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In biology, phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism occurs. This causes the plant to have ...
Photobiology is the scientific study of the beneficial and harmful interactions of light (technically, non-ionizing radiation) in living organisms. [1] The field includes the study of photophysics, photochemistry, photosynthesis, photomorphogenesis, visual processing, circadian rhythms, photomovement, bioluminescence, and ultraviolet radiation effects.
The light-harvesting system of PSI uses multiple copies of the same transmembrane proteins used by PSII. The energy of absorbed light (in the form of delocalized, high-energy electrons) is funneled into the reaction center, where it excites special chlorophyll molecules (P700, with maximum light absorption at 700 nm) to a higher energy level.
Oat phytochrome absorption spectrum (Devlin, 1969). Phytochromes are a class of photoreceptor proteins found in plants, bacteria and fungi.They respond to light in the red and far-red regions of the visible spectrum and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. [2]
In biology, a tropism is a phenomenon indicating the growth or turning movement of an organism, usually a plant, in response to an environmental stimulus. [1] In tropisms, this response is dependent on the direction of the stimulus (as opposed to nastic movements , which are non-directional responses).
Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight.Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stress caused by excess or fluctuating light conditions.
Other larvae show negative phototaxis by swimming away from the light. First, the light comes from left and then from the right side. When the light direction is switched the larvae turn. The side where the light is coming from is indicated by a white bar. The larvae display mixed phototaxis, some negatively phototactic larvae are tracked.
At the heart of a photosystem lies the reaction center, which is an enzyme that uses light to reduce and oxidize molecules (give off and take up electrons). This reaction center is surrounded by light-harvesting complexes that enhance the absorption of light. In addition, surrounding the reaction center are pigments which will absorb light. The ...