer 1. C. Carbon dioxide. During the process of photosynthesis, a cascade of enzymatic reactions fix carbon to form organic compounds also called dark reaction of photosynthesis.

Answer 2. D. It is carbonic acid, so it has a low pH. Phenol red indicator is an organic dye which changes its color based on the pH of the solution. If it turns yellow when added to the solution, it indicates low pH i.e. acidic solution.

Answer 3. B. Oxygen. Elodea is a freshwater green plant used to carry out lab experiments for CO2 consumption during photosynthesis. During the photosynthesis process, carbon dioxide is fixed in the presence of sunlight to form glucose and oxygen. The rate of photosynthesis depends on carbon dioxide and sunlight. So, when elodea is kept under bright light, photosynthesis will be rapid depending upon carbon availability; thus oxygen release will be more.

Answer 4. C. color. Paper chromatography technique used to separate pigments present on the leaves. This technique depends on the solubility of the pigment, the dye that is most soluble travels the most distance on the paper. However, the least soluble pigment will move the least distance on the paper. This process helps us to separate the pigments based on the color that appears at the point where pigments reach.

Answer 5. Starch. Iodine is a well-known indicator used in several experiments to detect the presence of starch. Since photosynthesis products are stored in the form of starch, as evidence, the presence of starch will surely confirm the photosynthetic process has occurred. If upon addition of iodine, a blue-black color appears, it indicates that starch is present.