Prokaryotes are distinguished from eukaryotes on the basis of nuclear organization, specifically their lack of a nuclear membrane. Prokaryotes also lack most of the intracellular organelles and structures that are characteristic of eukaryotic cells (an important exception is the ribosomes, which are present in both prokaryotic and eukaryotic cells). Most functions of organelles, such as mitochondria, chloroplasts, and the Golgi apparatus, are taken over by the prokaryotic plasma membrane. Prokaryotic cells have three architectural regions: appendages called flagella and pili - proteins attached to the cell surface; a cell envelope consisting of a capsule, a cell wall, and a plasma membrane; and a cytoplasmic region that contains the cell genome (DNA) and ribosomes and various sorts of inclusions.

Typical Prokaryotic Organisms are Bacteria and Archaea

There are 24 distinct human chromosomes: 22 autosomal chromosomes, plus the sex-determining X and Y chromosomes. Chromosomes 1–22 are numbered roughly in order of decreasing size. Somatic cells usually have one copy of chromosomes 1–22 from each parent, plus an X chromosome from the mother, and either an X or Y chromosome from the father, for a total of 46.

Chlorine, is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17. As the chloride ion, which is part of common salt and other compounds, it is abundant in nature and necessary to most forms of life, including humans. In its elemental form under standard conditions, it is a pale green gas about 2.5 times as dense as air. It has a disagreeable, suffocating odor that is detectable in concentrations as low as 3.5 ppm[1] and is poisonous. Chlorine is a powerful oxidant and is used in bleaching and disinfectants. It is also used in swimming pools to keep them clean. In the upper atmosphere, chlorine has been implicated in destruction of the ozone layer.

Sodium, atomic number 11, atomic mass 22.9898 g/mol, oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" (formerly known as ‘group IA’). It has only one stable isotope, 23Na. Sodium was first isolated by Sir Humphry Davy in 1807 by passing an electric current through molten sodium hydroxide. Sodium quickly oxidizes in air so it must be stored in an inert environment such as kerosene. Sodium is present in great quantities in the earth's oceans as sodium chloride. It is also a component of many minerals, and it is an essential element for animal life.

Violet, referring to the color of light at the short-wavelength end of the visible spectrum, approximately 380–420 nanometers when indigo is recognized, or more commonly 380–450 nm[1] (this is a spectral color).

The annelids, collectively called Annelida (from Latin anellus "little ring"), are a large phylum of animals, comprising the segmented worms, with about 15,000 modern species including the well-known earthworms and leeches. They are found in most wet environments, and include many terrestrial, freshwater, and especially marine species (such as the polychaetes), as well as some which are parasitic or mutualistic. They range in length from under a millimeter to over 3 metres (the seep tube worm Lamellibrachia luymesi).

In geology, a hotspot is a location on the Earth's surface that has experienced active volcanism for a long period of time. J. Tuzo Wilson came up with the idea in 1963 that volcanic chains like the Hawaiian Islands result from the slow movement of a tectonic plate across a "fixed" hot spot deep beneath the surface of the planet. Hotspots are thought to be caused by a narrow stream of hot mantle convecting up from the mantle-core boundary called a mantle plume, although some geologists prefer upper-mantle convection as a cause. This in turn has re-raised the antipodal pair impact hypothesis, the idea that pairs of opposite hot spots may result from the impact of a large meteor. Geologists have identified some 40-50 such hotspots around the globe, with Hawaii, Réunion, Yellowstone, Galápagos, and Iceland overlying the most currently active.

Most hotspot volcanoes are basaltic because they erupt through oceanic lithosphere (e.g., Hawaii, Tahiti). As a result, they are less explosive than subduction zone volcanoes, which have high water contents. Where hotspots occur under continental crust, basaltic magma is trapped in the less dense continental crust, which is heated and melts to form rhyolites. These rhyolites can be quite hot and form violent eruptions, despite their low water content. For example, the Yellowstone Caldera was formed by some of the most powerful volcanic explosions in geologic history.

Chaparral is a shrubland plant community found primarily in California, USA, that is shaped by a Mediterranean climate (mild, wet winters and hot dry summers) and wildfire. Similar plant communities are found in the five other Mediterranean climate regions around the world, including the Mediterranean Basin (where it is known as maquis), central Chile (matorral), South African Cape Region (known there as fynbos), and Australia (Western and Southern).

The word chaparral is a loan word from Spanish. The Spanish word comes from the word chaparro, which means both small and dwarf evergreen oak, which itself comes from the Basque word txapar, with the same meaning. A typical chaparral plant community consists of densely-growing evergreen scrub oaks and other drought-resistant shrubs. It often grows so densely that it is all but impenetrable to large animals and humans. This, and its generally arid condition, makes it notoriously prone to wildfires. Although many chaparral plant species require some fire cue (heat, smoke, or charred wood) for germination, chaparral plants are not "adapted" to fire per se. Rather, these species are adapted to particular fire regimes involving season, frequency, intensity and severity of the burn.

Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide to produce sugars. Chloroplasts capture light energy from the sun to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis. It is derived from the Greek words chloros which means green and plast which means form or entity. Chloroplasts are members of a class of organelles known as plastids.

Trace fossils, also called ichnofossils are structures preserved in sedimentary rocks that record biological activity. While we are most familiar with relatively spectacular, fossilized hard-part remains such as shells and bones (known as body fossils), trace fossils are often less dramatic, but nonetheless very important.

Strictly defined, trace fossils must reflect both the anatomy of their maker in some way, and be the result of behaviour. Sedimentary structures made by empty shells rolling along the sea floor are thus excluded (as "death marks"), as are structures such as stromatolites that, although the result of behaviour, do not reflect the anatomy of their maker. Spun coccoons and spiders webs are considered to be trace fossils, as they are manipulated by their makers after secretion; egg cases, on the other hand, are not.

Trace fossils include burrows (such as Chondrites), borings, ichnites (footprints and track marks), Zoophycus feeding marks, trails (such as Cruziana scratched by trilobites), coprolites (fossilized droppings) and other gut-derived objects, and rhizoliths or rhizocretions (the fossil remains of roots).

The study of trace remains is called ichnology, which is divided into paleoichnology, or the study of trace fossils, and neoichnology, the study of modern trace remains.

The science of ichnology is quite challenging, as most trace remains cannot be positively assigned to a specific organism or even to a specific class of organisms. Furthermore, trace remains such as burrows can make the work for paleontologists and paleobiologists more difficult as they rework sediments, causing older strata to be mixed with younger ones. This can cause some confusion in interpretation, unless viewed in geologic context.

Adolf Seilacher divided trace fossils into five main behavioral groups:

1. Domichnia are dwelling structures that reflect the life position of the organism that created it;
2. Fodinichnia are three-dimensional structures left by animals which eat their way through sediment, such as deposit feeders;
3. Pascichnia are another type of feeding trace, left by grazers on the surface of a soft sediment or a mineral substrate;
4. Cubichnia are resting traces, in the form of an impression left by an organism on a soft sediment;
5. Repichnia are surface traces of creeping and crawling, as an organism moved from one station to another.

Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. They are united by having, at some time in their life, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a muscular tail extending past the anus. Some scientists argue that the true qualifier should be pharyngeal pouches rather than slits.[citation needed]

The phylum Chordata is broken down into three subphyla: Urochordata, Cephalochordata, and Vertebrata. Urochordate larvae have a notochord and a nerve cord but they are lost in adulthood. Cephalochordates have a notochord and a nerve cord but no vertebrae. In all vertebrates except for Hagfish, the dorsal hollow nerve cord has been surrounded with cartilaginous or bony vertebrae and the notochord generally reduced.

The chordates and two sister phyla, the hemichordates and the echinoderms, make up the deuterostomes, a superphylum.

The extant groups of chordates are related as shown in the phylogenetic tree below. Many of the taxa listed do not match traditional classes because several of those classes are paraphyletic. Different attempts to organize the profusion of chordate clades into a small number of groups, some with and some without paraphyletic taxa, have thrown vertebrate classification into a state of flux. Also, the relationships of some chordate groups are not very well understood.

Chordates all have:

1. a notochord at least at one point in their life
2. a tail that extends farther than their anus
3. a backbone

The chordata phylum contains vertebrates and invertebrates. Some familar animals, such as cats, dogs, hamsters, monkeys, and humans themselves are in the Chordata phylum.

An autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces complex organic compounds from simple molecules and an external source of energy, such as light or chemical reactions of inorganic compounds. Autotrophs are considered producers in a food chain. Plants and other organisms that carry out photosynthesis are phototrophs (or photoautotrophs). Bacteria that utilize the oxidation of inorganic compounds such as hydrogen sulfide, ammonium or ferrous iron as an energy source are chemoautotrophs (some are known as lithotrophs).

Autotrophs are a vital part of the food chains of all ecosystems. They take energy from the environment (sun light or inorganic sources) and use it to process carbon-based and other organic molecules that are used to carry out various biological functions such as cell growth. Other organisms, called heterotrophs, utilize autotrophs as food to carry out these same functions. Thus, heterotrophs — animals, fungi, as well as most bacteria and protozoa — depend on autotrophs for both energy and raw materials to make complex organic molecules. This mechanism is called primary production in the sea. Heterotrophs obtain energy by breaking down organic molecules obtained in food. Carnivorous animals ultimately rely on autotrophs because the energy and organic building blocks obtained from their prey comes from autotrophs they preyed upon.

There are some species of organisms that require organic compounds as a source of carbon, but are able to use light or inorganic compounds as a source of energy. Such organisms are not defined as autotrophic, but rather as heterotrophic. An organism that obtains carbon from organic compounds but obtains energy from light is called a photoheterotroph, while an organism that obtains carbon from organic compounds but obtains energy from the oxidation of inorganic compounds is termed a chemoheterotroph.