A report on BiologyOrganism and Evolution

Diagram of a fly from Robert Hooke's innovative Micrographia, 1665
The bacterium Escherichia coli (E. coli), is a single-celled prokaryote
Lucretius
In 1842, Charles Darwin penned his first sketch of On the Origin of Species.
An amoeba is a single-celled eukaryote
Alfred Russel Wallace
In the Bohr model of an atom, electrons (blue dot) orbit around an atomic nucleus (red-filled circle) in specific atomic orbitals (grey empty circles).
Polypore fungi and angiosperm trees are large multicellular eukaryotes.
Thomas Robert Malthus
Model of hydrogen bonds (1) between molecules of water
Precambrian stromatolites in the Siyeh Formation, Glacier National Park. In 2002, a paper in the scientific journal Nature suggested that these 3.5 Gya (billion years old) geological formations contain fossilized cyanobacteria microbes. This suggests they are evidence of one of the earliest known life forms on Earth.
In 1842, Charles Darwin penned his first sketch of On the Origin of Species.
Organic compounds such as glucose are vital to organisms.
LUCA may have used the Wood–Ljungdahl or reductive acetyl–CoA pathway to fix carbon.
DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix.
A phospholipid bilayer consists of two adjacent sheets of phospholipids, with the hydrophilic tails facing inwards and the hydrophobic heads facing outwards.
Duplication of part of a chromosome
The (a) primary, (b) secondary, (c) tertiary, and (d) quaternary structures of a hemoglobin protein
This diagram illustrates the twofold cost of sex. If each individual were to contribute to the same number of offspring (two), (a) the sexual population remains the same size each generation, where the (b) Asexual reproduction population doubles in size each generation.
Structure of an animal cell depicting various organelles
Mutation followed by natural selection results in a population with darker colouration.
Structure of a plant cell
Simulation of genetic drift of 20 unlinked alleles in populations of 10 (top) and 100 (bottom). Drift to fixation is more rapid in the smaller population.
Example of an enzyme-catalysed exothermic reaction
Homologous bones in the limbs of tetrapods. The bones of these animals have the same basic structure, but have been adapted for specific uses.
Respiration in a eukaryotic cell
A baleen whale skeleton. Letters a and b label flipper bones, which were adapted from front leg bones, while c indicates vestigial leg bones, both suggesting an adaptation from land to sea.
Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar.
Common garter snake (Thamnophis sirtalis sirtalis) has evolved resistance to the defensive substance tetrodotoxin in its amphibian prey.
In meiosis, the chromosomes duplicate and the homologous chromosomes exchange genetic information during meiosis I. The daughter cells divide again in meiosis II to form haploid gametes.
The four geographic modes of speciation
Punnett square depicting a cross between two pea plants heterozygous for purple (B) and white (b) blossoms
Geographical isolation of finches on the Galápagos Islands produced over a dozen new species.
Bases lie between two spiraling DNA strands.
Tyrannosaurus rex. Non-avian dinosaurs died out in the Cretaceous–Paleogene extinction event at the end of the Cretaceous period.
The extended central dogma of molecular biology includes all the processes involved in the flow of genetic information.
The hominoids are descendants of a common ancestor.
Regulation of various stages of gene expression
As evolution became widely accepted in the 1870s, caricatures of Charles Darwin with an ape or monkey body symbolised evolution.
Composition of the human genome
Construction of recombinant DNA, in which a foreign DNA fragment is inserted into a plasmid vector
Model of concentration gradient building up; fine yellow-orange outlines are cell boundaries.
Natural selection for darker traits
Comparison of allopatric, peripatric, parapatric and sympatric speciation
Bacteria – Gemmatimonas aurantiaca (-=1 Micrometer)
Archaea – Halobacteria
Diversity of protists
Diversity of plants
Diversity of fungi. Clockwise from top left: Amanita muscaria, a basidiomycete; Sarcoscypha coccinea, an ascomycete; bread covered in mold; chytrid; Aspergillus conidiophore.
Bacteriophages attached to a bacterial cell wall
Root and shoot systems in a eudicot
The xylem (blue) transports water and minerals from the roots upwards whereas the phloem (orange) transports carbohydrates between organs.
Reproduction and development in sporophytes
Negative feedback is necessary for maintaining homeostasis such as keeping body temperature constant.
Diffusion of water and ions in and out of a freshwater fish
Different digestive systems in marine fishes
Respiratory system in a bird
Circulatory systems in arthropods, fish, reptiles, and birds/mammals
Asynchronous muscles power flight in most insects. a: Wings b: Wing joint c: Dorsoventral muscles power upstrokes d: Dorsolongitudinal muscles power downstrokes.
Mouse pyramidal neurons (green) and GABAergic neurons (red)
Sexual reproduction in dragonflies
Cleavage in zebrafish embryo
Processes in the primary immune response
Brood parasites, such as the cuckoo, provide a supernormal stimulus to the parenting species.
Terrestrial biomes are shaped by temperature and precipitation.
Reaching carrying capacity through a logistic growth curve
A (a) trophic pyramid and a (b) simplified food web. The trophic pyramid represents the biomass at each level.
Fast carbon cycle showing the movement of carbon between land, atmosphere, and oceans in billions of tons per year. Yellow numbers are natural fluxes, red are human contributions, white are stored carbon. Effects of the slow carbon cycle, such as volcanic and tectonic activity, are not included.
Efforts are made to preserve the natural characteristics of Hopetoun Falls, Australia, without affecting visitors' access.

In biology, an organism is any organic, living system that functions as an individual entity.

- Organism

For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations.

- Biology

Another major theme is evolution, which explains the unity and diversity of life.

- Biology

It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms and molecules.

- Evolution

Their discoveries have influenced not just the development of biology but numerous other scientific and industrial fields, including agriculture, medicine, and computer science.

- Evolution

While viruses sustain no independent metabolism and thus are usually not classified as organisms, they do have their own genes, and they do evolve by mechanisms similar to the evolutionary mechanisms of organisms.

- Organism
Diagram of a fly from Robert Hooke's innovative Micrographia, 1665

5 related topics with Alpha

Overall

All adult Eurasian blue tits share the same coloration, unmistakably identifying the morphospecies.

Species

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All adult Eurasian blue tits share the same coloration, unmistakably identifying the morphospecies.
A region of the gene for the cytochrome c oxidase enzyme is used to distinguish species in the Barcode of Life Data Systems database.
The cladistic or phylogenetic species concept is that a species is the smallest lineage which is distinguished by a unique set of either genetic or morphological traits. No claim is made about reproductive isolation, making the concept useful also in palaeontology where only fossil evidence is available.
A chronospecies is defined in a single lineage (solid line) whose morphology changes with time. At some point, palaeontologists judge that enough change has occurred that two species (A and B), separated in time and anatomy, once existed.
A cougar, mountain lion, panther, or puma, among other common names: its scientific name is Puma concolor.
The type specimen (holotype) of Lacerta plica, described by Linnaeus in 1758
Ernst Mayr proposed the widely used Biological Species Concept of reproductive isolation in 1942.
Palaeontologists are limited to morphological evidence when deciding whether fossil life-forms like these Inoceramus bivalves formed a separate species.
Horizontal gene transfers between widely separated species complicate the phylogeny of bacteria.
John Ray believed that species breed true and do not change, even though variations exist.
Carl Linnaeus created the binomial system for naming species.
Blackberries belong to any of hundreds of microspecies of the Rubus fruticosus species aggregate.
The butterfly genus Heliconius contains many similar species.
The Hypsiboas calcaratus–fasciatus species complex contains at least six species of treefrog.
Carrion crow
Hybrid with dark belly, dark gray nape
Hybrid with dark belly
Hooded crow
Seven "species" of Larus gulls interbreed in a ring around the Arctic.
Opposite ends of the ring: a herring gull (Larus argentatus) (front) and a lesser black-backed gull (Larus fuscus) in Norway
A greenish warbler, Phylloscopus trochiloides
Presumed evolution of five "species" of greenish warblers around the Himalayas

In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.

If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change.

Life

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Quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy transformation, and reproduction.

Quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy transformation, and reproduction.

Adenovirus as seen under an electron microscope
Definition of cellular life according to Budisa, Kubyshkin and Schmidt.
The structure of the souls of plants, animals, and humans, according to Aristotle
Cyanobacteria dramatically changed the composition of life forms on Earth by leading to the near-extinction of oxygen-intolerant organisms.
Deinococcus radiodurans is an extremophile that can resist extremes of cold, dehydration, vacuum, acid, and radiation exposure.
Animal corpses, like this African buffalo, are recycled by the ecosystem, providing energy and nutrients for living creatures

Biology is the science that studies life.

Organisms, or the individual entities of life, are generally thought to be open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve over multiple generations.

The Tasmanian tiger (Thylacinus cynocephalus) is an example of an extinct species.

Extinction

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The Tasmanian tiger (Thylacinus cynocephalus) is an example of an extinct species.
External mold of the extinct Lepidodendron from the Upper Carboniferous of Ohio
Skeleton of various extinct dinosaurs; some other dinosaur lineages still flourish in the form of birds
The dodo of Mauritius, shown here in a 1626 illustration by Roelant Savery, is an often-cited example of modern extinction.
The passenger pigeon, one of the hundreds of species of extinct birds, was hunted to extinction over the course of a few decades.
Scorched land resulting from slash-and-burn agriculture
The golden toad was last seen on May 15, 1989. Decline in amphibian populations is ongoing worldwide.
The large Haast's eagle and moa from New Zealand
Tyrannosaurus, one of the many extinct dinosaur genera. The cause of the Cretaceous–Paleogene extinction event is a subject of much debate amongst researchers.
Georges Cuvier compared fossil mammoth jaws to those of living elephants, concluding that they were distinct from any known living species.
A great hammerhead caught by a sport fisherman. Human exploitation now threatens the survival of this species. Overfishing is the primary driver of shark population declines, which have fallen over 71% since 1970.

Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species.

Through evolution, species arise through the process of speciation—where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche—and species become extinct when they are no longer able to survive in changing conditions or against superior competition.

Extinction is an important research topic in the field of zoology, and biology in general, and has also become an area of concern outside the scientific community.

The structure of the DNA double helix. The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.

DNA

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The structure of the DNA double helix. The atoms in the structure are colour-coded by element and the detailed structures of two base pairs are shown in the bottom right.
Chemical structure of DNA; hydrogen bonds shown as dotted lines. Each end of the double helix has an exposed 5' phosphate on one strand and an exposed 3' hydroxyl group (—OH) on the other.
A section of DNA. The bases lie horizontally between the two spiraling strands ([[:File:DNA orbit animated.gif|animated version]]).
DNA major and minor grooves. The latter is a binding site for the Hoechst stain dye 33258.
From left to right, the structures of A, B and Z DNA
DNA quadruplex formed by telomere repeats. The looped conformation of the DNA backbone is very different from the typical DNA helix. The green spheres in the center represent potassium ions.
A covalent adduct between a metabolically activated form of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA
Location of eukaryote nuclear DNA within the chromosomes
T7 RNA polymerase (blue) producing an mRNA (green) from a DNA template (orange)
DNA replication: The double helix is unwound by a helicase and topo­iso­merase. Next, one DNA polymerase produces the leading strand copy. Another DNA polymerase binds to the lagging strand. This enzyme makes discontinuous segments (called Okazaki fragments) before DNA ligase joins them together.
Interaction of DNA (in orange) with histones (in blue). These proteins' basic amino acids bind to the acidic phosphate groups on DNA.
The lambda repressor helix-turn-helix transcription factor bound to its DNA target
The restriction enzyme EcoRV (green) in a complex with its substrate DNA
Recombination involves the breaking and rejoining of two chromosomes (M and F) to produce two rearranged chromosomes (C1 and C2).
The DNA structure at left (schematic shown) will self-assemble into the structure visualized by atomic force microscopy at right. DNA nanotechnology is the field that seeks to design nanoscale structures using the molecular recognition properties of DNA molecules.
Maclyn McCarty (left) shakes hands with Francis Crick and James Watson, co-originators of the double-helix model.
Pencil sketch of the DNA double helix by Francis Crick in 1953
A blue plaque outside The Eagle pub commemorating Crick and Watson
Impure DNA extracted from an orange

Deoxyribonucleic acid (DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.

This ancient RNA world where nucleic acid would have been used for both catalysis and genetics may have influenced the evolution of the current genetic code based on four nucleotide bases.

Modern biology and biochemistry make intensive use of these techniques in recombinant DNA technology.

Description of rare animals (写生珍禽图), by Song dynasty painter Huang Quan (903–965)

Taxonomy (biology)

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Description of rare animals (写生珍禽图), by Song dynasty painter Huang Quan (903–965)
Title page of Systema Naturae, Leiden, 1735
Evolution of the vertebrates at class level, width of spindles indicating number of families. Spindle diagrams are typical for evolutionary taxonomy
The same relationship, expressed as a cladogram typical for cladistics
The basic scheme of modern classification. Many other levels can be used; domain, the highest level within life, is both new and disputed.
Type specimen for Nepenthes smilesii, a tropical pitcher plant
A comparison of phylogenetic and phenetic (character-based) concepts

In biology, taxonomy is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics.

With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolutionary relationships among organisms, both living and extinct.