Review of the Literature Light consists of electric and magnetic fields, commonly known as electromagnetic waves.
These waves are generated by the oscillation, movement back and forth of electric charges. The term light is commonly referred to just those electromagnetic waves that we are able to see. Light can only be visible when it has a wavelength within a narrow range of values called the visible spectrum, if the wavelength is too long or short, it is a different kind of wavelength in the electromagnetic spectrum. Visible light has a wavelength between about 300 nanometers and 700 nanometers. Violet light has the shortest wavelength in the visible spectrum, and red light has the longest wavelength; all the other colors in the spectrum have a wavelength between them. Many philosophers questioned the existence of light, some argued that it was a stream of particles, while others argued it was composed of waves.
Sir Isaac Newton performed many experiments on light at the end of the 17th century, but his most significant one was where he showed that white light is made of many colors and each individual color can not be used to recreate white light or broken down further using sunlight and prisms. He also predicted that different colored light has different wavelengths. During the 19th century, James Clerk Maxwell showed that there must be waves of oscillating electric and magnetic fields. These waves were predicted to travel at a speed very close to the measured speed of light, making it likely that visible light is an electromagnetic phenomenon. We now know that light is indeed a high frequency form of electromagnetic radiation.
The wave theory of light seemed successful, Albert Einstein showed in 1905 that in order for the photoelectric effect (where electrons can be knocked out of metals by shining light of high enough frequency) to be correct, it required light to come in discrete packets, or Photons, as Einstein called it. This meant that light could also act as a particle, and the question how light can behave as a particle and as a wave remains a mystery even today. An experiment was done at EPFL that captured an image of light as a wave and as a particle at the same time.
They used electrons to capture the image of light acting as a wave and a particle by shining a laser at a nanowire, the electrons interacted with the photons, creating a quanta, and then a photo was taken through an electron microscope. The human body cannot make much use of sunlight except for sunburn and possibly a little vitamin D, a vitamin synthesized in the skin in the presence of sunlight. However, when plants get hit with sunlight, they utilize it. Through a process called photosynthesis, plants use light energy to make carbohydrates.
Photosynthesis begins in specialized organic molecules called pigments, which are found in the chloroplasts of plant cells. Pigments are chemical compounds that reflect certain wavelengths of the visible spectrum, making them colorful, but more important than their ability to reflect light is their absorption of certain wavelengths. Pigments are useful to anything that uses photosynthesis to make their own food, or autotrophs, but their is usually a need to produce multiple kinds of pigments, each a different color since pigment reacts within a narrow range of the visible spectrum. There are three basic classes of pigments, chlorophyll(chlorophyll a and b), carotenoids, and phycobilins.
There are five types of chlorophylls, chlorophyll a and b being the most important. Chlorophylls are greenish molecules that contain something called a porphyrin ring, a stable ring-shaped molecule in which electrons can move freely. If they move freely the ring has the potential to gain or lose electrons, and then providing energized electrons to other molecules. This is the process in which chlorophyll captures light. Another type of pigment, Carotenoids, are red, yellow, or orange colored pigments. They include the compound carotene, which is where carrots get their color. Carotenoids pass their absorbed energy to chlorophyll because they cannot directly transfer sunlight energy into the photosynthetic pathway; and they are called accessory pigments for this reason. They also play a big role in getting rid of excess light, because a big amount of sunlight often kills pigments and other photosynthetic machinery, making the plants bleach.
The other class of pigments are called phycobilins. They are water soluble, and therefore are found in cytoplasm, however, these pigments are only found in algae and cyanobacteria. When a photon of just the right amount of energy hits a pigment, the pigment will absorb it and becomes excited, meaning it is no longer in its ground state, and an electron will jump to a higher energy orbital that lies further away from the nucleus. Most of the time an excited pigment transfers its extra energy to a neighboring molecule.
Through a process called the calvin cycle, plants create glucose out of sunlight. The Calvin cycle takes place in the stroma of chloroplasts because carbon dioxide enters the interior of a plant’s leaf through through pores called stomata which then diffuse the carbon dioxide into the stroma. The calvin cycle is where sugar is synthesized, and the reaction is also called the light-independent reaction because it is not directly driven by sunlight. In the process, carbon atoms from carbon dioxide are incorporated into organic molecules and used to make three-carbon sugars, also called G3P (glyceraldehyde-3-phosphate).
This process is dependent on, and fueled by ATP(adenosine triphosphate) and NADPH(nicotinamide adenine dinucleotide phosphate hydrogen) from the light dependant reactions. Basil is a plant that has had many culinary uses for thousands of years. Greek mythology explains what the origin of basil’s scientific name means. Ocimum basilicum is the botanical name, ocimus organized combats for Pallas, eventually he was killed by a gladiator and it is said that basil appeared when he died. The second half, basilium is a word derieved from the latin form of the greek word for king, or kingly. Basil is believed to have origins in india, and in india it was considered a sacred and powerful plant, often placed around temples and laid with the dead. Basil may also have been used as an embalming and preserving herb in ancient egypt because it has been found in many tombs.
In other countries, such as Crete and ancient greece and rome, basil was often associated with poverty and was considered an emblem of the devil. Some physicians in the 1500s thought that basil was poisonous, and that by simply smelling it, scorpions would grow in your brain. Basil is related to several culinary herbs such as rosemary, sage, and even lavender, because basil is a part of the large mint, or lamiaceae family. Another common kind of basil is ocimum basilicum purpurascens, or purple basil. Many growers have experienced purple basil turning green, and did not know the cause of it. Sometimes the plant is too dry and there are light and chemical problems. Purple basil needs at least 6 full hours of sunlight, and many times they are lacking nitrogen, also purple basil doesn’t grow very well in poor climates.
The hybrid parentage can often cause genetic instability when grown from seed, so leaf colour often varies from plant to plant. The purple colour is produced by retinal( the precursor of chlorophyll), Chlorophyll is often way more effective at harvesting sunlight so the plants often replace retinal with chlorophyll. In certain situations, it is better to grow purple basil indoors because you can control the climate, but sometimes grow lights aren’t always efficient because they can produce too much heat, which will kill the seedling, so in this situation, it is better to grow it outside