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Science · Drill 38

Science practice 38

9 questions ~9 min recommended
⏱ 00:00
Score
—

90
80
70
60
50
40
30
20
10
400
-10 -
Relative Absorbances of Plant Pigments
- Chlorophyll a
Chlorophyll b
- - Carotenoids
450
500
550
600
Wavelengths of light (nm)123456789|
650
700

Color
Red
Orange
Yellow
Green
Blue
Violet
Wavelength
620-750 nm
590-620 nm
570-590 nm
495-570 nm
450-495 nm
380-450 nm

Photosynthesis is the process by which organisms such as green plants, algae, and cyanobacteria convert light energy from the sun to chemical energy stored in the bonds of carbohydrates. Chlorophyll is a pigment employed by many autotrophic organisms to absorb the various wavelengths of visible light from the sun for use in photosynthesis. A variety of photosynthetic pigments exist; they are specifically adapted for absorbing different ranges of the visible light spectrum and reflecting others. The absorption spectrum of chlorophyll and accessory pigments can be obtained through spectrophotometry and later used to gain insight into plant growth, determine the abundance of photosynthetic organisms in fresh- or saltwater, and evaluate water quality.

The data in Figure 11.1 and Table 11.2 were collected by students measuring the absorption spectra of three commonly encountered photosynthetic pigments.

Figure 11.1

TABLE 11.2

1. Which of the following statements represents a valid assessment of the data?

2. Using the information in Table 11.2, which of the following wavelengths of light would phycocyanin, a pale blue-colored accessory pigment, reflect most?

3. Based on Figure 11.1, which of the following wavelengths of visible light would be absorbed to promote the most photosynthetic activity in green plants?

4. Based on the information in Figure 11.1 and Table 11.2, which pigment has the highest relative absorbance in the red portion of the spectrum?

5. Which of the following statements about the relative absorbance levels of the pigments is most accurate?

6. Which pigment would absorb the most violet light at a wavelength of 425 nm?

7. Which wavelength represents the maximum absorbance of chlorophyll b?

8. From the information in the passage, one can conclude that chlorophyll appears green to the human eye because:

9. Phycoerythrin is a photosynthetic pigment that is found in marine algae. It has absorption peaks at 495 nm and 566 nm and reaches its lowest values over 600 nm. Based on this information, one would expect phycoerythrin to:

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