CLT Photobiology & Light Science 1 — Questions and Answers
Question 1: What is the term for the study of the effects of light on living organisms?
- Photobiology (Correct answer)
- Photometry
- Radiometry
- Spectroscopy
Correct answer: Photobiology
Photobiology is the scientific discipline that examines how light affects living organisms at cellular and systemic levels.
Question 2: Which part of the electromagnetic spectrum is used in most light therapy applications?
- Visible and near-infrared light (Correct answer)
- X-rays and gamma rays
- Microwaves and radio waves
- Far-ultraviolet radiation
Correct answer: Visible and near-infrared light
Visible and near-infrared light (400–1100 nm) are the ranges most commonly used in light therapy due to their safe and therapeutic tissue penetration.
Question 3: What is the Grotthuss-Draper Law in the context of light therapy?
- Only absorbed light can produce photochemical effects (Correct answer)
- Light travels in straight lines through tissue
- Longer wavelengths penetrate deeper than shorter wavelengths
- Photons must exceed a threshold intensity to be effective
Correct answer: Only absorbed light can produce photochemical effects
The Grotthuss-Draper Law states that only light that is absorbed by a chromophore can initiate a photochemical reaction.
Question 4: Which cellular organelle is considered the primary chromophore for red and near-infrared light therapy?
- Cytochrome c oxidase in mitochondria (Correct answer)
- Nucleus
- Golgi apparatus
- Lysosome
Correct answer: Cytochrome c oxidase in mitochondria
Cytochrome c oxidase, located in the mitochondrial inner membrane, is the main chromophore that absorbs red and near-infrared light to enhance ATP production.
Question 5: What does the term 'fluence' refer to in light therapy dosimetry?
- Total energy delivered per unit area (J/cm²) (Correct answer)
- Number of photons emitted per second
- The wavelength range of the light source
- The angle of light incidence on tissue
Correct answer: Total energy delivered per unit area (J/cm²)
Fluence, measured in joules per square centimeter (J/cm²), represents the total radiant energy delivered to a surface area during a treatment.
Question 6: Which principle describes the biphasic dose-response relationship in photobiomodulation?
- Arndt-Schulz Law (Correct answer)
- Beer-Lambert Law
- Bunsen-Roscoe Law
- Fick's Law
Correct answer: Arndt-Schulz Law
The Arndt-Schulz Law describes how low doses stimulate, moderate doses have no effect, and high doses inhibit biological processes.
CLT Photobiology & Light Science 1
What is the term for the study of the effects of light on living organisms?