Photosynthesis is dependent on light- harvesting molecules called pigments. The
ID: 189935 • Letter: P
Question
Photosynthesis is dependent on light- harvesting molecules called pigments. The most abundant and important pigments in most leaves are chlorophylls a and b Chlorophyll pigments predominantly absorb blue and red light, and reflect green light - this is why leaves appear green. Other pigments are present in leaves, but they are best seen in autumn when chlorophylls degrade, and the brilliant reds, yellows, and oranges of the other pigments remain to color leaves. Paper chromatography is a common technique used in chemistry to separate mixtures of different molecules. We will use chromatography to see different light- capturing pigments in spinach leaves. chlorophyll b chlorophyll a 400 500 600 700 Wavelength [nm] Figure 4. Absorbance spectra of chlorophylls a and b in a solvent How might you use the spectrophotometer to find out the wavelengths of light at which 1 p pigments from leaves absorbs light energy?Explanation / Answer
The absorption spectrum displays the wavelength of radiation absorbed by photosynthetic pigments in plant leaves. Chlorophyll a has two absorption peaks. It can absorb in blue light and red light. Similarly, chlorphyll b has two peaks.
The spectrophotometer is an instrument used to measure the absorption maxima or concentration of a given sample. In this, a sample is taken in a transparent cuvette and lights of various wavelengths are passed through it. Every time, the transmitted light is analyzed to observe where the given compound has maximum absorption maxima.