Question

A group of students wants to study the rate of photosynthesis under various conditions. They use a blender to mechanically disrupt the thylakoid membranes of chloroplasts from an algae sample The liquid
mixture is added to test-tubes, and 5 drops of DPIP solution is added to each tube. One set of tubes is placed in direct sunlight, another is placed in indirect sunlight, and a third is placed under an infrared heat
lamp. One test-tube contains only water and 5 drops of DPIP (control). The students check the color of the liquid in the tubes every 15 minutes for a period of 1 hour. They record their observations in a table
Table of Observations
Time (min) Direct Sunlight
Indirect Sunlight
0
Dark Blue
Dark Blue
15
Lighter
Slightly Lighter
30
Lighter
Lighter
45
Nearly colorless
Lighter
60
Clear colorless
Nearly colorless
Which of the statements is the BEST explanation for their results?
Infrared Lamp
Dark Blue
No Change
Slightly Lighter
Slightly Lighter
Slightly Lighter
Control
Dark Blue
Dark Blue
Dark Blue
Dark Blue
Dark Blue
А
The rate of photosynthesis under indirect sunlight is slower than in infrared light
B
The rate of photosynthesis is greatest for direct sunlight and least for the infrared light.
С
The rate of photosynthesis cannot be determined because the infrared lamp degraded the DPIP
D
The rate of photosynthesis cannot be determined because exposure to direct sunlight degraded the DPIP

Answer 1

Answer:

B

Explanation:

The statement that best explains the result would be that the rate of photosynthesis is greatest for direct sunlight and least for the infrared light.

The DPIP will normally replace and play the role of NADPH in the light reaction of the process of photosynthesis. Hence, it will become colorless as a result of reduction and the rate of photosynthesis can be monitored based on the magnitude of the disappearance of the dark blue color.

It means that the more colorless the liquid in the illustration is, the more the rate of photosynthesis. The color change moved from dark blue to clear colorless under direct sunlight, from dark blue to nearly colorless under indirect sunlight, and from dark blue to slightly lighter under the infrared light. This clearly indicates that the rate of photosynthesis is highest under direct sunlight and lowest under infrared light with the indirect sunlight having an intermediate rate.

The correct option is B.