Photosynthesis is a biological process by which energy in light is converted into chemical energy of bonds between atoms that power processes within cells. Photosynthesis emerged roughly 3.5 billion years ago in geological history and occurs today within a variety of single-celled organisms as well as in plants. Earth's atmosphere and seas contain oxygen because of photosynthesis.
Photosynthesis Consists of Light and Dark Reactions
Photosynthesis takes places over a series of physical and chemical mechanisms divided into two phases: the light reactions and the dark reactions. During the light reactions of photosynthesis, light from the sun is captured through a series of reactions involving the chemical chlorophyll. This results in the synthesis of two high-energy chemical compounds: ATP and NADPH, whose chemical energy is held by electrons that can be transferred easily to other compounds. The light reactions require water (H2O), from which oxygen is released during the process. ATP and NADPH are used subsequently to produce glucose from CO2 in the next phase of photosynthesis, the dark reactions.
The Light Reactions of Photosynthesis Make Use of Pigments
Pigments are chemicals which reflect certain wavelengths (colors) of light but not others. Different pigments reflecting different wavelengths give flowers a variety of colors. Additionally, seasonal changes in the relative synthesis of different pigments accounts for color changes in leaves during the autumn.
Green Light is the Least-Effective Color of Light in Driving Photosynthesis
Pigments are vital components of the machinery of photosynthesis, the most important pigment being chlorophyll. Chlorophyll is a big molecule which captures energy from sunlight and converts it to high-energy electrons. This happens during the light reactions of photosynthesis. Pigments other than chlorophyll include carotenoids (which are red, yellow and orange) and phycobilins. Phycobilins include phycocyanin, which imparts a bluish color to blue-green algae (also known as cynanobacteria), and phycoerythrin, which gives a reddish color to red algae.
A pigment imparts a specific color to a plant by reflecting a particular wavelength, or color of light. When a certain color of light is reflected, it is not absorbed to energize a pigment to drive photosynthesis. Since chlorophyll is the most important pigment and reflects, and therefore does not utilize, green light, green is the color of light that is least effective in driving the photosynthetic process.
How Does Light Color Affect Photosynthesis?
Photosynthesis comes from the Greek words “light” and “putting together.” During photosynthesis, plants absorb light energy and use it to make molecules...
What Color of Light Do Plants Absorb?
White light contains various colors, including red, orange, yellow, green, blue, indigo and violet. When plants harvest light for photosynthesis, they only...
The Effect of Color Filters in Photosynthesis
Measuring the effects of light color on photosynthesis is a fun and simple experiment for middle or high school students. By growing...