Question

In a lab students are learning about absorption spectroscopy, which is a technique used to measure the absorption of radiation by a sample. The sample will absorb energy (i.e. photons) from the radiating field. In terms of pigments found in pants, optimal absorption of light will occur at different wavelengths for each pigment. The set of optimal wavelengths absorbed by pigments is known as an absorption spectrum. In the lab, the students are given an unknown pigment and are tasked with determining its absorption spectrum. The student’s data can be found below.

a) Identify three pigments commonly found in plants and briefly describe the role of each.

Answer 1

The three common pigments in plants are chlorophyll a, chlorophyll b, and carotenoids, each absorbing different wavelengths of light and playing specific roles in photosynthesis and photoprotection.

Step-by-step explanation:

Three common pigments found in plants are chlorophyll a, chlorophyll b, and carotenoids. Chlorophyll a is essential for the process of photosynthesis as it absorbs light primarily in the blue and red wavelengths, and is central to the conversion of solar energy to chemical energy. Chlorophyll b, which also participates in photosynthesis, absorbs light in the blue and red-orange wavelengths and complements the absorption spectrum of chlorophyll a. Carotenoids are a diverse group that serves multiple roles, including photoprotection by absorbing excessive light and contributing to the capture of light due to their absorption in the blue region of the spectrum.

Answer 2

Chlorophyll a is the main photosynthetic pigment, chlorophyll b assists by expanding the light absorption range, and carotenoids protect chlorophyll and give certain plants their color. Their unique absorption spectra are used for identification.

Step-by-step explanation:

Three pigments commonly found in plants are chlorophyll a, chlorophyll b, and carotenoids. Chlorophyll a is the primary pigment in plants and is responsible for absorbing light mostly in the blue-violet and red wavelengths, playing a central role in photosynthesis by converting light energy into chemical energy. Chlorophyll b assists chlorophyll a by extending the range of light that can be absorbed, capturing additional wavelengths in the blue and red-orange parts of the spectrum.

Carotenoids, such as β-carotene, absorb light in the blue-green region and help in photosynthesis by protecting the chlorophyll from damage caused by excess light. Their ability to reflect longer yellow, red, and orange wavelengths is also what gives many fruits and flowers their distinctive colors.

Their absorption spectrum is the footprint, each with a unique pattern of wavelengths absorbed which is used to identify the types of pigments present in a plant. By measuring the absorption of different wavelengths using a spectrophotometer, we can deduce the presence and concentration of these pigments.