common Q&A

• What is the purpose of boiling the leaf in water?

  To stop all chemical processes in the leaf.
• What does a blue-black color indicate when iodine solution is added to a leaf?

  The presence of starch, showing that photosynthesis has occurred.
• Why is it necessary to destarch the plant before the experiment?

  To ensure any starch found is a result of the current experiment.
• What conclusion can you draw if only the parts of the leaf exposed to sunlight turn blue-black?

  Sunlight is necessary for photosynthesis.
• Why do only the green parts of a variegated leaf turn blue-black with iodine solution?

  Only green parts contain chlorophyll, which is essential for photosynthesis.
• Why is a plant enclosed with soda lime not able to produce starch?

  Soda lime absorbs CO₂, which is necessary for photosynthesis.
• What gas is produced by aquatic plants during photosynthesis, and how can it be tested?

  Oxygen is produced, and it can be tested using a glowing splint which reignites in the presence of oxygen
• What happens to the leaf when it is placed in alcohol?

  The leaf becomes decolorized as the alcohol removes the chlorophyll, making it easier to see the color change with iodine.
• Why is it important to soften the leaf after decolorizing it with alcohol?

  Softening the leaf makes it more permeable to the iodine solution.
• Photosynthesis investigation

  1. Place a leaf between two pieces of black paper

  2. Expose to strong sunlight

  3. Test for starch in regions that are parts exposed to sunlight
• What does the black paper experiment demonstrate?

  It demonstrates that the parts of the leaf exposed to sunlight can perform photosynthesis and produce starch, while the covered parts cannot.

  
• What role does sunlight play in photosynthesis?

  Sunlight provides the energy needed for the photosynthetic process to convert carbon dioxide and water into glucose and oxygen.
• What would you observe if chlorophyll were not necessary for photosynthesis?

  If chlorophyll were not necessary, both green and white parts of the leaf would show the presence of starch.
• Why is a control setup important in experiments involving plants?

  A control setup provides a basis for comparison, ensuring that the results are due to the experimental variable and not other factors.
• What conclusion can be drawn if the plant exposed to normal air shows starch production while the one in the jar with soda lime does not?

  Carbon dioxide is necessary for photosynthesis.
• Why is sodium hydrogen carbonate used in the experiment with aquatic plants?

  Sodium hydrogen carbonate provides a source of carbon dioxide for the aquatic plants.
• What does the formation of bubbles on the leaves indicate?

  The formation of bubbles indicates that oxygen is being produced as a byproduct of photosynthesis.
• What are the main external factors that affect the rate of photosynthesis?

  Light intensity, carbon dioxide concentration, and temperature.
• How does light intensity affect the rate of photosynthesis?

  Initially, as light intensity increases, the rate of photosynthesis increases until it reaches a plateau where another factor becomes limiting.
• What happens to the rate of photosynthesis when carbon dioxide concentration is increased?

  The rate of photosynthesis increases with higher carbon dioxide concentration until another factor becomes limiting.
• Why does temperature affect the rate of photosynthesis?

  Photosynthesis is an enzyme-driven process, and enzymes work more efficiently at optimal temperatures. Extreme temperatures can slow down or halt the process.
• What is the overall equation for photosynthesis?

  6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
• Why is photosynthesis important for the environment?

  Photosynthesis removes carbon dioxide from the atmosphere and produces oxygen, which is essential for the survival of most living organisms.
• What is the role of chlorophyll in photosynthesis?

  Chlorophyll absorbs light energy, which is used to convert carbon dioxide and water into glucose and oxygen.
• What happens to the glucose produced during photosynthesis?

  Glucose can be used immediately for energy, converted into starch for storage, or used to form other organic compounds like cellulose and proteins.