Chlorophyll is a substance that is present in specialized cells within plants and many algae. When sunlight is present, chlorophyll combines it with water and carbon dioxide and creates energy through this process of photosynthesis. Organisms that can photosynthesize are known as autotrophs, which literally means "self feeder."
Chlorophyll is a pigment that is vital in the process of photosynthesis. Cells, called chloroplasts, within leaves contain the chlorophyll. When sunlight is absorbed by the plant, it strikes these cells and the chlorophyll produces nutrients as well as energy for plants to carry out functions such as growth and reproduction.
There are several types of chlorophyll, including chlorophyll a, chlorophyll b, chlorophyll c1, chlorophyll c2 and chlorophyll d. The presence of these different chlorophyll molecules depends on which group of plants or algae you are considering. Chlorophyll a is found in plants and algae, while chlorophyll b is found only in plants. The other chlorophyll molecules (c1, c2 and d) are found in different types of algae.
Each chlorophyll molecule absorbs a slightly different wavelength of light, so that one organism possessing two different types of chlorophyll molecules can take advantage of a greater number of wavelengths than organisms having only one chlorophyll type.
Chlorophyll appears green because it reflects green light. If an object reflects light of one color, it is absorbing different wavelengths of light. So chlorophyll reflects green light as it absorbs green and blue wavelengths of light. Exposing a chlorophyll-containing plant to only green light, therefore, would result in little to no photosynthesis, because it will be absorbing no light. Plants grown in blue or red lights, conversely, will photosynthesize and grow well.
Typically plants will possess more than one type of pigment in order to take advantage of a greater number of wavelengths of light. Other pigments, such as xanthophylls and caratenoids, are purple or yellow, and because they reflect those colors, will readily absorb the green light that the dominant chlorophylls are reflecting.
Chlorophyll is thought by some to be a healthy supplement, because chlorophyll is the pigment that makes green plants green. It is said to detoxify the liver and blood, as well as cleanse the digestive system and act as a powerful antioxidant. Supplements can be purchased at health food stores.
Plant food is only a fertilizer that provides plants with nutrients that may otherwise be lacking in the soil. Since plants are autotrophic, they technically make their own food, so there really is no such thing as supplemental plant food.