photosynthesis in leaf disks lab answer key

The photosynthesis in leaf disks lab involves using leaf disks, sodium bicarbonate solution, and light to observe the process of photosynthesis in action. Here are the steps and expected results for the lab:

Materials:

• Spinach leaves
• Syringe
• Sodium bicarbonate solution
• Light source
• Stopwatch
• Water

Procedure:

1. Cut several small disks from the spinach leaves using a hole puncher.
2. Fill a syringe with sodium bicarbonate solution.
3. Place the leaf disks in a beaker with water and add the sodium bicarbonate solution.
4. Place the beaker under a light source and start the stopwatch.
5. Observe the leaf disks and record the time it takes for them to rise to the top of the beaker.

Expected Results:

• Initially, the leaf disks will sink to the bottom of the beaker due to their high density.
• As photosynthesis occurs, oxygen is produced and the leaf disks become less dense, causing them to rise to the top of the beaker.
• The time it takes for the disks to rise to the top of the beaker will depend on the rate of photosynthesis, which is influenced by the intensity of the light source and the amount of sodium bicarbonate solution present.

Answer key:

1. What is the purpose of the sodium bicarbonate solution?

• The sodium bicarbonate solution provides a source of carbon dioxide, which is needed for photosynthesis to occur.

2. Why do the leaf disks initially sink to the bottom of the beaker?

• The leaf disks initially sink to the bottom of the beaker due to their high density.

3. What happens to the leaf disks as photosynthesis occurs?

• As photosynthesis occurs, oxygen is produced and the leaf disks become less dense, causing them to rise to the top of the beaker.

4. How does the rate of photosynthesis affect the time it takes for the leaf disks to rise to the top of the beaker?

• The rate of photosynthesis affects the time it takes for the leaf disks to rise to the top of the beaker. A faster rate of photosynthesis will result in the disks rising more quickly.

5. How does the amount of sodium bicarbonate solution affect the rate of photosynthesis?

• The amount of sodium bicarbonate solution affects the rate of photosynthesis. A higher concentration of sodium bicarbonate solution will provide more carbon dioxide for photosynthesis, resulting in a faster rate of photosynthesis.