Phototroph

Photoautotrophs or Phototroph (Gk: φωτο = light, αὐτό. = self, τροϕή = nourishment) are organisms (usually plants) that carry out photosynthesis to acquire energy. Energy from sunlight is used to convert carbon dioxide and water into organic materials to be used in cellular functions such as biosynthesis and respiration. In an ecological context, they provide nutrition for all other forms of life (besides other autotrophs such as chemotrophs). In terrestrial environments plants are the predominant variety, while aquatic environments include a range of phototrophic organisms such as algae (e.g. kelp), other protists (such as euglena) and bacteria (such as cyanobacteria). One product of this process is starch, which is a storage or reserve form of carbon, which can be used when light conditions are too poor to satisfy the immediate needs of the organism. Photosynthetic bacteria have a substance called bacteriochlorophyll, live in lakes and pools, and use the hydrogen from hydrogen sulfide instead of from water, for the chemical process. (The bacteriochlorophyll pigment absorbs light in the extreme UV and infra-red parts of the spectrum which is outside the range used by normal chlorophyll). Cyanobacteria live in fresh water, seas, soil and lichen, and use a plant-like photosynthesis.

A photolithotrophic autotroph is an autotrophic organism that uses light energy, and an inorganic electron source (eg. H₂O, H₂, H₂S), and CO₂ as its carbon source. Examples include plants.

Cyanobacteria

Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria (Greek: κυανός (kyanós) = blue). They are a significant component of the marine nitrogen cycle and an important primary producer in many areas of the ocean, but are also found in habitats other than the marine environment; in particular cyanobacteria are known to occur in both freshwater, hypersaline inland lakes and in arid areas where they are a major component of biological soil crusts.

Bacteria

The bacteria ( [bækˈtɪərɪə] (help·info); singular: bacterium) are a large group of unicellular, prokaryote, microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×10³⁰) bacteria on Earth, forming much of the world's biomass. Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.

Algae

Algae (pronounced /ˈældʒiː/ or /ˈælɡiː/; singular alga /ˈælɡə/, Latin for "seaweed") are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in land plants.

Though the prokaryotic Cyanobacteria (commonly referred to as blue-green algae) were traditionally included as "algae" in older textbooks, many modern sources regard this as outdated as they are now considered to be closely related to bacteria. The term algae is now restricted to eukaryotic organisms. All true algae therefore have a nucleus enclosed within a membrane and chloroplasts bound in one or more membranes. Algae constitute a paraphyletic and polyphyletic group, as they do not include all the descendants of the last universal ancestor nor do they all descend from a common algal ancestor, although their chloroplasts seem to have a single origin. Diatoms are also examples of algae.

Plant

Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 18,000 bryophytes (see table below). Green plants, sometimes called Viridiplantae, obtain most of their energy from sunlight via a process called photosynthesis.

Sugar

Sugar is an informal term for a class of edible crystalline substances, mainly sucrose, lactose, and fructose characterized by a sweet flavor. In food, sugar almost exclusively refers to sucrose, which primarily comes from sugar cane and sugar beet. Other sugars are used in industrial food preparation, but are usually known by more specific names—glucose, fructose or fruit sugar, high fructose corn syrup, etc.

Excessive consumption of sucrose has been associated with increased incidences of type 2 diabetes, obesity and tooth decay.

Sugar consumption varies from country to country; Brazil has the highest per capita production and India the highest per-country consumption.

Organic compound

An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of compounds such as carbonates, simple oxides of carbon and cyanides, as well as the allotropes of carbon, are considered inorganic. The distinction between "organic" and "inorganic" carbon compounds while "useful in organizing the vast subject of chemistry... is somewhat arbitrary".

Organic chemistry is the science concerned with all aspects of organic compounds. Organic synthesis is the methodology of their preparation.

Carbon dioxide

Carbon dioxide (chemical formula CO₂) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state. CO₂ is a trace gas being only 0.038% of the atmosphere.

Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Small amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.