Biology 12

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Relative light absorption

Wavelength (nm)

chlorophyll b

chlorophyll a

MINI LAB

Photosynthetic Pigments

In this lab you will investigate the colours of chlorophylls,
the photosynthetic pigments found in many plants. You will
need to produce a concentrated extract of chlorophylls.

The materials you will require are: 15 g fresh or frozen
spinach, 50 mL isopropyl alcohol, food blender, 100 mL
beaker, funnel, filter paper, strong light source (for example,
slide projector).

Using the food blender, grind the spinach with 50 mL of
isopropyl alcohol. Filter the extract through several layers
of filter paper in the funnel. Then, in a darkened room, shine
a strong beam of light at a sample of the filtered extract.
Observe the colour of the chlorophylls by viewing the
sample at a slight angle and then at a right angle to the
beam of light. Describe the appearance of the chlorophylls
as viewed from both angles.

Analyze

1.What colours of the visible light spectrum are absorbed

by chlorophyll as part of the photoreaction?

2.What wavelengths of visible light are absorbed by the

chloroplasts?

3.When you viewed the solution, the effect you saw is

called fluorescence. What colours and wavelengths

were produced?

Photosynthetic pigments

Chapter 3 Cellular Energy • MHR 85

visible spectrum

prism

white light solution of

chlorophyll

yellow and green

transmitted

Figure 3.22The relative absorption of light by chlorophylls aand b.

Visible light represents only

a small segment of the

electromagnetic spectrum.

A

Chlorophylls aand b

absorb certain

wavelengths of

visible light.

B