Question

question 27
identify the purpose of each of the following steps in the photosynthesis experiment.
hole - punching the leaves
adding bicarbonate buffer to the syringe.
exposing the disks to a vacuum in the syringe
adding a plain buffer to the syringe

Explanation:

• Hole - punching the leaves: This step is to standardize the surface area of the leaves. By creating uniform leaf disks, it ensures that each sample has a similar area for consistent photosynthetic activity measurement.
• Adding bicarbonate buffer to the syringe: Bicarbonate buffer provides a source of water and carbon dioxide. Carbon dioxide is an essential reactant for photosynthesis, and the buffer helps maintain a stable supply.
• Exposing the disks to a vacuum in the syringe: This removes air (including oxygen) from the leaves. Removing oxygen makes the leaves sink as they lose buoyancy from the gas spaces, and it also helps in creating a controlled environment to observe the effects of photosynthesis (as oxygen will be produced later during photosynthesis and can cause the leaves to float again).
• Adding a plain buffer to the syringe: A plain buffer provides a source of water only (no carbon dioxide). It can be used as a control in the experiment, where the lack of carbon dioxide (a key photosynthesis reactant) allows comparison with the bicarbonate - containing solution.

Answer:

• Hole - punching the leaves: standardize the surface area of the leaves
• Adding bicarbonate buffer to the syringe: provide a source of water and carbon dioxide
• Exposing the disks to a vacuum in the syringe: remove oxygen from the leaves to make them sink
• Adding a plain buffer to the syringe: provide a source of water only (no carbon dioxide)