Absorption Spectrum

Definition

An absorption spectrum is a graphical representation that shows the specific wavelengths of light absorbed by a substance, such as photosynthetic pigments. It reveals how different pigments absorb light energy, which is crucial for the process of photosynthesis. By understanding the absorption spectrum, one can determine which wavelengths are most effective for driving photosynthesis in plants.

5 Must Know Facts For Your Next Test

1. The absorption spectrum of chlorophyll shows peaks primarily in the blue (around 430 nm) and red (around 660 nm) regions, while it has lower absorption in the green region, explaining why plants appear green.
2. Different pigments have unique absorption spectra, allowing plants to capture a broader range of light wavelengths for photosynthesis.
3. The absorption spectrum can be obtained through spectrophotometric techniques, which analyze how much light is absorbed by pigments at various wavelengths.
4. Understanding the absorption spectrum helps researchers optimize light conditions for plant growth and can inform agricultural practices.
5. Absorption spectra play a role in determining how light intensity and quality affect photosynthetic efficiency in different plant species.

Review Questions

• How do absorption spectra differ among various photosynthetic pigments, and what implications does this have for photosynthesis?
  • Absorption spectra vary among different photosynthetic pigments like chlorophyll a, chlorophyll b, and carotenoids. Each pigment absorbs specific wavelengths of light more effectively, which allows plants to utilize a wider range of the light spectrum. This diversity in absorption enables plants to maximize energy capture from sunlight, improving their overall efficiency in photosynthesis.
• Explain how spectrophotometry is used to determine the absorption spectrum of plant pigments and its significance in studying plant physiology.
  • Spectrophotometry is employed to quantify the amount of light absorbed by plant pigments across various wavelengths. By shining light through a pigment solution and measuring the intensity of transmitted light at each wavelength, researchers can construct an absorption spectrum. This data is significant as it allows scientists to assess which wavelengths are most effective for photosynthesis and how different environmental conditions may affect pigment functionality.
• Analyze the relationship between an organism's absorption spectrum and its habitat adaptations, focusing on how this impacts its survival.
  • The absorption spectrum of an organism's pigments directly influences its ability to perform photosynthesis effectively in its specific habitat. For example, plants in shaded environments may evolve to have pigments that absorb light more efficiently in the lower light conditions found under canopy cover. This adaptation helps them maximize light capture and energy production, enhancing their survival and competitiveness in less favorable conditions where sunlight is limited.

Related terms

Photosynthesis:

The process by which green plants and some other organisms convert light energy into chemical energy in the form of glucose, using carbon dioxide and water.

Chlorophyll: The main pigment found in plants that absorbs light for photosynthesis, primarily in the blue and red wavelengths.

Spectrophotometry: A method used to measure the amount of light absorbed by a sample at different wavelengths, providing information about the absorption spectrum of the material.