TLC of plant pigments

• What is the main objective of the lesson on photosynthetic pigments?

  To identify photosynthetic pigments found in leaves of different plants
• How can photosynthetic pigments be extracted from leaves?

  By using chromatography
• What technique can be used to separate biological compounds?

  Thin layer chromatography or electrophoresis
• What is the formula to calculate Rf values in chromatography?

  Rf = y/x
• What does 'y' represent in the Rf value formula?

  The distance travelled by the pigment from the bottom pencil line to each spot
• What does 'x' represent in the Rf value formula?

  The distance travelled by the solvent from the bottom pencil line to the solvent front
• What is the advantage of having several different pigments in plants?

  It ensures the optimum use of light energy
• Why is it better to use an Rf value rather than the actual distance moved by a compound on the chromatogram?

  Because Rf values are standardized and allow for comparison
• What should a student use to mark the origin on a chromatography paper?

  Pencil
• Why should a student use pencil to mark the origin in chromatography?

  Because ink may dissolve and interfere with the results
• Describe the method used to separate pigments after applying the solution to the origin.

  The student placed the chromatography paper in a solvent and allowed it to rise
• What is the advantage of having different colored pigments in leaves?

  It allows plants to absorb a wider range of light wavelengths
• What physical properties are used to separate molecules in chromatography?

  Solubility and size
• How can colorless molecules be detected on a chromatogram?

  By using UV light or chemical stains
• What technique can be used to make spots on a chromatogram spread out further?

  Increase the solvent volume or change the solvent composition
• What is the significance of chlorophyll containing several different pigments?

  It enhances the plant's ability to capture light energy for photosynthesis