- Sunglight is a form of electromagnetic energy, which travels in waves
- Different forms of electromagnetic energy have characteristic wavelengths
- Visible light makes up only a small fraction of the electromagnetic spectrum
- Wavelenghts that are shorter than those of visible light have enough energy to damage organic molecules
- A substance's color is due to pigments
- When light shines on a material that contains pigment it can be absorbed, transmitted, or reflected, which depends on the wavelengths
- Chloroplast convert some absorbed light into chemial energy
- Chloroplast don't absorb green light
- We could observe the different pigments in a green leaf by using paper chromatography
- Within the thylakoid membrane, chlorophyll and other molecules are arranged in photosystems
- Whenever a pigment molecule absorbs light energy, one of the pigment's electrons gains energy
- That electron will falls back to the ground state and transgers the energy to a neighboring molecule immediately
- The energy transfers between molecules and arrives at the reactin center of the photosystem, which includes a primary electron acceptor
- The light reactions involve two phtosystems connected by an electron transport chain
- Respiration food provides the electrons for the electron transport chain of light reaction
- The second photosystem is NADPH producing photosystem
- The light reactions convert light energy to the chemical energy of ATP and NADPH
Vocabulary:
- wavelength - distance between adjacent waves
- electromagnetic spectrum - range of types of electromagnetic energy from gamma waves to radio waves
- pigment - chemical compound that determines a substance's color
- paper chromatography - laboratory technique used to observe the different pigments in a material
- photosystem - cluster of chlorophyll and other molecules in a thylakoid
Concept Check:
- A leaf appears green because green light is not absorbed and being reflected.
- ATP and NADPH
- It takes place in the thylakoid membrane
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