Paul Andersen explains how biology is ordered in the hierarchy of life. He first of all describes how emergent properties appear as you move to more inclusive systems. The then describes life at the following levels; atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, organisms, population, community, ecosystem, biome and finally biosphere. Show
De Agostini Picture Library / Getty Images Taxonomy is the practice of categorizing and naming of species. The official "scientific name" of an organism consists of its Genus and its Species Identifier in a naming system called binomial nomenclature. The Work of Carolus LinnaeusThe current taxonomic system gets its roots from the work of Carolus Linnaeus in the early 1700s. Before Linnaeus set up the rules of the two-word naming system, species had long and unwieldy Latin polynomials that were inconsistent and inconvenient for scientists when communicating with each other or even the public. While Linnaeus's original system had many fewer levels than the modern system has today, it was still an excellent place to start to organize all of life into similar categories for easier classification. He used the structure and function of body parts, mostly, to classify the organisms. Thanks to advances in technology and understanding the evolutionary relationships among species, we have been able to update the practice to get the most accurate classification system possible. The Taxonomic Classification SystemThe modern taxonomic classification system has eight main levels (from most inclusive to most exclusive): Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species Identifier. Every different species has a unique species identifier and the more closely a species is related to it on the evolutionary tree of life, it will be included in a more inclusive group with the species being classified. (Note: An easier way to remember the order of these levels is to use a mnemonic device to remember the first letter of each word in order. The one we use is "Do Keep Pond Clean Or Fish Get Sick") DomainA domain is the most inclusive of the levels (meaning it has the most number of individuals in the group). Domains are used to distinguish between the cell types and, in the case of prokaryotes, where they are found and what the cell walls are made of. The current system recognizes three domains: Bacteria, Archaea, and Eukarya. KingdomDomains are further broken into Kingdoms. The current system recognizes six Kingdoms: Eubacteria, Archaebacteria, Plantae, Animalia, Fungi, and Protista. PhylumThe next division would be the phylum. ClassSeveral related classes make up a phylum. OrderClasses are further divided into Orders. FamilyThe next level of classification that orders are divided into are Families. GenusA genus is a group of closely related species. The genus name is the first part of the scientific name of an organism. Species IdentifierEach species has a unique identifier that describes only that species. It is the second word in the two-word naming system of the scientific name of a species. Learning Outcomes
Living things are highly organized and structured, following a hierarchy that can be examined on a scale from small to large. The atom is the smallest and most fundamental unit of matter. It consists of a nucleus surrounded by electrons. Atoms form molecules. A molecule is a chemical structure consisting of at least two atoms held together by one or more chemical bonds. Many molecules that are biologically important are macromolecules, large molecules that are typically formed by polymerization (a polymer is a large molecule that is made by combining smaller units called monomers, which are simpler than macromolecules). An example of a macromolecule is deoxyribonucleic acid (DNA) (Figure 1), which contains the instructions for the structure and functioning of all living organisms.  Figure 1. All molecules, including this DNA molecule, are composed of atoms. (credit: “brian0918″/Wikimedia Commons) Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are small structures that exist within cells. Examples of organelles include mitochondria and chloroplasts, which carry out indispensable functions: mitochondria produce energy to power the cell, while chloroplasts enable green plants to utilize the energy in sunlight to make sugars. All living things are made of cells; the cell itself is the smallest fundamental unit of structure and function in living organisms. (This requirement is why viruses are not considered living: they are not made of cells. To make new viruses, they have to invade and hijack the reproductive mechanism of a living cell; only then can they obtain the materials they need to reproduce.) Some organisms consist of a single cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled or colonial organisms that do not have membrane-bound nuclei or organelles; in contrast, the cells of eukaryotes do have membrane-bound organelles and a membrane-bound nucleus. In larger organisms, cells combine to make tissues, which are groups of similar cells carrying out similar or related functions. Organs are collections of tissues grouped together performing a common function. Organs are present not only in animals but also in plants. An organ system is a higher level of organization that consists of functionally related organs. Mammals have many organ systems. For instance, the circulatory system transports blood through the body and to and from the lungs; it includes organs such as the heart and blood vessels. Organisms are individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled eukaryotes are also considered organisms and are typically referred to as microorganisms. All the individuals of a species living within a specific area are collectively called a population. For example, a forest may include many pine trees. All of these pine trees represent the population of pine trees in this forest. Different populations may live in the same specific area. For example, the forest with the pine trees includes populations of flowering plants and also insects and microbial populations. A community is the sum of populations inhabiting a particular area. For instance, all of the trees, flowers, insects, and other populations in a forest form the forest’s community. Keep in mind that the community level only consists of living organisms. The forest itself is an ecosystem; this is the first level that contains non-living aspects of a given area that impact the living things in that environment. An ecosystem consists of all the living things in a particular area together with the abiotic, non-living parts of that environment such as nitrogen in the soil or rain water. At the highest level of organization (Figure 2), the biosphere is the collection of all ecosystems, and it represents the zones of life on earth. It includes land, water, and even the atmosphere to a certain extent. Practice QuestionFrom a single organelle to the entire biosphere, living organisms are parts of a highly structured hierarchy. Figure 2. The biological levels of organization of living things are shown. From a single organelle to the entire biosphere, living organisms are parts of a highly structured hierarchy. (credit “organelles”: modification of work by Umberto Salvagnin; credit “cells”: modification of work by Bruce Wetzel, Harry Schaefer/ National Cancer Institute; credit “tissues”: modification of work by Kilbad; Fama Clamosa; Mikael Häggström; credit “organs”: modification of work by Mariana Ruiz Villareal; credit “organisms”: modification of work by “Crystal”/Flickr; credit “ecosystems”: modification of work by US Fish and Wildlife Service Headquarters; credit “biosphere”: modification of work by NASA) Which of the following statements is false?
Try ItTry ItContribute!Did you have an idea for improving this content? We’d love your input. Improve this pageLearn More What is the correct order from least inclusive to most inclusive?Answer and Explanation: From least inclusive to most inclusive: Species, Genus, Family, Order.
What is the hierarchy of life from smallest to largest?The levels, from smallest to largest, are: molecule, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere.
What is the correct ordering in the hierarchical levels of the organization of life from the least inclusive to the most inclusive or smallest to largest?Answer and Explanation: The correct sequence of arrangement of the levels of ecological organization from least to most inclusive is organism, population, community, ecosystem. Explanation: Organism is the lowest level of ecological organization which only includes the organism such as a plant or an animal.
What is the correct order for the hierarchy structure of life?The then describes life at the following levels; atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, organisms, population, community, ecosystem, biome and finally biosphere.
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What is the correct ordering in the hierarchy of organization of life from the least inclusive smallest to the most inclusive largest )?
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