Question

A controlled experiment was conducted to analyze the effects of darkness and boiling on the photosynthetic rate of incubated chloroplast suspensions. The dye reduction technique was used. Each chloroplast suspension was mixed with DPIP, an electron acceptor that changes from blue to clear when it is reduced. Each sample was placed individually in a spectrophotometer and the percent transmittance was recorded. The three samples used were prepared as follows.

Sample 1 – chloroplast suspension + DPIP

Sample 2 – chloroplast suspension surrounded by foil wrap to provide a dark environment + DPIP

Sample 3 – chloroplast suspension that has been boiled + DPIP


On the axes provided, construct and label a graph showing the results for the three samples.

Answer 1

Answer:

In sample 1, color of the dye changed from blue to clear.

In sample 2, color of the dye remained intact.

In sample 3 color of the dye remains intact.

Explanation:

1. Photosynthesis occurs thus the color of the dye changes from blue to colorless.
2. If the tube is covered with foil, it prevents light from reaching the chloroplasts floating inside the tube. Since the chlorophyll molecule does not receive light, electrons do not pass through her ETC, water is not photolyzed and therefore NADP (here his DPIP) is not reduced. As such, the compound color remains the same throughout the experiment.
3. With heated chloroplasts and light, photosynthesis will not occur. Boiling the chloroplasts ruptures and destroys them, halting the process of photosynthesis. Light is important for the process of photosynthesis. Light striking photosystem II is responsible for binding excited electrons to NADP, but in this experiment the compound DPIP is used as a proxy to determine the transmittance. Without the presence of chloroplast DPIP won't get reduced to DPIPH, thus the color remains intact.

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Answer 2

A controlled experiment was conducted to analyze the effects of darkness and boiling on the photosynthetic rate of incubated chloroplast suspensions. The dye reduction technique was used. Each chloroplast suspension was mixed with DPIP, an electron acceptor that changes from blue to clear when it is reduced. Each sample was placed individually in a spectrophotometer and the percent transmittance was recorded.

• This controlled experiment was conducted to study the effects of darkness and boiling on the photosynthetic rate of incubated chloroplast suspensions.
• The photosynthetic rate was measured using the dye reduction technique, which involves adding an electron acceptor (DPIP) that changes from blue to clear when it is reduced. Three samples were prepared for the experiment:

• Sample 1: This sample consisted of a chloroplast suspension mixed with DPIP.
• Sample 2: This sample was prepared by surrounding a chloroplast suspension with foil wrap to create a dark environment, and then adding DPIP.

• Sample 3: This sample was prepared by boiling a chloroplast suspension and then adding DPIP.

• Each sample was placed in a spectrophotometer and the percent transmittance was recorded.
• The results of the experiment will likely show how the photosynthetic rate of the chloroplast suspensions is affected by the different conditions (darkness and boiling).

Thus, the results of the experiment will likely show how the photosynthetic rate of the chloroplast suspensions is affected by the different conditions (darkness and boiling).

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